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山东大学医学院 解剖教研室 李振华 Content Part Ⅰ The Sensory Organs 2 The Visual Organ 2 The Vestibulocochlear Organ 9 Part Ⅱ The Central Nervous System 17 Introduction 17 The Spinal Cord 20 The brain stem 27 The Cerebellum 36 The Diencephalon 40 The Telencephalon 45 The Nervous pathway 51 The Meninges and Blood Vessels of Brain 60 Part Ⅲ The Peripheral Nervous System 69 The Spinal Nerves 69 The Cranial Nerves 77 The Visceral Nervous System 86 Part IV The Endocrine System 94 1 Part ⅠThe Sensory Organs Sensory organs include the receptors and accessory organs. The receptors may be divided into three kinds: ①The exteroceptors: receive stimuli such as touch, temperature, pain, light and sound from the external environment ②The interoceptors: pick up information about internal environment ③The proprioceptors: receive stimuli from muscles, tendons, joints and ligaments The Visual Organ Learning Objectives You should: Know the shape of eyeball Understand the feature, structure and function of the wall of eyeball Understand the position of the chamber of eye, production and circulation of aqueous humor Understand the position and feature of lens and vitreous body Know the formation and function of the accessory organs of eye (eyelids, sheath of eyeball, adipose body of orbit) Understand feature and divisions of the conjunctiva, the position of the lacrimal gland, the formation of the lacrimal apparatus and its opening, the names and functions of the extraocular muscles Know the origin and disbution of the arteries of eye, the branches of the central artery of retina and the veins of eye. Composition the visual organ: eyeball and accessory organs of eye Ⅰ. Shape of eyeball Consists of a sphere, approximately 2.5 cm in diameter Has anterior and posterior poles Equator: an imaginary line encircling the eyeball, midway between anterior and posterior poles Axis of eyeball: a line joining the two poles 2 Optic axis: a line joining the center of the pupil to the fovea centralis The lateral walls are at right angles to each other. Ⅱ. Wall of eyeball A. Fibrous tunic of eyeball (outer fibrous layer) 1. Cornea: anterior one-sixth, a nonvascular, transparent portion, richly supplied by nerves; because it is curved, the cornea helps focus light 2. Sclera (white of eye, opaque portion): posterior five-sixths consisting of fibrous connective tissue that forms a tough protective covering for eyeball, and containing sinus venosus sclerae which lies beneath the junction of cornea and sclera for drainage of aqueous humor to venous system B. Vascular tunic of eyeball (middle vascular layer): 1. Iris Thin contractile membrane anterior to ciliary body, with a central opening, the pupil Contains sphincter pupillae (circular fibers) and dilator pupillae (radial fibers) Partitions anterior and posterior chambers, containing aqueous humor Cornea and iris meet to form the iridocorneal angle Iris Ciliary body Ciliary zonule 2. Ciliary body Body a ring-shaped thickening anterior to equator, containing smooth muscle fibers called ciliary muscle Ciliary processes: a series of some 60~80 projections producing aqueous humor Attached by ciliary zonule to lens 3. Choroid Thin, highly vascular in posterior 2/3 of eye 3 Contains brown pigmented cells and dense capillary plexus C. Internal tunic of eyeball — retina 1. Pars caeca retinae: lines the ciliary body and iris, nonreceptive and consists merely of pigment cells 2. Pars optica retinae: lines the choroids, an extension of diencephalon, and extends forward to ora serrata ; composed of two layers: an outer pigment cell layer and an inner neural layer, the light-sensitive retina. The ueural layer consists of four layers of nerve and supporting cells through which light rays must pass to reach the photosensitive cells. The fourth layer consists photoreceptor cells ⑴Cone cells are color receptors that function best during the day ⑵Rod cells are dark-light receptors that function best at night and in dim light The third layer consists of bipolar neurons, equivalent to cells of dorsal root ganglia The second layer is formed ganglion cells, whose axons form the superficial layer of optic nerve fibers The first layer consists of nerve axons that collect at the optic disk and pass through the sclera to form the optic nerve Optic disc (blind spot), located medial to posterior pole of eye, and consists of optic nerve fibers and central artery of retina Macula lutea ⑴ Lies lateral about 3.5 mm to optic disc, a shallow depression, it is completely free of blood vessels and is yellowish in color ⑵ Fovea centralis, aera of greatest visual acuity (concentration of cones), at its center The pigmentted layer absorbs light that passes completely through the anterior layer, preventing backscatter (blurring of vision) Optic disc Macula lutea Ⅲ. Contents of eyeball 4 A. Aqueous humor 1. Chamber of eye lies between cornea and lens, and divided by iris into anterior and posterior chambers 2. Production and circulation of aqueous humor: aqueous humor is a clear watery fluid that fills chamber of eye Aqueous humor is continuously secreted by ciliary body into posterior chamber It passes through pupil into anterior chamber Then it filters though iridocorneal angle into sinus venosus sclerae, this sinus drains via anterior ciliary veins into ophthalmic veins Ciliary body posterior chamber pupil sinus venosus sclera anterior chamber iridocorneal angle anterior ciliary vein ophthalmic vein 3. Functions Helps focus light Helps maintain constant pressure in eyeball Helps nourish the lens and cornea B. Lens Transparent biconvex structure, covered by an elastic transparent capsule Located between iris and vitreous body, and suspended behind pupil by ciliary zonule Shape changed by the ciliary muscle: for near vision, the ciliary muscle contracts and the lens rounds up, while for distant vision the lens flattens out, so that the eye may be focused on distant objects C. Vitreous body Consists of colorless, transparent jelly-like substance in which there is a meshwork of fine fibrils, occupies the vitreous chamber, the space between lens and retina Helps maintain the shape of eyeball and supports the retina D. Refractive media: cornea, aqueous humor, lens, and vitreous body constitute the refractive media of eye which bend entering light waves and focus them on the retina Ⅳ. Accessory organs of eye A. Eyelids 5 1. Paired, upper and lower 2. Each consist of following layers, from without inwards: Skin, extremely thin Subcutaneous areola tissue, loose and delicate Muscular layer: orbicularis oculi Tarsus, formed by dense connective tissue in which the tarsal glands embedded Lined by palpebral conjunctiva 3. Function: to protect, open, and close eye B. Conjunctiva 1. Thin mucous membrane 2. Three parts Palpebral conjunctiva: lining inner surface of eyelids Bulbar conjunctiva: lining anterior part of sclera, up to corneal margin Conjuntival fornix (superior and inferior): line of reflection of bulbar and palpebral conjunctiva 3. Conjunctival sac C. Lacrimal apparatus 1. Lacrimal gland Oval 2-cm, occupies fossa for lacrimal gland Ducts (6~10 in number): empty into anterior region of superior fornix of conjunctiva Secrets tears, which move across eyeball to medial angle,protect and 2. Lacrimal passages: drains tears from eye to nose moisten eye Paired lacrimal puncta opening to lacrimal ductules, one on each eylid margin near medial angle Lacrimal ductules: one in each lid, pass medially, join and enter lacrimal sac Lacrimal sac within fossa for lacrimal sac, opening into nasolacrimal duct Nasolacrimal duct courses 2 cm inferiorly and opens into inferior nasal meatus 3. Tear is produced by lacrimal gland, passes through superior conjunctival fornix into 6 conjunctival sac, and then is drained through lacrimal punctum, lacrimal ductule, lacrimal sac and nasolacrimal duct into inferior nasal meatus. D. Ocular muscles There are seven ocular muscles, all of which move the eyeball except levator palpebrae superioris, which elevates upper eyelid. Medial rectus Superior rectus levator palpebrae superioris Lateral rectus Superior obliquus 1. Recti muscles (four) Named for their relationship to eyeball: ①superior, ②inferior, ③medial,④lateral Arise from common tendinous ring situated at the apex of orbit All inserting into sclera posterior to the corneal margin 2. Oblique muscles (two) Superior obliquus arises from common tendinous ring , and passes anteriorly, narrows to a tendon passing through a connective tissue pulley, and then courses posteriorly and downward, inserts into sclera behind equator Inferior obliquus arises from the floor of orbit, inserts into sclera behind equator Muscles of the eyeballs and eyelids Muscle Action Nerve supply levator palpebrae superioris Raises upper eyelid Ⅲ Superior rectus Turns eyeball superomedially Ⅲ Inferior rectus Turns eyeball inferomedially Ⅲ Medial rectus Turns eyeball medially Ⅲ Lateral rectus Turns eyeball laterally Ⅵ Superior obliquus Turns eyeball inferolaterally Ⅳ Inferior obliquus Turns eyeball superolaterally Ⅲ E. Connective tissue in the orbit 7 Sheath of eyeball: a thin membrane, which surrounds the eyeball from optic nerve to corneoscleral junction, permits the eyeball to move in the orbit without friction Adipose body of orbit: lies between sheath of eyeball and the orbit acts as a protective cushion and shock sorber for the eyeball F. Vessels of eye 1. Ophthalmic artery Branch of internal artery Branches-central artery of retina ⑴ Enters optic nerve, passes toward the optic disk and then fans out to supply the retina ⑵Four branches: superior and inferior nasal or temporal arteriole of retina 2. Ophthalmic vein Superior ophthalmic vein communicates with facial vein anteriorly, exits posteriorly via superior orbital fissure to drain into cavernous sinus Inferior ophthalmic vein lies on floor of orbit and communicates with pterygoid plexus, exits via superior orbital fissure to drain into cavernous sinus Sdudy questions Ⅰ. Single choice questions (there five choices on each question, only one is correct, please circle the correct answer): 1.The refractive media of eyeball does not include A. cornea B. aqueous humor C. lens D. retina E. vitreous body 2.iris A. is the largest part of middle tunic B. divides chamber of the eye into anterior and posterior chambers C. iris and sclera meet to form angle of anterior chamber 8 D. during near vision of light shone on retina the pupil dilates E. is colourless and transparant Ⅱ. Multiple choice questions (two to five choices are correct, please circle the correct answers): 1.The muscles turn the anterior pole of eyeball medially include A. superior rectus B. superior obliquue C. inferior rectus D. inferior obliquue E. medial rectus 2.Vascular tunic of eyeball includes A. Cornea B. Sclera C. Iris D. Ciliary body E. Choroid Ⅲ. Answer the following questions 1. Write out the name of ocular muscles and nerves innervated the muscles. 2. Describe the feature and structure of the wall of eyeball. 3. Write out the production and circulation of aqueous humor. The Vestibulocochlear Organ Learning Objectives You should: 9 了解前庭蜗器的分部和各部的机能。 了解外耳的组成。掌握外耳道的位置、形态、分部和婴儿外耳道的特点。 掌握鼓膜的形态、位置和分部。 掌握中耳的组成。掌握鼓室的位置、六个壁的主要形态结构及毗邻,并了解其临床意 义。了解听小骨的名称和排列。 掌握咽鼓管的位置、分部、开口部位和作用、幼儿咽鼓管的特点。 掌握乳突窦和乳突小房的位置。 掌握内耳的位置和分部、骨迷路的分部、各部的形态以及骨迷路与膜迷路的位置关系。 了解膜迷路各部的形态与功能。 掌握听觉和位置觉感受器的位置与机能。 了解声波的传导途径。 Ⅰ. General features A. Organ of hearing and balance B. Three parts 1. External ear: collects sound waves 2. Middle ear: transmits sound waves 3. Internal ear: contains the vestibulocochlear organ concerned with equilibration and hearing Ⅱ. External ear A. Auricle: a fibrocartilage skeleton, covered by skin 10 B. External acoustic meatus A slender canal that extends from external acoustic pore to tympanic membrane (about 2.5 cm length in an adult). The lateral third is cartilaginous and the medial two thirds are bony. It is lined by a layer of thin skin. Ceruminous and sebaceous glands produce cerumen (wax). This S-shaped passage medially, at first forward and upward, then backward and, finally forward and downward. C. Tympanic membrane 1. A thin oval membrane, about 1 cm in diameter, lying obliquely between external acoustic meatus and tympanic cavity, faces downwards, forwards and laterally, outer suface of skin, inner surface of mucous membrane, a concavity toward the meatus, with a central depression — umbo 2. Two parts a) Flaccid part: upper 1/4 b) Tense part: lower 3/4 ⑴Umbo of tympanic membrane ⑵Cone of light Ⅲ. Middle ear A. Tympanic cavity 1. An air-containing cavity locates within petrous portion of temporal bone 2. Walls a) Roof or tegmental wall formed by tegmen tympani, separates tympanic cavity from middle cranial fossa b) Floor or jugular wall separates the cavity from superior bulb of internal jugular vein 11 c) Anterior wall or carotid wall separates tympanic cavity from carotid canal, superiorly lies two openings: ⑴Upper opening for tensor tympani muscle ⑵Lower opening for auditory tube, which communicates with nasopharynx d) Posterior wall or mastoid wall ⑴Connected by aditus to mastoid antrum and air cells ⑵Pyramid, a bony projection for attachment of stapedius tendon e) lateral wall or membranous wall formed by tympanic membrane with epitympanic recess superiorly f) Medial wall or labyrinthine wall separates tympanic cavity from inner ear ⑴ Centrally, a rounded promontory formed by first turn of cochlea ⑵ Fenestra vestibuli covered by base of stapes ⑶ Fenestra cochleae covered by secondary tympanic membrane ⑷ Prominence of facial canal containing the facial nerve 3. Auditory ossicles a) Consists of chain of three bones: malleus, incus, and stapes. b) Articulate by synovial joints c) Transmit vibration of tympanic membrane to footplate of stapes in fenestra vestibule. d) Transmission of vibration modified by two small muscles ⑴Tensor tympani dampens vibration of the tympanic membrane ⑵ Stapedius dampens vibration of the stapes B. Auditory tube 1. About 3~4 cm long, extends from nasopharynx posteriorly, laterally, and upward to tympanic cavity 12 2. Two parts a) Bony part: posterolateral one-third formed by temporal bone extension of tympanic cavity b) Cartilaginous part: medial two-thirds composed of cartilage 3. Functions to equalize air pressure on either side of tympanic membrane 4. In childhood, it is shorter, wider and more horizontal than in adult C. Mastoid antrum and mastoid cells 1. Mastoid antrum: a small chamber between tympanic cavity and mastoid cells, the aditus to the antrum connects the mastoid antrum to the epitympanic recess of the tympanic cavity, the floor of antrum communicates with mastoid cells via several openings 2. Mastoid cells: contain a group of air cells within mastoid process of temporal bone Ⅳ. Internal ear A. General features 1. Lies within the petrous portion of temporal bone 2. Key contents of internal ear a) Bony labyrinth, a series of bony canal, contains perilymph that suspends the membranous labyrinth b) Membranous labyrinth, a system of continuous membranous canals, is filled with endolymph and contains the sensory organs B. Parts of bony labyrinth 1. Cochlea, anteriorly a) It somewhat resembles a snail’s shell b) Cochlear spiral canal makes two and one-half spinal turns around the modiolus c) A small shelf of bone, the osseous spiral lamina, protrudes from the modiolus, 13 like the thread on a screw d) Scala vestibuli ⑴ Upper canal of cochlear spinal canal, associated with vestibular wall of cochlear duct ⑵Contains perilymph, which transmits vibrations from fenestra vestibuli ⑶communicates at apex of cochlea (helicotrema) with scala tympani e) Scala tympani ⑴ Lower canal of cochlear spinal canal, associated with tympanic wall of cochlear duct ⑵Contain perilymph, which transmits spent vibrations to fenestra cochleae 2. Vestibule, centrally a) Hollow bony space b) Contains utricle and saccule 3. Bony semicircular canals (anterior, posterior, and lateral) posteriorly a) Semicircular duct in each b) Canal at right angles to each other 1) The anterior bony semicircular canal is vertically with the long axis of the petrous portion of temporal bone 2) The lateral bony semicircular canal is nearly horiaontal 3) The posterior bony semicircular canal is paralles to the long axis of the petrous portion of temporal bone c) Dilated ampulla in each canal C. Membranous labyrinth 1. Cochlear duct a) Enclosed by tympanic wall and vestibular wall b) Contains spinal organ (of Corti), the sound receptors lies on tympanic wall of cochlear duct, stimulated by the 14 movement of endolymph in the duct 2. Utricle and saccule a) Membranous sacs in vestibule b) Connected to each other, cochlear duct, and semicircular ducts c) Contain macular utricli and macular sacculi, end organs of balance, which respond to linear acceleration and deceleration, static of gravity 3. Semicircular ducts a) Contained in bony semicircular canals b) Contain endolymph c) Each duct has a membranous ampullae at one end containing crista ampullaris, receptors of balance that respond to rotational acceleration in three different planes Ⅴ. Conduction of sound A. Air-conduction of sound 1. Auricle collects sound waves 2. Sound waves enter the external auditory canal, strike the tympanic membrane, pass through the ossicles, strike the fenestra vestibuli, set up waves in the perilymph, strike the vestibular membrane and scala tympani that transmit vibration to the spinal organ 3. Hair cells in the spinal organ produce receptor potentials, which elicit nerve impulses in the cochlear branch of vestibulochochlear (Ⅷ) nerve B. Bony- conduction of sound Sound waves → skull → bony labyrinth → perilymph → endolymph within cochlear duct → spinal organ Ⅵ. Internal acoustic meatus A. Extends from internal acoustic pore to fundus of internal acoustic meatus B. Facial, vestibulocochlear nerves and vessles of labyrinth pass through the fundus of 15 internal acoustic meatus Sdudy questions Ⅰ. Single choice questions (there five choices on each question, only one is correct, please circle the correct answer): 1. Tympanic cavity can not communicate with outside The posterior wall is labyrinthine wall The anterior wall is jugular wall The inferior wall is mastoid wall The lateral wall is membranous wall 2. Spiral organ lies in tympanic cavity semicircular canals fenestra vestibuli basilar membrane (tympanic wall) cochlear nuclei Ⅱ. Multiple choice questions (two to five choices are correct, please circle the correct answers): 1. On the labyrinthine wall, there are A. promontory B. enestra vestibuli C. prominence of facial canal D. fenestra cochleae E. pyramidal eminenc 2. Receptors of balance contain A. cochlear duct B. crista ampullaris C. macula sacculi D. macula utriculi E. modiolus Ⅲ. Answer the following questions 1. Write out the position, features and divisions of the external acoustic meatus. 2. Describe the feature and structure of the wall of of the tympamic cavity. 16 3. Write out the position and divisions of the internal ear. Part ⅡThe Central Nervous System Learning Objectives You should: 了解神经系统在机体内的作用和地位。 掌握神经系统的区分。 了解神经元的形态结构及分类。 了解神经系统的基本活动方式。掌握反射弧的组成。 掌握神经系统的常用术语 Introduction Ⅰ. Function of nervous system: a master system in the living body, regulates and integrates the activities of all the bodily systems for the benefit of the organism as a whole Ⅱ. Divisions of nervous system Ⅰ) Central nervous system (CNS) Telencephalon Brain Diencephalon Cerebellum Midbrain 17 CNS Brain stem Pons n. Medulla oblongata Spinal cord Ⅱ) Peripheral nervous system (PNS) Cranial n. (12 pairs) PNS Spinal n. (31 pairs) Visceral sensory n. Visceral n. Sympathetic part Visceral motor n. Parasympathetic part cell body neurons dendrites III. Cellular organization axon neuroglia: glial cell Ⅰ) Structural classification 1. Bipolar neuron: an axon and a dendrite 2. Pseudounipolar neuron: central branch and peripheral branch 3. Multipolar neuron: an axon and two or more dendrites Ⅱ) Functional classification 1. Afferent (sensory) neuron 2. Efferent (motor) neuron 3. Association neuron (interneuron) Ⅳ. Reflex and reflex arc Ⅰ) Reflex: a reaction of the organism by the nervous system in response to a stimulus Ⅱ) Reflex arc: has five basic components receptor → afferent neurons → CNS → efferent neurons → effector Ⅴ. Basic terminology in nervous system Ⅰ) In the CNS 18 1. Gray matter and cortex ⑴Gray matter: collection of nerve cell bodies and their dendrites, gray color during fresh condition ⑵Cortex: the outermost layer of gray matter in cerebrum and cerebellum 2. White matter and medulla ⑴White matter: collection of nerve fibers, white color during fresh condition ⑵Medulla: a central core of white matter beneath cortex of cerebrum and cerebellum 3. Nucleus: a collection ( group ) of cell bodies which have the same shape and function 4. Fasciculus ( tract ): a bundle of nerve fibers which have the same origin, termination, pathway and function 5. Reticular formation: an admixture of cross-crossing fibers with larger or smaller groups of nerve cells occupying the meshes B. In the PNS 1. Ganglion: a collection of neuronal cell bodies outside the CNS 2. Nerve: a bundle of nerve fibers held together by connective tissue sheath 19 The Spinal Cord Learning Objectives You should: 掌握脊髓的位置、外形特点、脊髓节段及其与椎骨的对应关系。 掌握脊髓横切面上灰、白质的配布及各部的名称。 掌握脊髓灰质的主要核团的位置及功能性质。了解脊髓灰质的板层构筑。 掌握脊髓主要上行纤维束(薄束、楔束、脊髓丘脑束)和下行纤维束(皮质脊髓束) 的位置和功能。了解其它上、下行纤维束和固有束的位置及功能。 了解脊髓的功能。了解脊髓损伤后的临床表现。 Ⅰ. Position and external features Ⅰ) Position 20 1. Lies in vertebral canal 2. Continuous above with medulla oblongata at level of foramen magnum and ends below at the lower border of the first lumbar vertebra in the adult; at birth the cord ends at level of L3 Ⅱ) External features 1. A long cylindrical structure and slightly flattened anteroposteriorly, whose lower end tapers into a conus medullaris 2. Arising from the conus medullaris is the filum terminale, an extension of the pia mater that extends inferiorly and attaches the spinal cord to the coccyx. The lumber and sacral nerves develop long roots that extend as the cauda equina around the filum terminale. 3. Two enlargements ⑴ Cervical enlargement: corresponds to the C4 to the T1 segments ⑵ Lumbosacral enlargement: corresponds to the L2 to the S3 segments 4. Fissure and sulci: ⑴ Anterior median fissure: deep wide groove ⑵ Posterior median sulcus: deep slit like groove ⑶ Anterolateral sulcus: anterior (motor) roots emerge serially ⑷ Posterolateral sulcus: posterior (sensory) roots enter spinal cord, each bear a spinal ganglion which constitutes the first cell-station of the sensory nerves - At each intervertebral foramen the anterior and posterior roots unite to form a spinal nerve Ⅲ) Relationship of segments of spinal cord to vertebrae 1. A portion of the cord that gives rise to a pair of spinal nerve constitutes a segment. There are 31 segments in the human spinal cord: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. 2. Fetal location-until fetal month, the spinal cord is as long as the vertebral canal and extends to the leel of the fourth sacral 21 vertebra 3. The growth period and “law of descent”-after fourth fetal month, the vertebral column outgrows the spinal cord. It appears that the cord regresses to the upper lumbar levels; however, the spinal roots descend through the dural sac to the appropriate intervetrbral foramina-the law of decent. The result descending distribution of spinal root forms the cauda equina. Table 1 Relationship of segments of spinal cord to vertebrae Spinal segments Vertebral levels (spines) Upper cervical region (C1~C4) Lie opposite the corresponding vertebrae Lower cervical and upper thoracic One lower in number than corresponding vertebrae region (C5~T4) Middle thoracic region (T5~T8) Two lower in number than corresponding vertebrae Lower thoracic region (T9~T12) Three lower in number than corresponding vertebrae Lumber segments T10~T12 Sacral and coccygeal segments L1 Ⅱ. Internal structures Ⅰ) Central canal Ⅱ) Gray matter 1. Posterior horn (column): contains sensory interneurons ⑴marginal layer ⑵Substantia gelatinosa ⑶Nucleus proprius ⑷Nucleus thoracicus: in segments C8~L3 2. Intermediate zone ⑴ Intermediaolateral nucleus (lateral horn or column): lies in segments T1~L3, containing sympathetic preganglionic neurons ⑵ Sacral parasympathetic nucleus: lies in segments S2~S4, containing parasympathetic preganglionic neurons ⑶Intermediomedial nucleus: for sensation of viscera 22 3. Anterior horn (column): contain motor neurons ⑴Three kinds of neuron ① α-motor neuron: larger multipolar neuron, innervates extrafusal fibers of skeletal m., producing contraction of m. ② γ-motor neuron: smaller neuron, innervates intrafusal fibers regulating muscular tonus ③ Renshaw’s cell: negative feedback mechanism ⑵Two groups of nuclei ①Medial nuclear group: present in most segments of spinal cord, innervating axial muscles ②Lateral nuclear group: present only in cervical and lumbosacral enlargements, innervating limb muscles 4. Spinal cord gray matter is arranged in layers: there are ten Rexed’s lamina, the posterior horn is formed by lamina Ⅰ to Ⅵ, and the intermediate zone corresponding to lamina Ⅶ, and the anterior horn is composed laminae Ⅷ and Ⅸ, lamina Ⅹ is the gray matter surrounding the central canal. Table 2 Important Subdivision of Spinal Cord Gray Matter Region Lamina Nucleus Posterior horn Ⅰ Marginal layer Ⅱ Substantia gelatinosa Ⅲ, Ⅳ Nucleus proprius Ⅶ Nucleus thoracicus (C8~L3) Ⅶ Intermediolateral nucleus (T1~L3) Ⅶ Sacral parasympathetic nucleus (S2~S4) Ⅶ Intermediomedial nucleus Ⅸ Motor neuron Intermediate zone Anterior horn 23 Ⅲ) White matter 1. White matter is arranged in three funiculi, ie, ⑴ Anterior funiculus: between anterior median fissure and anterolateral sulcus ⑵Lateral funiculus: between anterolateral and posterolateral sulcuses ⑶Posterior funiculus: between posterolateral and posterior median sulcuses ⑷ Anterior white commissure: anterior to the central canal, composed of crossing fibers 2. White matter contains three kinds of fibers: ascending, descending, and fasciculus proprius Table 3 Ascending tracts Tract Site of origin Funiculus Termination Function Fasciculus Spinal ganglia Posterior Gracile nucleus Convey proprioceptive gracilis Fasciculus cuneatus below and fine touch segment T5 sensation of trunk Spinal ganglia Cuneate nucleus and limbs above segment T4 Posterior Homolateral Lateral Cerebellum spinocerebellar nucleus proprioception from thoracicus lower limb and lower Anterior Contralateral portion of trunk spinocerebellar Laminae Ⅴ~Ⅶ 24 Unconscious Laminae Ⅰ, Spinothalamic Ⅳ~Ⅶ Lateral Dorsal thalamus Pain, temperature and and simple touch anterior sensation of trunk and limbs Table 4 Descending tracts Tract Site of origin Funiculus Termination Function Lateral Cerebral cortex Lateral Laminae Voluntary movement Ⅳ~Ⅸ corticospinal Anterior Cerebral cortex Anterior anterior horn Red nucleus Lateral Laminae corticospinal Rubrospinal Excitatory of flexors Ⅶ~Ⅶ Vestibulospinal Homolateral Anterior Laminae Excitatory of extensors Ⅶ~Ⅷ vestibular nuclei Reticulospinal Reticular formation Medial longitudinal Vestibular Anterior Laminae Voluntary movement Ⅶ~Ⅷ and lateral Anterior Laminae Ⅶ~Ⅷ nuclei Coordinate neck with eye movment fasciculus Tectospinal Superior Anterior Laminae Ⅵ~Ⅷ colliculus Fasciculus Spinal cord proprius Anterior, Spinal cord lateral and Intrinsic reflex mechanism of spinal cord posterior Ⅲ. Main functions of spinal cord 1. Conduction of excitations 2. Reflex activity Ⅳ. The clinical consideration Complete hemisection of spinal cord - Brown-Sequard Syndrome Ipsilateral loss of vibration and proprioception and fine touch sensation, weakness; increased 25 tone and reflexes; contralateral loss of pain and temperature Sdudy questions Ⅰ. Single choice questions (there five choices on each question, only one is correct, please circle the correct answer): 1. In adult, the lower end of spinal cord is at the level of A. inferior border of L1 B. superior border of L1 C. inferior border of L2 D. superior border of L2 E. L3 2. The position of the 10th thoracic segment of spinal cord is at the level of A. 9th thoracic vertebra B. 8th thoracic vertebra C. 7th thoracic vertebra D. 6th thoracic vertebra E. 1st lumbar vertebra Ⅱ. Multiple choice questions (two to five choices are correct, please circle the correct answers): 1. The spinal cord A. lies in vertebral canal B. continuous with pons at level of foramen magnum C. has cervical and lumbosacral enlargement D. can be divided into 33 segments E. connected with sympathetic trunks directly 2. The fasciculi ( or tracts ) which lie in the lateral funiculus of the spinal cord are A. the fasciculus cuneatus B. the anterior corticospinal tract C. the lateral corticospinal tract D. the rubrospinal tract E. the fasciculus gracilis Ⅲ. Answer the following questions 1. Write out the position and external features of the spinal cord. 2. Write out the tne names of ascengding and descending tracts in the spinal cord. 3. Describe the divisions of the gray and white matters. 26 The brain stem Learning Objectives You should: 掌握脑干的组成和外形(包括菱形窝) 。 掌握第四脑室的位置及连通关系。 掌握脑干内神经核的分类。掌握脑神经核的机能分类、各类脑神经核的名称、位置及 其与脑神经的关系和功能。 掌握薄束核、楔束核、脑桥核、红核、黑质、顶盖前区、上丘灰质层、下丘核的位置。 了解其它非脑神经核的位置。 掌握脑干内锥体束、内侧丘系、脊髓丘系、三叉丘系、外侧丘系的位置与功能。 了解延髓锥体交叉、内侧丘系交叉、橄榄中部、脑桥下份、脑桥中份、中脑下丘、中 脑上丘水平切面的主要结构。 了解脑干网状结构的位置及功能。了解脑干各部损伤后的临床表现。 The brain stem consists of medulla oblongata, pons and midbrain. 27 Ⅰ. External features A. Medulla oblongata 1. Ventral surface a) Pyramid: contain pyramidal tract (corticospinal tract) b) Decussation of pyramid: formed by crossing fibers of corticospinal tract c) Olive: produced by underlying inferior olivary nucleus d) Anterolateral sulcus: rootlets of hypoglossal nerve emerge from it e) Retroolivary sulcus: rootlets of glossopharyngeal, vagus and accessory nerves emerge from it 2. Dorsal surface a) Lower portion ⑴Gracile tubercle: produced by underlying gracile nucleus ⑵Cuneate tubercle: marks the site of cuneate nucleus ⑶ Inferior cerebellar peduncle: formed by fibers which connect spinal cord and medulla with cerebellum ⑷Obex: the apex of v-shaped caudal fourth ventricle b) Upper portion: forms the lower half of rhomboid fossa B. Pons 1. Ventral surface a) Basilar part: convex b) Basilar sulcus: a groove along the midline, lodges the basilar artery c) Bulbopontine sulcus: from medial to lateral, the abducent, facial and vestibulocochlear nerves appear d) Middle cerebellar peduncle: a broad transverse band of nerve fibers which enter the corresponding cerebellar hemisphere e) Trigeminal nerve: emerges from the junction of basilar part and middle cerebellar peduncles f) Pontocerebellar trigone: the junction of medulla, pons and cerebellum 28 2. Dorsal surface — forms upper part of rhomboid fossa a) Superior cerebellar peduncle b) Superior medullary velum c) Trochlear nerve: lies above superior medullary velum C. Midbrain 1. Ventral surface a) Crus cerebri: formed by descending fibers b) Interpeduncular fossa: a deep depression, oculomotor nerves emerge from medial of crus cerebri c) Posterior perforated substance: the floor of interpeduncular fossa, through which pass central branches of posterior cerebral artery 2. Dorsal surface a) Superior colliculus: constitute centers for visual reflexes b) Inferior colliculus: associated with auditory pathway c) Brachium of superior and inferior colliculi: interconnect the superior and inferior colliculi to lateral and medial geniculat bodies respectively D. Fourth ventricle 1. Position: situated ventral to cerebellum, and dorsal to pons and cranial half of medulla 2. Floor-- rhomboid fossa a) Boundaries (1) Inferolateral: gracile and cuneate tubercles, inferior cerebellar peduncle (2) Superolateral: superior cerebellar peduncle (3) Lateral recess b) Features (1) Median sulcus (2) Sulcus limitans (3) Vestibular area: a triangular area lateral to sulcus limitans, overlies vestibular nuclei (4) Acoustic tubercle: lies on lateral angle of vestibular area, overlying dorsal cochlear nucleus (5) Medial eminence: a longitudinal elevation between median sulcus and sulcus limitans (6) Striae medullares (7) Facial colliculus: elongated swelling, which overlies nucleus of abducent n. 29 and genu of facial nerve (8) Hypoglossal triangle: on medial eminence, below striae medullares, verlying hypoglossal nucleus (9) Vagal triangle: overlies dorsal nucleus of vagus nerve (10) Funiculus separans (11) Area postrema (12) Locus ceruleus 2. Roof: V- shaped as seen in sagittal a) Anterior part: formed by superior cerebellar peduncle and superior medullary velum b) Posterior part: formed by inferior medullary velum and choroid plexus of fourth ventricle c) Three apertures (1) Median aperture of fourth ventricle (2) Two lateral apertures of fourth ventricle Ⅱ. Internal structures A. Gray matter 1. Cranial nerve nuclei Table 1 Somatic motor nuclei Nucleus Site Nucleus of oculomotor n. Midbrain Cranial n. Ⅲ Function Supreior, inferior,and medial recti, inf. obliquus, levator palpebrae superioris Nucleus of trochlear n. Midbrain Ⅳ Superior obliquus Nucleus of abducent n. Pons Ⅵ Lateral rectus Nucleus of hypoglossal n. Medulla Ⅻ Muscles of tongue 30 Table 2 Special visceral motor nuclei Nucleus Site Cranial n. Function Motor nucleus of Pons Ⅴ Masticatory muscles Pons Ⅶ Facial m., platysma, posterior trigeminal n. Nucleus of facial n. belly of digastric, stylohyoid, stapedius Medulla Nucleus ambiguus Ⅸ,Ⅹ.Ⅺ Skeletal m. of pharynx, larynx and upper part of esophagus Medulla-cervical Accessory nucleus Ⅺ Sternocleidomastoid, trapezius cord Table 3 General visceral motor nuclei Nucleus Site Cranial n. Function Accessory oculomotor Midbrain Ⅲ Sphincter pupillae and ciliary m. Pons Ⅶ Submandibular, sublingual and nucleus Superior salivatory nucleus lacrimal glands Inferior salivertory nucleus Medulla Ⅸ Parotid gland Dorsal nucleus of vagus n. medulla Ⅹ Many cervical, thoracic and abdominal viscera Table 4 Visceral afferent nuclei ( general and special ) 31 Nucleus Site Cranial n. Function Nucleus of solitary tract Medulla Ⅶ,Ⅸ,Ⅹ Taste and visceral sensation Table 5 General somatic afferent nuclei Nucleus Site Cranial n. Function Mesencephalic nucleus of Midbrain Ⅴ Proprioception of head Pontine nucleus of trigeminal n. Pons Ⅴ Tactile sensation of head Spinal nucleus of trigeminal n. Medulla Ⅴ Pain and temperature sense trigeminal n. of head Table 6 Special somatic afferent nuclei Nucleus Site Cranial n. Function Cochlear nuclei Pons and medulla Ⅷ Sense of hearing Vestibular nuclei Pons and medulla Ⅷ Sense of equilibrium 2. Non-cranial nerve nuclei Nucleus Site Gracile nucleus Medulla (underneath gracile tubercle) Cuneate nucleus Medulla (underneath cuneate tubercle) Superior olivery nucleus Pons Pontine nucleus pons Nucleus of inferior colliculus Midbrain Gray matter layers of superior colliculus Midbrain Red nucleus Midbrain Substantia nigra Midbrain Pretectal area Midbrain B. White matter 1. Ascending tracts a) Medial lemniscus The fibers in fasciculus gracilis and cuneatus end in the gracile and cuneate nuclei. The axons from latter cells pass ventromedially and cross the midline forming the decussation of the medial lemniscus. After crossing the midline, fibers turn upwards between midline and inferior olivary 32 nuculeus, behind pyramidal tract, and run cranially through the trapezoid body in the anterior margin of the tegmentum of pons, thereafter, they turn upwards and ascend lateral to the red nucleus in tegmentum of midbrain, to reach the ventral posterolateral nucleus (VPL) of dorsal thalamus. b) Spinal lemniscus In the medulla oblongata the lateral and anterior spinothalamic tracts become blended to form spinal lemniscus which passes upward at dorsolateral of inferior olivary nuculeus, through pons and midbrain, lateral to medial lemniscus, to reach the ventral posterolateral nucleus (VPL) of dorsal thalamus. c) Trigeminal lemniscus The spinal nucleus and pontine nucleus of trigeminal nerve give rise the axons to the opposite side to join the trigeminal lemniscus running through the pons and midbrain to the ventral poseromedial nucleus (VPM) of dorsal thalamus. d) Lateral lemniscus Fibers from cochlear nuclei run transversely across midline to the opposite side and turn upward to form the lateral lemniscus . The transversely running fibers form the trapezoid body which occupy the ventral potion of the tegmentum of pons where they mingle with the fibers of medial lemniscus, crossing them at right angle. They then pass through lateral to the medial lemniscus in the midbrain, to reach the inferior collicul 2. Descending tracts a) Corticospinal tract This is a long pathway originating in the cerebral cortex. It descends through the middle 3/5 of crus cerebri. In the pons where they are separated into several small bundles by transversely disposed ponticerebellar fibers. Blower pons the fibers are closely grouped together in the pyramids on the ventral aspect of medulla oblongata. In the lower half of medulla, the majority of corticospinal fibers cross to the opposite side of the brain stem, forming the decussation of pyramid. These decussating fibers turn downward to descend in the lateral funiculus of spinal cord as the lateral corticospinal tract. The uncrossed fibers retain their ventromedial position and descend in the anterior funiculus of spinal cord as the anterior corticospinal tracts. b) Others: rubrospinal tract, tectospinal tract, vestibulospinal tract, and reticulospinal tract C. Reticular formation of brain stem 1. Ascending reticular activating system (ARAS) 33 2. Motor central and vital centres a) Reticulospinal tract b) Cardiovascular center and respiratory center 3. Serotonergic rapheal nuclei D. Central canal Centra canal → fourth ventricle → mesencephalic aqueduct Ⅲ. The characters of internal structure of brain stem A. Medulla oblongata 1. Upper part (open part) a) Appearance of inferior olivary nuculeus and inferior cerebellar peduncle b) Enlargement of central canal to form the fourth ventricle floor 2. Lower part (closed part) : two decussations--decussations of medial lemniscus and pyramid Decussations of pyramid Decussations of medial lemniscus Inferior olivary nuculeus B. Pons 1. Tegmentum of pons: directed upward continuation of medulla oblongata, excluding the pyramids. The central gray matter is spread out to form the floor of the upper part of the fourth ventricle , a number of new cranial nerve nuclei are present. 2. Basilar part: contain both longitudinal and transverse fibers intermixed with pontine nuclei C. Midbrain 1. Rectum of midbrain: includes superior and inferior colliculi 2. Cerebral peduncle a) Tegmentum: contain ascending tracts, central gray matter, recticular formation and so 34 on b) Substentia nigra c) Crus cerebri: the pyramidal tract occupy the middle three-fifths of the crus, the frontopontine tract occupy the medial one-fifth and tempo-occipito-pontine tract the lateral one-fifth of the crus Sdudy questions Ⅰ. Single choice questions (there five choices on each question, only one is correct, please circle the correct answer): 1.The cranial nerves nuclei in the medulla oblongata don’t include A. nucleus of hypoglassal nerve B. nucleus ambiguus C. abducens nucleus D. spinal nucleus of trigeminal nerve E. nucleus of solitary tract 2.The decussation of medial lemniscus A. represents the crossing of motor tract B. lies below the decussation of pyramid C. lies at the level of the facial colliculus D. formed by the crossing fibers of spinal lemniscus E. formed by the crossing fibers which arise from the gracile and cuneate nuclei Ⅱ. Multiple choice questions (two to five choices are correct, please circle the correct answers): 1.The nuclei in the midbrain are A. accessory nucleus of oculomotor nerve B. nucleus of trochlear nerve C. pontine nucleus of trigeminal nerve D. mesencephalic nucleus of trigeminal nerve 35 E. gracile nucleus 2.The nuclei related to the vagus nerve A. dorsal nucleus of vagus nerve B. inferior salivatory nucleus C. nucleus ambiguus D. nucleus of solitary tract E. nucleus of hypoglossal nerve Ⅲ. Answer the following questions 1.Write out the names of the somatic motor nuclei of the brain stem and the meatus or foramina from which their fibers leave the skull. 2.Write out the names of the somatic motor nuclei of the brain stem and the meatus or foramina from which their fibers leave the skull. 3.Write out the names and functions of lemnisci of the brain stem. The Cerebellum Learning Objectives You should: 掌握小脑的位置、外形、分叶和机能分区。 了解小脑核的名称、位置。 了解小脑的纤维联系与功能。 Ⅰ. Position, external features and lobs A. Potion: lies above and behind the medullar and pons and occupies posterior cranial fossa B. External features 36 1. Consists of two cerebellar hemisphere united in the midline by the vermis 2. Three peduncles connect each hemisphere to the three parts of brainstem a) Inferior cerebellar peduncle connect with medulla and with spinal cord, contain both afferent and efferent fibers b) Middle cerebellar peduncle connect with pons, contain afferent fibers c) Superior cerebellar peduncle connect with midbrain, contain mostly efferent fibers 3. Tonsil of cerebellum: two elevated masses on inferior surface of hemispheral portion just nearby foramen magnum C. Lobs 1. Two deep fissures a) Primary fissure b) Posterolateral fissure 2. Three lobs a) Flocculonodular lobe: flocculus and nodule b) Anterior lobe corpus of cerebellar c) Posterior lobe Ⅱ. Internal structures A. Gray matter 1. Cerebellar cortex 2. Cerebellar nuclei a) Dentate nucleus b) Fastigial nucleus 37 c) Interposed nucleus ⑴ Emboliform nucleus ⑵ Globose nucleus B. White matter--medullary center Ⅲ. Connections and function of cerebellum Three functional divisions Vestibulocerebellum ( archicerebellum ): Flocculonodular lobe Spinocerebellum ( paleocerebellum ): vermis and intermediate zone Cerebrocerebellum (neocerebellum ): lateral zone A. Vestibulocerebellum 1. Connections a) Afferents: receive input from vestibular nuclei and primary vestibular b) Efferents: projects to the vestibular nucleus → vestibulospinal tract and medial longitudinal fasciculus → motor neurons of anterior horn 2. Function: involved in eye movements and maintain balance B. Spinocerebellum 1. Connnection a) Afferents: receive somatic sensory information via spinocerebellar tracts b) Efferents: (1) Vermis projects to the fastigial nucleus → vestibular nuclei and reticular formation → vestibulospinal tract and reticulospinal tract → motor neurons of anterior horn (2) Intermediate zone projects to the interposed nuclei → ①contralateral red nucleus → rubrospinal tract →motor neurons of anterior horn ② contralateral VI →cerebral cortex→ coticospinal tract→motor neurons of anterior horn 2. Function: play an important role in control of muscle tone and coordination of muscle movement on the same side of the body C. Cerebrocerebellum 1. Connection a) Afferents: receives input from the cerebral cortex via a relay in pontine nuclei b) Efferents: projects to dentate nucleus → VI → primary motor cortex → corticospinal tract → motor neurons of anterior horn 3. Function: participates in planning movements 38 Sdudy questions Ⅰ. Single choice questions (there five choices on each question, only one is correct, please circle the correct answer): 1. The tonsil of cerebellum A. are two elevated masses of the anterior lobe B. is a part of the archiocerebellum C. is a part of the neocerebellum D. its fibers project to the red nucleus E. lies below the foramen magnum 2. Which is wrong about cerebellum A. it lies in posterior cranial fossa B. the anterior lobe is called cerebellar hemisphere C. cerebellum has two cerebellar hemisphere D. there are three pairs cerebellar peduncles E. the dentate nucleus is the largest cerebellar nuclei Ⅱ. Multiple choice questions (two to five choices are correct, please circle the correct answers): 1. Which statements are correct about cerebellum A. The cerebellum is located in the posterior cranial fossa B. The cerebellum is divide into flocculonodular, ant. and pos. lobe C. The dentate nucleus is the largest nucleus of the cerebellar nuclei D. There are three pairs of cerebellar peduncles E. The sup. cerebellar peduncle consists mainly of the efferent fibers Ⅲ. Answer the following questions 1. Write out the positionand external features of the cerebellum. 2. Write out the names of cerebellar nuclei. 39 The Diencephalon Learning Objectives You should: 掌握间脑的位置、分部及各部的组成和位置。 掌握第三脑室的位置与连通。 了解背侧丘脑核团的划分。掌握特异性中继核团的名称、纤维联系和功能(包括后丘 脑) 。 掌握下丘脑的主要核团及其与垂体的关系。了解下丘脑的功能。 Ⅰ. Position and subdivision A. Position: Lies between midbrian and cerebrum, almost entirely surrounded by cerebral hemisphere 40 B. Subdivision 1. Doral thalamus 2. Epithalamus: includes thalamic medullary stria, habenular trigone , habenular commissure, pineal body and posterior commissure 3. Hypothalamus 4. Metathalamus 5. Subthalamus: transition zone between diencephalons and tegmentum of midbrain, contain subthalamic nucleus, parts of red nucleus and substantia nigra Ⅱ. Dorsal thalamus A. External features 1. A large egg-shaped nucleus mass, it’s anterior end called anterior thalamic tubercle, the posterior end called pulvinar 2. Right and left portion of thalamus are joined by interthalamic adhesion B. Classification of nuclei of dorsal thalamus The thalamus has anterior, medial and lateral divisions defined by internal medullary lamina Topographical Subdivisions of the Thalamus and Their Principal Nuclei Subdivision Principal Nuclei Common abbreviation Ant. nuclear group Med. nuclear group Lat. nuclear group Dorsal tier Lateral dorsal LD Lateral posterior LP Pulvinar Ventral tier Ventral anterior VA Ventral intermediate VL Ventral posterior VP Ventral posterolateral VPL Ventral posteromedial VPM 41 C. Functional subdivision 1. Nonspecific relay nuclei:, a) Midline nucleus group b) Intralaminar nuclear group c) Thalamic reticular nucleus receive afferents from rhinencephalon and reticular formation of brain stem, project mainly to hypothalamus and corpus striatum 2. Association nuclei a) Anterior nuclear group b) Medial nuclear group c) Dorsal tier of lateral nuclear group Receive input from many converging sours and in turn project widely to the association areas of cerebral cortex 3. Special relay nuclei a) Vent. anterior nucleus receiving dentate nucleus, globus pallidus and substantia nigra to b) Vent. intermediate nucleus motor cortex c) Vent. posteromedial nucleus: receives trigeminal lemniscus and teste fibers d) Vent. posterolateral nucleus: receives medial lemniscus and spinal lemniscus projects to primary somatosensory area via central thalamic radiation Ⅲ. Metathalamus A. Medial geniculate body (MGN) 1. Relay station of audition 2. Receive fibers from inferior colliculus 3. Projects to auditory area via acoustic radiation B. Lateral geniculate body (LGN) 1. Relay station of vision 2. Receive fibers from optic tract 3. Projects to visual area via optic radiation Ⅳ. Hypothalamus: lies ventral to thalamus A. Boundaries 1. Superiorly: hypothalamic sulcus 42 2. Inferiorly: optic chiasma, tuber cinereum, infundibulum and mamillary body 3. Anterior: lamina terminalis 4. Posterior: continues with midbrain tegmentum B. Subdivisions and important nuclei 1. Preoptic region 2 . Supraoptic region a) Supraoptic nucleus: produce antidiuretic hormone (ADH, or vasopression) b) Paraventricular nucleus: produce oxytocin 3. Tuberal region a) Infundibular nucleus b) Ventromedial nucleus c) Dorsomedial nucleus 4. Mamillary region a) Mamillary nucleus b) Posterior hypothalamic nucleus C. Connection 1. Connects with limbic system a) Septal area→terminal stria (ST) and ventral amygdaloid pathway (VAP) → amagdaloid body b) Hippocampus → fonix (F) → mamillary body c) Septal area → medial forebrain bundle (MFB)→ midbrain tegmentum 2. Connects with brainstem and spinal cord a) Septal area → medial forebrain bundle(MFB) → midbrain tegmentum b) Periventricular gray matter → dorsal longitudinal fasciculus (DLF) → central gray matter and midbrain tegmentum 3. Connects with dorsal thalamus Mamillary body→mamillothalamic tract (MTT) → anterior nuclear group of thalamus 4. Connects with hypophysis a) Supraoptic nucleus (vasopressin) →supraopticohypophyseal tract →posterior lobe of hypophysis b) Paraventicular nucleus (oxytocin) →paraventriculohypophyseal tract→posterior lobe of hypophysis 43 c) Parvicellular neurons in the arcuate nucleus and nearby region of the walls of the third ventricle secrete releasing and inhibiting hormones → tuberoinfundibular tract →portal vein of hypophsis → anterior lobe of hypophsis D. Function: regulates functions of neuroendocrine system and autonomic nervous system Ⅴ. Third ventricle A. Position: a narrow ventricle cleft lies within diencephalons B. Boundaries 1. Roof: choroids plexus 2. Floor: optic chiasma, tuber cinereum, infundibulum and mamillary body 3. Anterior: lamina terminalis 4. Posterior: continuous with mesencephalic aqueduct 5. Lateral wall: dorsal thalamus and hypothalamus C. Communication Third ventricle →mesencephalic aqueduct → fourth ventricle Sdudy questions Ⅰ. Single choice questions (there five choices on each question, only one is correct, please circle the correct answer): 1. The ventral posterolateral nucleus of thalamus receivess fibers from A. spinal lemniscus B. lateral lemniscus C. medial lemniscus D. hypothalamus E. trigeminal lemniscus 2. The structures belonging to the hypothalamus include A. optic chiasma B. mamillary body C. paraventricular nucleus D. ventral posterior nucleus E. medial geniculate body Ⅱ. Multiple choice questions (two to five choices are correct, please circle the correct answers): 1. The diencephalon consists of 44 A. epithalamus B. hypothalamus C. subthalamus D. dorsal thalamus E. metathalamus 2. The specific relay nuclei in the diencephalon are A. the ventral anterior nucleus of thalamus B. the ventral posterolateral nucleus of thalamus C. the lateral geniculate body D. the anterior nuclear group of thalamus E. the supraoptic nucleus Ⅲ. Answer the following questions 1. Write out the divisions of the diencephalons. 2. Write out the names of specific nuclei of diencephalon and which fibres they receive. The Telencephalon Learning Objectives You should: 掌握大脑半球的主要沟裂、分叶和各叶的主要沟回。 掌握第 I 躯体运动区、第 I 躯体感觉区、视区、听区的位置及功能定位。掌握语言中 枢的位置。 掌握基底核的组成和位置。 掌握侧脑室的形态分部和各部的位置。 了解大脑半球白质纤维的分类。 掌握内囊的位置、分部及各部所通过的主要纤维束。了解内囊损伤后的临床表现。 了解嗅脑和边缘系统的组成及功能。 Ⅰ. External feature 45 The telencephalon consists of right and left cerebral hemisphere, partially separated by a deep sagittal grove, cerebral longitudinal fissure. At the button of this fissure, the hemispheres are connected with each other by the great central white commissure, the corpus callosum. The cerebral transverse fissure intervenes between the hemispheres and the cerebellum. Each hemisphere has three surfaces: superolateral, medial and inferior. About 4 cm in front of the occipital pole on the inferior border there is an indentation—the preoccipital notch. The surface of the cerebral cotex is folded into gyri (ridges) separated by sulci (groove). Gyri increase the surface area, thereby accommodating more functional columns. Although the pattern of gyri and sulci is variable, the location of some ridges and grooves is remarkably consistent, providing convenient landmarks. Central sulcus A. Three sulci Lateral sulcus Parietooccipital sulcus Frontal lobe Parietal lobe B. Five lobes Temporal lobe Occipital lobe Insular lobe Ⅱ. Sulci and gyri A. Superolateral surface 1. Frontal lobe: precentral sulcus, superior frontal sulcus, inferior frontal sulcus, precentral gyrus, superior frontal gyrus, middle frontal gyrus and inferior frontal gyrus 2. Parietal lobe: postcentral sulcus, postcentral gyrus, intraparietal sulcus, superior parietal lobule, inferior parietal lobule, supramarginal gyrus, angular gyrus 3. Temporal lobe: superior temporal sulcus, inferior temporal sulcus, superior temporal gyrus, middle temporal gyrus, inferior temporal gyrus and transverse temporal gyri 46 B. Medial surface corpus callosum, callosal sulcus, cingulate gyrus, cingulate sulcus, marginal ramus, paracentral lobule, calcarine sulcus , cuneus, lingual gyrus C. Inferior surface olfactory bulb, olfactory tract, olfactory trigone, anterior perforated substance, collateral sulcus, occipitotemporal sulcus, medial occipitotemporal gyrus, lateral occipitotemporal gyrus, hippocampal sulcus, parahippocampal gyrus, uncus, hippocampus, dentate gyrus, hippocampal formation D. Functional location of the cerebral cortex archicortex (hippocampal formation) Cerebral cortex paleocortex (rhinencephalon ) 3 cell layers neocortex (most of cerebral cortex) 6 cell layers 1. Primary motor area a) Located in precentral gyrus and anterior portion of paracentral lobule b) Characters (1) Representation is inverted, but head and face are upright (2) A body part is represented by a cortical area proportional to its use rather than its size c) Receiving fibers from postcentral gyrus, VA, VL and VPL, sending out fibers to form pyramidal tract, controlling voluntary movements 2. Primary somatosensory area a) Lies in postcentral gyrus and posterior portion of paracentral lobule b) Sensory representation, like motor area, is crossed and inverted c) Receiving and interpret sensation from opposite side of body 3. Visual area a) Lie on either side of calcarine sulcus in medial surface of occipital lobe 47 b) Visual cortex of one hemisphere receives impression from temporal part of retina of same side and nasal part of opposite side c) Lesions of visual cortex produce contralateral homonymous visual field defections 4. Auditory area a) Located in transverse gyri b) Receive auditory information from both ears 5. Vestibular area: located in front of superior temporal gyrus 6. Olfactory area: located near the uncus 7. Taste area: located at frontal operculum 8. Language area: it is dominant in left hemisphere in right-handed person a) Motor speech area (1) Located in posterior portion of inferior frontal gyrus b b a A (2) damage: motor aphasia a b) Writing area (1) Located in posterior portion of middle frontal gyrus (2) Damage: agraphia c) Auditory speech area (1) Located in posterior portion of superior temporal gyrus (2) Lesion: sensory aphasia d) Visual speech area (1) Located in angular gyrus (2) Lesion: alexia Ⅲ. Internal structures A. Lateral ventricle: C-shaped 1. Position: located in cerebral hemispheres 2. Four parts a) Central part: lies in parietal lobe b) Anterior horn: extends into frontal lobe c) Posterior horn extend into occipital lobe d) Inferior horn: extend into temporal lobe 48 c c d 3. Communication lateral ventricle → interventricular foramen → third ventricle C. Basal nuclei: deep within base of cerebral hemisphere globus pallidus: paleostriatum lentiform nucleus putamen 1. Corpus striatum neostriatum caudate nucleus 2. Claustrum 3. Amygdaloid body Ⅳ. White matter: cerebral medullary A. Association fibers: run between gyri within the same hemisphere 1. Cerebral arcuate fibers 2. Superior and inferior longitudinal fasciculi 3. Uncinate fasciculus 4. Cingulum B. Commissural fibers: run between left and right hemisphere 1. Corpus callosum: rostrum, genu, trunk, splenium 2. Anterior commissure 3. Fornix and commissure of fornix C. Projection fibers: connect cortex with lower part of brain and spinal cord include both ascending and descending fibers ★ Internal capsule 1. Position: a thick lamina of white matter lying between caudate nucleus, thalamus and lentiform nucleus 2. Three parts a) Anterior limb of internal capsule (1) Lies between caudate nucleus and lentiform nucleus (2) Containing frontopontine tract and anterior thalamic radiation b) Genu of internal capsule 49 and they (1) Is angle at which anterior and posterior limbs meet (2) Containing corticonuclear tract c) Posterior limb of internal capsule (1) Lies between thalamus and lentiform nucleus (2) Contain corticospinal tract, corticorubral tract, central thalamic radiation, parieto-occipito-temporo-pontine tract, acoustic radiation and optic radiation Ⅴ. Limbic system A. Composition 1. Limbic lobe: includes septal area, cingulated gyrus, parahippocampal gyrus, hippocampus, dentate gyrus, temporal pole, anterior part of insular lobe and so on 2. Associated subcortical nuclei: amygdaloid body, septal nuclei, hypothalamus, epithalamus, anterior nucleus group of thalamus, tegmentum of midbrain B. Function: concerned with visceral activities, olfaction, emotion and memory, so this system is called ‘visceral brain’ Sdudy questions Ⅰ. Single choice questions (there five choices on each question, only one is correct, please circle the correct answer): 1.The visual speech area is located in A. posterior portion of superior frontal gyrus B. posterior portion of middle frontal gyrus C. posterior portion of inferior frontal gyrus D. calcarine sulcus E. angular gyrus 2. The left side of inferior 1/3 of postcentral gyrus receives the fibers from A. left spinal lemniscus B. right spinal lemniscus C. left trigeminal lemniscus D. right trigeminal lemniscus E. leftt ventral posteromedial nucleus Ⅱ. Multiple choice questions (two to five choices are correct, please circle the correct answers): 50 1. The basa nuclei of cerebrum include A. claustrum B. substantia nigra C. amygdaloid body D. lentiform nucleus E. caudate nucleus 2. The commissural fibers between left and right cerebral hemisphere A. cingulum B. corpus callosum C. anterior commissure D. cerebral arcuate fibers E. commissure of fornix Ⅲ. Answer the following questions 1. Describe the positions and functional localization of the primary motor area , primary somatosensory area, visual area, auditory area, language area of the cerebral cortex. 2. Write out the organization andposition of the basal ganglia. 3. Write out the position, divisions of the internal capsule and the name of main nerve fibrous tracts in it. The Nervous pathway Learning Objectives You should: 感觉传导通路 掌握躯干、四肢意识性本体觉和精细触觉传导通路的组成,各级神经元胞体所在 部位,纤维束在中枢各部的位置及向大脑皮质投射的部位。 了解躯干、四肢非意识性本体感觉传导通路。 掌握躯干、四肢及头面部痛温觉和粗触压觉传导通路的组成,各级神经元胞体所 在的部位,纤维束在中枢各部的位置及向大脑皮质投射的部位。 掌握视觉传导通路的组成,各级神经元胞体所在部位,纤维部分交叉(视交叉) 的情况,在内囊的位置和向大脑皮质投射的部位。了解视觉传导通路不同部位损 伤后的视野变化。掌握瞳孔对光反射的通路。了解该通路不同部位损伤后瞳孔对 光反射的变化。 51 了解听觉传导通路的组成。 运动传导通路 掌握上、下运动神经元的位置。 掌握皮质脊髓束在中枢各部的位置、纤维交叉部位及其与下运动神经元联系的状 况。 掌握皮质核束在中枢各部的位置及其对脑神经运动核的管理。 了解上、下运动神经元损伤后的临床表现。 掌握锥体外系的概念。了解主要的锥体外系通路。 Receptor → afferent neuron → central nervous system → efferent neuron →effector Sensory pathways Motor pathways Ⅰ. Sensory pathways A. Proprioceptive pathways 1. Conscious proprioceptive and fine touch pathway of trunk and limbs It is a three-neuron chain that transmits fine touch, vibratory and transmits proprioceptive information from the trunk and limbs to the cerebral cortex. a) The 1°( first-order ) neurons: pseudounipolar neurons, located in spinal ganglion, the peripheral branches run through the corresponding spinal nerve to the sensory receptors in skin, muscles, joints or tendons, the central branches enter spinal cord by way of dorsal roots and join the posterior funiculus on the same side. Thus fibers entering below the midthoracic level spinal cord form medially-placed fasciculus gracilis which extends whole length of cord, while whose entering above this level form the fasciculus cuneatus which is confined to upper part of cord. The fibers of both fasciculi continue upwards into brain stem and terminate about the middle of medulla by synapsing with the cells of gracile or cuneate nuclei. b) The 2°(second-order ) neurons: located in gracile and cuneate nuclei, the axons of 52 the 2°neurons pass ventromedially and cross the midline forming the decussation of medial lemniscus. After crossing the midline, fibers turn upwards on the opposite side as the medial lemniscus between midline and inferior olivary nucleus, behind pyramidal tract, and run cranially through the trapezoid body in the anterior margin of the tegmentum of pons, thereafter, they turn upwards and ascend lateral to the red nucleus in tegmentum of midbrain, to reach the dorsal thalamus, where they synapse with the 3°neurons in ventral posterolateral nucleus (VPL) of dorsal thalamus c) The 3°(third –order) neurons: VPL nucleus of dorsal thalamus send their axons by way of the central thalamic radiations through posterior limb of internal capsule to cortex of superior and middle parts of postcentral gyrus and to posterior part of paracentral lobule, some fibers project to precentral gyrus Muscles 1°neuron tendons joints central branches enter posterior funiculus of spinal cord spinal ganglion skin f. entering below T5 level of cord form fasciculus gracilis f. entering above T4 level of cord form fasciculus cuneatus 2°neuron ╳ decussation of medial lemniscus 〈○ ascending as medial lemniscus gracile and cuneate nuclei 3°neurons central thalamic radiation gyrus, posterior part of paracentral lobule 〈○ VPL superior and middle part of postcentral via post. limb of internal capsule and precentral gyrus 2. Unconscious proprioceptive pathway Muscles thoracic nucleus 〈○ joins tendons posterior spinocerebellar tract spinal ganglion lamina Ⅴ-Ⅶ anterior spinocerebellar tract 53 (lumbosacral enlargement) (cross and uncross) inferior cerebellar peduncle paleocortex of cerebellum superior cerebellar peduncle B. Superficial sensory pathway 1. Pain, temperature and simple touch pathway of trunk and limbs Skin of 1°neuron central branches enter spinal cord 2°neuron 〈○ trunk and limbs spinal ganglia LaminaⅠ,Ⅳ~Ⅶof spinal cord ╳ slope obliquely upward 1-2 segments, decussate through anterior white commissure lateral spinothalamic tract (for pain and temperature ) in lateral funiculus anterior spinothalamic tract ( for crude touch and pressure) in anterior funiculus 3°neurons central thalamic radiation superior and middle part of postcentral gyrus, poterior 〈○ 54 via posterior limb of internal capsule VPL part of paracentral lobule 2. Pain, temperature and simple touch pathway of head and face Skin, mucosa 1°neuron central processes enter pons of head and face trigeminal ganglion spinal tract of trigeminal nerve 2°neuron ╳ pontine nucleus of trigeminal never ( tactile ) trigeminal lemniscus 〈○ spinal nucleus of trigeminal nerve( pain and temperature ) 3°neurons central thalamic radiation inferior part of postcentral gyrus 〈○ VPM via posterior limb of internal capsule C. Visual pathway and pupillary reflexes ※Visual filed: when both eyes are in use and directed forward, the area which can be seen, that is the visual field, may be divided into two parts, the nasal half and temporal half of visual fields. Because light must pass though the refractive media of the eye the image of an object in the visual field on the retina is reversed. The lens of each eye projects an inverted and reversed visual field onto each retina. Thus , the temporal half of visual fields project onto the nasal halves of each retina; the nasal half of visual fields project onto the temporal halves of each retina. In each case, light from the lower half of the visual field falls on the upper retinal quadrants and light from the upper half of the visual field on the lower retinal quadrants. ※ Pupillary reflex: When light is shone into one eye the pupils of both eyes constrict equally. The response in the eye stimulated is the direct pupillary light reflex, while that in the opposite 55 eye is known as the indirect pupillary light reflex. 1. Visual pathway 1°neuron Rod and cone cells 2°neuron ○ optic nerve 〈○ bipolar cells ganglion cells optic chiasma ( nasal fibers of retina cross, temporal fibers uncross ) ╳ → optic tract 3°neurons optic radiation 〈○ visual area lateral geniculate body via posterior limb of internal capsule The effects of lesions of the visual pathway Site of lesion Deficit Left Right Left optic nerve Blindness of left eye ● ○ Midline of optic chiasma Bitemporal hemianopsia(tunnel vision) ◐ ◑ Lateral part of optic chiasma Nasal hemianopia of left eye ◑ ○ Left optic tract Right homonymous hemianopsia ◑ ◑ 2. Pupillary reflexes retina→optic nerve→optic chiasma→both optic tracts→brachium of superior colliculus both accessory oculomotor nuclei 〈○ 〈○ sphincter pupil 〈○ pretectal area ciliary ganglia ciliary muscle B. Auditory pathway cochlear nerve spinal organ ○ 〈○ bipolar neuron of cochlear ganglion ╳ trapezoid body cochlear nuclei brachium of inferior colliculus 〈○ lateral lemniscus inferior colliculus hearing reflex 56 anterior horn 〈○ superior colliculus tectospinal tract acoustic radiation transverse temporal gyrus 〈○ medial geniculate body via posterior limb of internal capsule Ⅱ. Motor pathway A. Pyramidal system: consists of sets of two neurons ① Upper motor neuron: composed of pyramidal cells which located in precentral gyrus and anterior part of paracentral lobule and their axons which form pyramidal tract ② Lower motor neuron: composed of cranial motor nuclei or spinal cord anterior horn and their axons 1. Corticospinal tract upper motor neuron corticospinal tract ○ pyramidal cells of superior and via posterior limb of internal capsule, middle parts of precentral gyrus lateral part of middle 3/5 of crus cerebri, and anterior part of paracentral basilar part of pons, lobule pyramid of medulla oblongata 75%—90% of fibers cross ╳ decussation of pyramid lateral corticospinal tract 10%—25% of fibers uncross anterior corticospinal tract → some fibers cross and some uncross lower motor neuron 57 〈○ skeletal muscles of trunk and limbs motor neurons of anterior horn 3. Corticonuclear tract upper motor neuron corticonuclear tract ○ pyramidal cells of inferior via genu of internal capsule, part of precentral gyrus medial part of middle 3/5 of crus cerebri lower motor neuron skeletal muscles of 〈○ bilateral oculomotor, trochlear, trigeminal motor, abducens, head and neck superior part of facial, ambiguus and accessory nuclei; contralateral inferior part of facial and hypoglossal nuclei B. Extrapyramidal system 1. Extrapyramidal system includes all descending ( motor ) tracts other than corticospinal and corticonuclear tracts. 2. Function a. Regulate muscle tone b. Coordinate muscular activities c. Maintain normal body posture and produce habitual and rhythmic movement 3. main pathways cortex ↙ cortex ↖ ↙ 58 ↖ corpus striatum → thalamus pons ↑↓ thalamus ↘ substantia nigra ↗ cerebellum ↓ ↓ reticular formation red nucleus ↓ ↓ reticulospinal tract rubrospinal tract ↘ ↙ motor neurons in anterior horn Effects of Upper (UMN) and Lower (LMN) Motor Neuron Damage UMN damage ( supranuclear paralysis ) LMN damage ( infranuclear paralysis ) Paralysis Spastic Flaccid Muscle tone Increased↑ Decreased↓ Deep tendon reflexes Increased↑ Decreased Pathological reflexes Positive (+) Negatively (-) amyotrophy Indistinctly Distinctly Sdudy questions Ⅰ. Single choice questions (there five choices on each question, only one is correct, please circle the correct answer): 1. Which is the right about the corticospinal tract A. arises from the cerebral cortex of the posterior central gyrus B. passes through the genu of the internal capusule C. About 50% fibers cross to the opposite side to form the pyramidal decussation D. terminate in the anterior horns of gray matter of the spinal cord E. some fibers terminate in lateral horn of gray matter of the spinal cord 2. The trigeminal lemniscus ends in A.anterior thalamic nucleus B. medial thalamic nucleus C. anterior ventral nucleus D.posteromedial ventral nucleus E. posterolateral ventral nucleus Ⅱ. Multiple choice questions (two to five choices are correct, please circle the correct answers): 1. The tracts being related to transmitting sensory impulses in spinal cord are 59 A. fasciculus gracilis B. fasciculus cuneatus C. posterior spinocerebellar tract D. spinothalamic tract E. anterior corticospinal tract 2. The structures that conduct the fine touch sensation of the trunk and limbs are A. the medial leminiscus B. the lateral leminiscus C. the trigeminal leminiscus D. the spinal leminiscus E. the fasciculus gracilis and fasciculus cuneatus Ⅲ. Answer the following questions 1. Show the way of the pupillary reflexes ( express by "→" ) 2. Write the pain, temperature and simple touch pathway of the trunk and limbs (using the arrows). 3. Write out the conscious proprioceptive and fine touch pathway of trunk and limbs (using the arrows). The Meninges and Blood Vessels of Brain and Spinal Cord, and Cerebrospinal Fluid Learning Objectives You should: 脑和脊髓的被膜 掌握硬脊膜的形态特征、硬膜外隙的位置与内容。 了解脊髓蛛网膜、软脊膜的形态特点。掌握蛛网膜下隙的位置、内容及终池的位 置。 掌握硬脑膜的形态特点。掌握硬脑膜形成的特殊结构(大脑镰、小脑幕、鞍膈) 的位置。掌握硬脑膜窦的名称、位置。掌握海绵窦的位置、穿经海绵窦的结构及 海绵窦的交通。 60 了解脑蛛网膜和软脊膜的结构特点。掌握小脑延髓池的位置。了解其它蛛网膜下 池的位置。 了解颅内、外静脉的交通。 脊髓和脑的血管 掌握脑的动脉来源、颈内动脉和椎动脉的行程及其主要分支。大脑前、中、后动 脉的发起和分布。 掌握大脑动脉环的组成和位置。 了解大脑浅、深静脉的回流概况。 了解脊髓的动脉和静脉。 脑脊液及其循环 掌握脑脊液的产生部位和循环途径。 The spinal cord and brain are surrounded by three membranes, the meninges. Named from the outside inward they are the dura mater, arachnoid, and pia mater. Ⅰ. Dura mater Ⅰ) Spinal dura mater: tough and thick protective sheath of connective tissue 1. Characters ⑴Above, attached to circumference of foramen magnum ⑵ Below, becomes thinner at level of S2, invests filum terminale to attach at back of coccyx ⑶ On each side, continuous with external membrane of spinal nerves at intervertebral foramina 2. Epidural space ⑴ Position: lies between spinal dura mater and periosteum of vertebral canal ⑵ Contents: a quantity of loose connective tissue, fat, lymphatic vessels and vertebral venous plexus, the spinal nerves on each side pass through the epidural space which is applicable for block anesthesia 3. Subdural space: a potential space lies between spinal dura mater and spinal arachnoid 61 mater Ⅱ) Cerebral dural mater 1. Characters ⑴ A thick and dense inelastic membrane that composed of two layers, an inner or meningeal and outer or endosteal ⑵ It is in loose contact with calvaria, and most strongly adherent to base of skull 2. Four septa:meningeal layer of dura mater gives rise to four septa assist in restricting rotatory displacement of the brain ⑴ Cerebral falx: a sickle-shaped fold lying in midline between two cerebral hemispheres, with free inferior margin just above corpus callosum, attaches to frontal crest and crista galli anteriorly and join tentorium of cerebellum posteriorly ⑵ Tentorium of cerebellum: a crescent-shaped fold that lies between cerebellum and cerebrum; in front there is a gap, the tentorial incisure, for passage of midbrain ⑶ Cerebellar falx: a small, sickle-shapes fold that projects forward between two cerebellar hemispheres ⑷ Diaphragma sellae: a small circular fold that coves hypophyseal fossa, a small opening in its center allows passage of stalk of hypophysis 3. Sinuses of dura mater: situated between layers of dura mater, lined by endothelium, and their walls are devoid of muscular tissue, and contain no valves ⑴ Superior sagittal sinus: occupies upper border of cerebral falx ⑵ Inferior sagittal sinus: lies in free lower margin of cerebral falx ⑶ Straight sinus: occupies line of junction of cerebral falx with tentorium of cerebellum ⑷ Confluence of sinus: is dilated junction of superior sagittal sinus and straight sinus ⑸ Transverse sinus: situated in transverse sulcus ⑹ Sigmoid sinus: situated in sigmoid sulcus and is continuous with internal jugular vein at internal jugular foramen ⑺ Cavernous sinus 62 ①Position: lies on each side of sella turcica ②Relations of cavernous sinus: internal carotid artery and abducent nerve run through the sinus; oculomotor and trochlear nerves and ophthalmic and maxillary divisions of trigeminal nerve liein the lateral wall of the sinus, between the endothelium and dura ⑻ Superior and inferior petrosal sinuses: lie at superior and inferior of petrous temporal bone, each superior petrosal sinus drains cavernous sinus into transverse sinus, and each inferior petrosal sinus drains cavernous sinus into internal jugular vein The flowing of the blood in dural sinus superior sagittal sinus inferior sagittal sinus → straight sinus → confluence of sinus → transverse sinus →superior petrosal sinus cavernous sinus sigmoid sinus →inferior petrosal sinus internal jugular vein Ⅱ. Arachnoid mater Ⅰ) Characters: a delicate membrane enveloping brain and spinal cord and lying between pia mater internally and dura mater externally. It is attached to the underlying pia by numerous arachnoid trabeculae, creating a considerable cavity between the arachnoid and the pial layer. II) Spinal arachnoid mater: a thin, delicate, tubular membran loosely investing spinal cord; above, it is continuous with cerebral arachnoid mater III) Cerebral arachnoid mater 63 1. Characters: a delicate membrane covering brain loosely, passing over sulci and entering only cerebral longitudinal and transverse fissures 2. Arachnoid granulations: in certain areas the arachnoid projects into sinuses of dura mater to form arachnoid granulations which serve as sites where cerebrospinal fluid diffuses into bloodstream IV) Subarachnoid space 1. Position: lies between pia and arachnoid maters containing cerebrospinal fluid 2. Subarachnoid cisterns ⑴ Terminal cistern: the largest part of subarachnoid space extending from termination of spinal cord to level of S2, where it is occupied by nerves of cauda equina, so it is the best site for a lumbar puncture ⑵ Cerebellomedullary cistern: lies between cerebellum and medulla ⑶ Interpeduncular cistern: lies between two crus cerebri ⑷ Pontine cistern: lies in front of pons ⑸ Superior cistern: lies between the splenium of corpus callosum and cerebellum Ⅲ. Pia mater Ⅰ) Characters: a delicate vascular membrane that closely invests the brain and spinal cord covering gyri and descending into deepest sulci Ⅱ) Spinal pia mater 1. Denticulate ligament: consist of 21 pairs triangular ligaments extending from spinal cord on each side between anterior and posterior roots of spinal nerves to spinal dura mate; these ligaments help to fix position of spinal cord. 2. Filum terminale: an extension of pia beyond conus medullaris Ⅲ) Cerebral pia mater: closely invests brain surface, continues as a sheath around the small vessels entering the brain; in some areas the pia invaginates into ventricles to take part in the formation of choroids plexus, which secretes cerebrospinal fluid. Ⅳ. Circulation of cerebrospinal fluid (CSF) Ⅰ) Cerebrospinal fluid is a clear colorless fluid, which acts as a transport medium for nutrients and vaster products and provides a protective fluid cushion for the central nervous system. Ⅱ) Production: The CSF is produced by the choroids plexuses within the lateral, third and fourth ventricles. 64 Ⅲ) Circulation: CSF drains from lateral ventricle through interventricular foramina into third ventricle, then through mesencephalic aqueduct into fourth ventricle; fluid escapes from fourth ventricle through its openings, median and two lateral apertures of fourth ventricle , and enters the subarachnoid space; after circulating around brain and spinal cord, it is reabsorbed into dural venous sinuses, particularly superior sagittal sinus, through arachnoid granulations. interventricular foramina CSF drains from lateral ventricle third ventricle mesencephalic aqueduct median and two lateral apertures fourth ventricle arachnoid granulations subarachnoid space superior sagittal sinus vein Ⅴ. Blood vessels of brain and spinal cord Ⅰ) Arteries of brain 1. Two sources ⑴ Internal carotid artery: supplies anterior 2/3 of cerebral hemisphere and parts of diencephalon ⑵ Vertebral artery: supplies posterior 1/3 of cerebral hemisphere and parts of diencephalon, brain stem and cerebellum 2. Internal carotid artery ⑴ Course: arises from common carotid artery and passes upward through carotid canal to enter cranial cavity and passes cavernous sinus to the brain ⑵ branches: ① Anterior cerebral artery: runs forward and medially and enters longitudinal fissure of cerebrum. It is joined the fellow of the opposite side by the anterior communicating artery. It curves backward over the corpus callosum. a) Cortical branches: supply all medial surface of the cerebral cortex as far back as the parietooccipital sulcus and superior border of the suprolateral 65 surface of the cerebral hemisphere b) Central branches: supply caudate nucleus, anterior part of lentiform nucleus and anterior limb of internal capsule ② Middle cerebral artery: the largest branch of internal carotid artery, runs laterally in lateral sulcus a) Cortical branches: supply most of superolateral surface of cerebral hemisphere and insular lobe b) Central branches: supply lentiform and caudate nuclei, genu and posterior limb of internal capsule (lenticulostriate artery) ③ Anterior choroidal artery: passes backward, enters inferior horn of lateral ventricle, and ends in choroid plexus. It supplies lateral geniculate body, posterior limb of internal capsule, middle 3/5 of crus cerebri,and globus pallidus ④ Posterior communicating artery: runs backward to join posterior cerebral artery 2. Vertebral artery ⑴ Course: arises from subclavian artery and ascends through transverse foramina of sixth through first cervical vertebrae. It enters skull through foramen magnum and passes upward, forward, and medially on medulla oblongata. At lower border of pons it joints the vessel of the opposite side to form basilar artery. ⑵Cranial branches of vertebral artery includes: ① Anterior and posterior spinal arteries ② Posterior inferior cerebellar artery: supplies posterior part of cerebellum and postrolateral part of medulla ⑶Branches of basilar artery ① Anterior inferior cerebral artery ② Labyrinthine artery ③ Pontine arteries ④ Superior cerebellar artery 66 ⑤ Posterior cerebral artery: on each side curves laterally and backward around midbrain a) Cortical branches: supply medial and inferior surfaces of temporal lobe and occipital lobe b) Central branches: supply dorsal thalamus, medial and lateral geniculate bodies, hypothalamus and subthalamus 3. Cerebral arterial circle ( circle of Willis ) ⑴ Formation: formed by anterior communicating artery, both anterior cerebral arteries, internal carotid arteries, posterior communicating arteries, and posterior cerebral arteries ⑵ Position: lies on sella turcica around optic chiasma, tuber cinereum and mamillary bodies This is an anastomosis between branches of the internal carotid arteries and the vertebral arteries. It allows blood entering either the carotid or vertebral artery to flow to any part of both cerebral hemispheres. Ⅱ) Veins of brain 1. Superficial cerebral veins: drain blood from cortex and subcortical medullary substance and empty into adjacent sinuses of dura mater 2. Deep cerebral veins: drain deeper parts of hemispheres, basal nuclei, internal capsule, diencephalon and choroid plexus, ultimately form great cerebral vein which enter straight sinus Ⅲ) Blood vessels of spinal cord 1. Arteries of spinal cord 67 ⑴ Two sources ① Anterior and posterior spinal arteries ② Branches of segmental arteries: radicular arteries of posterior intercostals arteries, lumbar arteries, and lateral sacral arteries ⑵ Damage area: T1~T4, ventral part of L1 ⑶ The spinal cord is surrounded by a vascular ring ( vasocorona ), from which vessels extend into the white matter. The anterior spinal artery supplies the anterior horn, the base of posterior horns and the great part of anterolateral funiculus. The posterior spinal arteries supply the posterior funiculus and the remainder of the posterior horns. The marginal zone of anterolateral funiculus is supplied by plexus of the vasocorona. 2. Spinal veins: have a general distribution similar to that of spinal artery, and drain into internal vertebral venous plexus Sdudy questions Ⅰ. Single choice questions (there five choices on each question, only one is correct, please circle the correct answer): 1. The blood supply of motor speech area comes from A. anterior cerebral artery B. middle cerebral artery C. posterior cerbral artery D. vertebral artery E. basilar artery 2. Subarachnoid space A. lies between arachnoid and pia maters B. lies between arachnoid and dura maters C. lies between dura and pia maters D. lies between spinal dura mater and periosteum of vertebral canal E. contains a quantity of loose connective tissue, fat, lymphatic vessels and vertebral venous plexus, Ⅱ. Multiple choice questions (two to five choices are correct, please circle the correct answers): 1. The epidual space A. is filled with cerebrospinal fluid. 68 B. is between the spinal dura matter and the periosteum of the vertebral canal. C. is not open into the cranial cavity. D. contains loose areolar tissue,venous plexus, lymphatic and roots of spinal nerve E. all above are incorrect. 2. The cerebral arterial circle is formed by A. the anterior cerebral a. B. the middle cerebral a. C. the posterior cerebral a. D. the anterior communicating a. E. the posterior communicating a. Ⅲ. Answer the following questions 1. Describe the position and formation of cerebral arterial circle. 2. Write out the producting place and the circulation of cerebrosprinal fluid (to express in “→” ). 3. Write out the names of dural sinus, and the flowing of the blood in them ( the direction can be used by "→" ). Part ⅢThe Peripheral Nervous System The Spinal Nerves Learning Objectives You should: 掌握脊神经的构成、区分、纤维成份、分支及分布概况。 掌握颈丛的组成、位置。了解颈丛皮支的名称、浅出部位及分布。掌握膈神经的组成 及在颈部的行径。 掌握臂丛的组成、位置、分支。掌握肌皮神经、正中神经、尺神经、桡神经、腋神经 的分支和分布。了解其行径及损伤后的主要表现。了解胸长神经、胸背神经的分布。] 掌握胸神经前支的分布概况及其皮支的分布特点。 掌握腰丛的组成、位置、主要分支及分布。掌握股神经、闭孔神经的行径、分支和分 69 布。 掌握骶丛的组成、位置及主要分支。掌握坐骨神经的行径、分支及分布。了解腓总神 经、腓深神经、腓浅神经和胫神经的行径,掌握腓深神经、腓浅神经和胫神经的分布。 了解损伤后的临床表现。 Ⅰ. General description There are 31 pairs spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal nerve. Ⅰ) Formation: each spinal nerve is formed by union of anterior and posterior roots at intervertebral foramen 1. The anterior root contains motor fibers for skeletal muscles. Those from T1 to L2 contain sympathetic fibers; S2 to S4 also contain parasympathetic fibers. 2. The posterior root contains sensory fibers whose cell bodies are in the spinal ganglion. Ⅱ) Functional components 1. Somatic efferent nerve fibers (SE): fibers that transmit motor impulses from spinal cord to skeletal muscles. 2. Visceral efferent nerve fibers (VE): fibers that transmit motor impulses from spinal cord to smooth muscles, cardiac muscle and glands. 3. Somatic afferent nerve fibers (SA): fibers that transmit exteroceptive and proprioceptive impulses from body to spinal cord 4. Visceral afferent nerve fibers (VA): fibers that transmit interoceptive impulses from the viscera to spinal cord Ⅲ) branches of spinal nerves 1. Anterior branch: largest , innervates anterolateral body wall and limbs,the great nerve plexus, e.g. the cervical, brachial, lumbar, and sacral, are formed by anterior rami 2. Posterior branch: innervates the back of the trunk 3. Communicating branch: connect the spinal nerve to the sympathetic trunk 4. Meningeal branch: re-enters vertebral canal through intervertebral foramen to dura mater Ⅱ. Cervical plexus 70 Ⅰ) Formation: formed by anterior rami of C1-C4 spinal nerves Ⅱ) Position: lies in front of the origin of levator scapulae and scalenus medius and deep to the superior part of the sternocleidomastoid Ⅲ) Branches 1. Cutaneous branches: emerge around middle of posterior border of sternocleidomastoid, to supply skin of neck and scalp between auricle and external occipital protuberance Nerve Course and ditribution Lesser occipital Ascends along posterior border of the sternocleidomastoid, to supply skin behind auricle Greet auricular Ascends across sternocleiodomastoid in company with eternal jugular vein to supply skin cover angle of mandible, parotid gland and mastoid process and on both surface of auricle Transverse nerve of neck Passes forward across sternocleidomastoid to supply skin in anterior surface of neck Supraclavicular Pass downwards over clavicle and supply skin down as far as second intercostals space 2. Muscular branches: supply the deep muscles of neck 3. Phrenic nerve (anterior rami of C3-C5) to diaphragm (motor and sensory): (1) Descends over scalenus anterior to enter thorax (2) Accompanied by pericardiophrenic vessels and passes anterior to lung roots between mediastinal pleura and pericardium to supply motor and sensory innervation to diaphragm (3) Sensory fibers supply to pleurae, pericardium and peritoneum of diaphragm; usually right phrenic nerve may be distributed on live, gallbladder and biliary system. 4. Ansa cervicalis: hypoglossal nerve gives off superior root of ansa (descendens 71 hypoglossi), composed of fibers picked up from nerve C1; it joins inferior root of ansa (descendens cervicalis, C2and C3) to form a loop, the ansa cervicalis, which supplies infrahyoid muscles III. Brachial plexus I) Formation: formed by anterior rami of C5-C8 and T1 spinal nerves II) Position: passes through the scalene fissure to posterosuperior of subclavian artery, then enters the axilla to form three cords III) Main branche musculocutaneous n. → lateral antebrachial cutaneous n. Lateral cord lateral root anterior interosseous n. median n. medial root Medial cord recurrent n. common palmar digital n. ulnar n. medial brachial and medial antebrachial cutaneous n. radial n. → superficial and deep branches Posterior cord axillary n. thoracodorsal n. → latissimus dorsi Long thoracic n. → serratus anterior Nerve Distribution Injury Musculocutaneous Biceps brachii, brachalis and coracobrachialis ‘BBC nerve’; skin on anterior aspect of forearm Median Flexor of forearm except brachioradialis, flexor carpi Apehand ulnaris and ulnar half of flexor digitorum profundus, thenar except adductor pollicis, first two lumbricals; skin of thenar, central part of palm, palmar aspect of radial three and one-half fingers, including middle and distal fingers on dorsum Ulnar Flexor carpi ulnaris, ulnar half of flexor digitorum 72 clawhand profundus, hypothenar muscles, interossei, 3rd and 4th lumbricals and adductor pollicis; skin of hypothenar, palmar surface of ulnar one and one-half fingers, ulnar half of dorsum of hand, posterior aspect of ulnar two and one-half fingers Radial Extensor muscles of arm and forearm, brachioradialis; Wristdrop skin on back of arm, forearm, and radial side of dorsum of hand and radial two and one-half fingers Axillary Deltoid and teres minor muscle; skin over deltoid and upper posterior aspect of arm IV. Anterior branches of thoracic nerves I) Intercostal nerves (anterior rami of T1- T11): runs forward inferiorly to intercostals vessels in costal groove of corresponding rib, between intercostals externi and intercostals interni; first six nerves are distributed within their intercostals space, lower five intercostals nerves leave anterior ends of their intercostals spaces to enter abdominal wall II) Subcostal nerve (anterior ramus of T12): follows inferior border of T12 rib and passes into abdominal wall III) Distribution: distributed to intercostales and anterolateral abdominal muscles, skin of thoracic and abdominal wall, parietal pleura and peritoneum ★ The segmental innervation of anterior surface of trunk Segment Supply the level T2 Sternal angle T4 Nipple T6 Xiphoid process T8 Costal arch T10 Umbilicus T12 Midpoint between umbilicus and symphysis pubis 73 V. Lumbar plexus I) Formation: formed by anterior rami of L1-L3, a part of anterior rami of T12and L4 II) Position: lies within substance of psoas major III) Branches Nerve Course and distribution Iliohypogastric Supplies lower part of anterior abdominal wall Ilioinguinal Passes through inguinal canal to supply skin of the groin and scrotum Lateral femoral cutaneous Femoral Passes deep to inguinal ligament, 2-3cm medial to anterior superior iliac spine; supplies skin on anterior and lateral aspects of thigh Runs downward and laterally between psoas and iliacus, passes deep to inguinal ligament; supplies anterior thigh muscles (quadriceps, sartorius and pectineus), hip and knee joint, and skin on anteromedial side of thigh, saphenous nerve is distributed to skin of medial side of leg and foot Obturator Enters thigh through obturator foramen; supplies medial group of muscles of thigh, obturator externus, and skin of medial side of thigh Genitofemoral Descends on anterior surface of psoas major and divides into genital and femoral branches; femoral branch supplies skin over femoral triangle; genital branch supplies scrotum or greater lip pudendum VI. Sacral plexus I) Formation: formed by anterior rami of L4 and L5 spinal nerves (the lumbrosacral trunk) and anterior rami of sacral and coccygeal nerves II) position: lies in pelvic cavity, anterior to sacrum and piriformis III) Branches 74 Nerve Course and distribution Superior Leaves pelvis through suprapiriform foramen and passes between gluteus gluteal Inferior medius and minimus to supplies these muscles and tensor fasciae latae Leaves pelvis through infrapiriform foramen; and supplies gluteus maximus gluteal Pudendal Leaves pelvis through infrapiniform foramen, crosses ischial spine with internal pudendal artery and immediately reenter perineum through lesser sciatic foramen, then passes forward in pudendal canal by means of it branches supplies external anal sphincter and the muscles and skin of the perineum; main branches are anal nerve, perineal nerve, dorsal nerve of penis (clitoris) Posterior Leaves pelvis through infrapiniform foramen, runs deep to gluteus maximus femoral and emerges from its inferior border to supply skin of buttock and then cutaneou surface skin over posterior of thigh and calf Sciatic Leaves pelvis through infrapiriform foramen to enter gluteal region, runs inferiorly laterally deep to gluteus maximus, passing midway between the greater trochanter of femur and ischial tuberosity to back of thigh, lying deep to long head of biceps femoris, normally divided into tibial and common peroneal nerves just above popliteal fossa; innervates semitendinosus, semimembranosus and biceps femoris and has articular branches to hip and knee joints Common peroneal Arises at apex of popliteal fossa and follows medial border of biceps femoris and its tendon; passes over posterior aspect of head of fibula and then winds around neck of fibula, deep to peroneus longus, where it divides intodeep and superficial peroneal nerves; supplies skin on posterolateral part of leg via its branch—lateral sural cutaneous nerve Deep peroneal Arises between peroneus longus and neck of fibula; descends on interosseous membrane and enters dorsum of foot; supplies anterior muscles of leg, and skin of first interdigital cleft Superficial peroneal Arises between peroneus longus and neck of fibula and descends in lateral compartment of leg; supplies peroneus longus and brevis and skin on anterior surface of leg and dorsum of foot Tibial Decends through popliteal fossa and lies on popliteus; then runs inferiorly with posterior tibial vessels and terminates beneath flexor retinaculum by dividing 75 into medial and lateral plantar nerves; supplies posterior muscles of leg and knee joint Sdudy questions Ⅰ. Single choice questions (there five choices on each question, only one is correct, please circle the correct answer): 1.Which is false about sacral plexus A. It is formed by anterior branches from the part of 4th lumbar nerve to coccygeal nerve B. It lies anterior to the sacrum and piriformis in the pelvic cavity C. It gives out posterior femoral cutaneous nerve to posterior surface skin of thigh D. It gives out sciatic nerve to innervate the all muscles of thigh E. It gives out inferior gluteal nerve to innervatethe gluteus maximus 2.If the plantar flexion at ankle joint is not permitted, which nerve may be damaged? A. deep peroneal nerve B. superficial peroneal nerve C. tibial nerve D. obturator nerve E. femoral nerve Ⅱ. Multiple choice questions (two to five choices are correct, please circle the correct answers): 1.Which nerves distribute to the skin of hand A. radial nerve B. axillary nerve C. musculocutaneus nerve D. ulnar nerve E. median nerve 2.Which nerves arise from the lumbar plexus A. femoral nerve B. sciatic nerve C. obturator nerve D. ilioinguinal nerve E. lateral femoral cutaneous nerve Ⅲ. Answer the following questions 76 1.Describe the origin, course, branches and distribution ( muscle groups ) of the sciatic nerve. 2.Describe the origin, course and distribution of the phrenic nerve. 3.Describe the origin and distribution of the median, ulnar and radial nerves. The Cranial Nerves Learning Objectives You should: 掌握脑神经的名称、性质、连脑部位、进出颅的部位。 了解嗅神经的功能性质和分布。 掌握视神经的功能性质、行程及被膜。 掌握动眼神经的纤维成份、行程及分布。了解睫状神经节的位置与性质。 掌握滑车神经的分布。 掌握三叉神经的纤维成份、主要分支和分布概况;三叉神经节的位置与性质。 掌握展神经的分布。 77 掌握面神经的纤维成份、主要分支的分布概况。了解翼腭神经节和下颌下神经节的位 置与性质。 掌握前庭蜗神经的功能性质。 掌握舌咽神经的纤维成份、主要分支的分布概况。了解耳神经节的位置与性质。 掌握迷走神经的纤维成份、主干行程、主要分支及分布概况。 掌握副神经和舌下神经的分布概况。 Ⅰ. Names of cranial nerves There are twelve pairs of cranial nerves which leave the brain and pass through foramina in the skull. The cranial nerves named from 1 to 12 according to the anterior to posterior order in which they emerge from the brain. Cranial nerves have been given both names and numbers, and Roman numbers should be used. The cranial nerves are as follows: ⅠOlfactory nerve ⅦFacial nerve ⅡOptic nerve ⅧVestibulocochlear nerve ⅢOculomotor nerve ⅨGlossopharyngeal nerve ⅣTrochlear nerve ⅩVagus nerve ⅤTrigeminal nerve ⅪAccessory nerve ⅥAbducent nerve ⅫHypoglossal nerve Ⅱ. Functional components 1. General somatic afferent fibers (GSA): transmit exteroceptive and proprioceptive impulses from head and face to somatic sensory nuclei 2. Special somatic afferent fibers (SSA): transmit sensory impulses from special sense organs of vision, equilibrium and hearing to the brain 3. General visceral afferent fibers (GVA): transmit interoceptive impulses from the viscera to the visceral sensory nuclei 4. Special visceral afferent fibers (SVA): transmit sensory impulses from special sense organs of smell and taste to the brain 5. General somatic efferent fibers (GSE): innervate skeletal muscles of eye and tongue 6. General visceral efferent fibers (GVE): transmit motor impulses from the general visceral motor nuclei and relayed in parasympathetic ganglions. The postganglionic 78 fibers supply cardiac muscles,smooth muscles and glands 7. Special visceral efferent fibers (SVE): transmit motor impulses from the brain to skeletal muscles derived from brachial (gill) arches of embryo. These include the muscles of mastication, facial expression and swallowing. According to the components and functions the 12 pairs of cranial nerves are divided into three types: ①some cranial nerves contain only afferent (sensory) fibers and thus are called sensory cranial nerves. ②some cranial nerves contain only efferent (motor) fibers and thus are called motor cranial nerves. ③the remainder contain both sensory and motor fibers and are referred to as mixed nerves. Ⅲ. Sensory cranial nerves Nerve Ⅰ Location of cell body Cranial and axon categories exit Olfactory cells (SVA) Cribriform Terminal nuclei Main action Olfactory bulb Smell Lateral geniculate Vision foramina Ⅱ Ganglion cells (SSA) Optic canal body Ⅷ Vestibular ganglion(SSA) Internal Cochlear ganglion (SSA) acoustic Vestibular nuclei Equilibrium Cochlear nuclei Hearing meatus Ⅳ. Motor cranial nerves Nerve Nucleus of origin and Cranial exit Main action Superior orbital Motor to superior, inferior and medial fissure recti; inferior obliquus; levator axon categories Ⅲ Nucleus of oculomotor (GSE) palpebrae superioris; raises upper eyelid;tuns eyeball superiorly,inferiorly, and medially Accessory nucleus of Parasympathetic innervation oculomotor (GVE) sphincter pupillea and ciliary muscle; constricts pupil and accommodates lens of eye 79 Ⅳ Ⅵ Ⅺ Nucleus of trochlear Superior orbital nerve (GSE) fissure Nucleus of abducent Superior orbital nerve (GSE) fissure Nucleus of accessory Jugular foramen Motor to superior obliquus Motor to lateral rectus Motor to sternocleidomastoid and nerve (SVE) Ⅻ Nucleus of hypoglossal trapezius Hypoglossal canal Moror to muscles of tongue nerve( GSE) Ciliary ganglion: lies between optic nerve and lateral rectus Ⅲ. Mixed cranial nerves A. Trigeminal nerve (Ⅴ) 1. Components of fibers a) SVE fibers: originate from motor nucleus of trigeminal nerve, and supply masticatory muscles b) GSA fibers: transmit facial sensation to sensory nuclei of trigeminal nerve, the GSA fibers have their cell bodies in trigeminal ganglion, which lies on the apex of petrous part of temporal bone 80 2. Branches: There are three divisions, each of which has several branches. a) Ophthalmic nerve (Ⅴ1, sensory) ⑴Leave the skull through the superior orbital fissure, to enter orbital cavity ⑵Branches ① Frontal nerve: divides into supratrochlear nerve and supraorbital nerve ② Lacrimal nerve ③ Nasociliary nerve ⑶Distribution: sensation from cerebral dura mater, visual organ, mucosa of nose, skin above the eye and back of nose b) Maxillary nerve (Ⅴ2, sensory) ⑴ Leave skull through foramen rotundum, crosses pterygopalatine fossa, passes through inferior orbital fissure to enter orbital cavity, the nerve is now called infraorbital nerve, and it runs forward on floor of orbit, fist in infraorbital groove and then in infraorbital canal, and emerges through infraorbital foramen ⑵Branches ①Infraorbital nerve ②Zygomatic nerve ③Superior alveolar nerve ④Pterygopalatine nerve ⑶ Distribution: sensation from cerebral dura mater, maxillary teeth , mucosa of nose and mouth, skin between eye and mouth c) Mandibular nerve (Ⅴ3, mixed) ⑴Leave the skull through the foramen ovale to enter the infratemporal fossa ⑵Branches ①Auriculotemporal nerve ②Buccal nerve ③Lingual nerve ④ Inferior alveolar nerve: pass though the mandibular foramen to enter mandibular canal, and emerges through mental foramen, the nerve is now called mental nerve ⑤Nerve of masticatory muscles ⑶ Distribution: sensation from cerebral dura mater, teeth and gum of lower jaw, mucosa of floor of 81 mouth and anterior 2/3 of tongue, skin of auricular and temporal regions and below the mouth; motor to masticatory muscles, mylohyoid, and anterior belly of digastric B. Facial nerve (Ⅶ) 1. Components of fibers a) SVE fibers originate from nucleus of facial nerve, and supply facial muscles b) GVE fibers derived from superior salivatory nucleus and relayed in pterygopalatine ganglion and submandibular ganglion. The postganglionic fibers supply lacrimal, submandibular and sublingual glands c) SVA fiber from taste buds of anterior two-thirds of tongue which cell bodies are in the geniculate ganglion of the facial nerve and end by synapsing with cells of nucleus of solitary tract d) GSA fibers from skin of external ear 2. Course: leaves skull through internal acoustic meatus, facial canal and stylomastoid foramen, it then enters parotid gland where it divides into five branches which supply facial muscles 3. Branches within the facial canal a) Chorda tympani: joins lingual branch of mandibular nerve ⑴to taste buds on anterior two-thirds of tongue ⑵ relayed in submandibular ganglion, the postganglionic fibers supply submandibular and sublingual glands b) Greater petrosal nerve: GVE fibers pass to pterygopalatine ganglion and there relayed through the zygomatic and lacrimal nerves to lacrimal gland c) stapedial nerve: to stapedius 4. Branches outside of facial canal: facial nerve enters parotid gland and divides into its five terminal branches for muscles of expression a) Temporal b) Zygomatic c) Buccal d) Marginal mandibular e) Cervical 82 facial 5. Pterygopalatine ganglion: lies in pterygopalatine fossa under maxillary nerve 6. submandibular ganglion: lies between lingual nerve and submandibular gland C. Glossopharyngeal nerve (Ⅸ) 1. Components of fibers a) SVE fibers: originate from nucleus ambiguus, and supply stylopharygeus b) GVE fibers: arise from inferior salivatory nucleus and ralyed in otic ganglion, the postganglionic fibers supply parotid gland c) SVA fibers: arise from the cells of inferior ganglion, the central processes of these cells terminate in nucleus of solitary tract, the peripheral processes supply the taste buds on posterior third of tongue d) GVA fibers: visceral sensation from mucosa of posterior third of tongue, pharynx, auditory tube and tympanic cavity, carotid sinus and glomus, and end by synapsing with cells of nucleus of solitary tract e) GSA fibers: sensation from skin of posterior surface of auricle 2. Course: leaves the skull via jugular foramen 3. Branches a) Lingual branches: to taste buds and mucosa of posterior third of tongue b) Pharyngeal branches: take part in forming the pharyngeal plexus c) Tympanic nerve: GVE fibers via tympanic and lesser petrosal nerves to otic ganglion, with postganglionic fibers via auriculotemporal (Ⅴ3) to parotid gland d) Carotid sinus branch: innervations to both carotid sinus and glomus e) Others: tonsillar and stylophayngeal branches f) Otic ganglion: situated just below foramen ovale D. Vagus nerve (Ⅹ) 1. components of fibers a) GVE fibers: originate from dorsal nucleus of vagus nerve, synapse in parasympathetic ganglion, short postganglionic fibers innervate cardiac muscles, smooth muscles and glands of viscera b) SVE fibers: originate from ambiguus, to muscles of pharynx and larynx c) GVA fibers: carry impulse from viscera in neck, thoracic and abdominal cavity to nucleus of solitary tract 83 d) GSA fiber: sensation from auricle, external acoustic meatus and cerebral dura mater 2. Course: a) Exits the skull from jugular foramen b) Descends in the neck in carotid sheath between internal (or common) carotid artery and internal jugular vein c) Right vagus nerve ⑴ Enter thoracic inlet on right side of trachea ⑵ Travels downward posterior to right brachiocephalic vein and superior vena cava ⑶ Passes posterior to right lung root ⑷ Forms posterior esophageal plexus ⑸ Forms posterior vagal trunk at esophageal hiatus where it leaves thorax and passes into abdominal cavity, then divides into posterior gastric and celiac branches d) Left vagus nerve ⑴ Enter thoracic inlet between left common carotid and left subclavian arteries, posterior to left brachiocephalic vein ⑵Crosses aortic arch where left recurrent laryngeal nerve branches off ⑶ Passes posterior to left lung root ⑷ Forms anterior esophageal plexus ⑸ Forms anterior vagal trunk at esophageal hiatus where it leaves thorax and passes into abdominal cavity , then divides into anterior gastric and hepatic branches 3. Branches in neck a) Superior laryngeal nerve: passes down side of pharynx and given rise to ⑴ Internal branch, which pierces thyrohyoid membrane to innervates mucous membrane of larynx above fissure of glottis ⑵ External branch, which innervates cricothyroid b) Cervical cardiac branches : descending to terminate in cardiac plexus c) Others: auricular, pharyngeal and meningeal branches 84 4. Branches in thorax a) Recurrent laryngeal nerves ⑴ Right one hooks around right subclavian artery, left one hooks aortic arch ⑵Both ascend in tracheo-esophageal groove ⑶ Nerves enter larynx posterior to cricothyroid joint, the nerve is now called inferior laryngeal nerve ⑷ Innervations: laryngeal mucosa below fissure of glottis , all laryngeal laryngeal muscles except cricothyroid b) Bronchial and esophageal branches 5. Branches in abdomen a) Anterior and posterior gastric branches ⑴ Run close to lesser curvature and innervate anterior and posterior surfaces of stomach ⑵ As far as pyloric antrum to fan out into branches in a way like the digits of a crow’s foot to supply pyloric part b) Hepatic branches: join hepatic plexus and then supply liver and gallbladder c) Celiac branches: send branches to celiac plexus to be distributed with sympathetic fibers to liver, pancreas, spleen, kidneys, intestine as far as left colic flexure Sdudy questions Ⅰ. Single choice questions (there five choices on each question, only one is correct, please circle the correct answer): 1. The nerves passing through the jugular foramen A. glossopharyngeal nerve, facial nerve and vagus nerve B. glossopharyngeal nerve, acessory nerve and vagus nerve C. glossopharyngeal nerve, hypoglossal nerve and vagus nerve D. glossopharyngeal nerve, hypoglossal nerve and acessory nerve E. glossopharyngeal nerve, hypoglossal nerve and vestibulocochlear nerve 2. The facial nerve A. general visceral efferent fibers originate from inferior salivatory nucleus 85 B. emerges from the bulbopontine sulcus C. leave the skull through the foramen rutundum D. supplies the skin of the face E. supplies parotid gland Ⅱ. Multiple choice questions (two to five choices are correct, please circle the correct answers): 1. General visceral efferent fibers of the facial nerve supply A. parotid fland B. lacrimal gland C. sublingual gland D. thyroid gland E. submandibular gland 2.The vagus nerves A. are visceral motor nevers B. contain the preganglionic fibers of parasympathic nerve C. attached to the medulla oblongata D.form anterior and posterior vagual trunk at esophageal hiatus where they leave the thorax and pass into the abdominal cavity E. supply all of visceral organs in the thoracic, abdominal and pelvic cavities Ⅲ. Answer the following questions 1. Write out the nerves which distribute the tongue and their functions. 2. Write out the nerves which distribute the muscles which move the eyeball and coordinate the pupil. 3. Write the fiber components, respective origins and distribution of the oculomotor nerve The Visceral Nervous System Learning Objectives You should: 掌握内脏神经的区分和分布。 内脏运动神经::掌握内脏运动神经与躯体运动神经的主要区别。掌握节前神经元、节 前纤维、节后神经元节及后纤维的概念。 交感神经 掌握交感神经的低级中枢部位。掌握交感干的位置与组成、主要椎前节的位 置。 了解灰、白交通支的概念、节前纤维和节后纤维的走行规律。 了解交感神经的分布概况。 86 颈部:了解颈上、中、下神经节的位置及节后纤维的分布概况。 胸部:掌握内脏大神经、内脏小神经的起源、纤维联系及分布概况。 腰部:掌握腰内脏神经的起源、纤维联系。了解节后纤维的分布概况。 盆部:了解节后纤维的分布概况。 副交感神经 掌握副交感神经的低级中枢部位。 掌握动眼神经内副交感节前纤维的起始、交换神经元的部位和节后纤维的分 布概况。 掌握面神经、舌咽神经内副交感节前纤维的起始、交换神经元的部位和节后 纤维的分布概况。 掌握迷走神经内副交感节前纤维的起始与节后纤维的分布概况。 掌握盆内脏神经的分布概况。 掌握交感神经与副交感神经的主要区别。了解内脏神经对器官双重支配的概念。 了解主要内脏神经丛的位置及分布。 内脏感觉神经:了解内脏感觉神经传入途径及特点。了解牵涉痛的概念。 sympathetic part Visceral motor nerves Composition (autonomic nervous system) parasympathetic part Visceral sensory nerves Ⅰ. Visceral motor nerves 87 Main differences between somatic motor and visceral motor nerves Somatic Visceral Effectors Skeletal muscles Cardiac, smooth muscles and glands Kind of fibers One Two: sympathetic and parasympathetic From lower center Single neuron Two neurons: preganglionic neuron (fiber) to effect require Fibers and postganglionic neuron (fiber) Thick myelinated Preganglionic: thin myelinated postganglionic: unmyelinated Distributive form Nerve trunk Nerve plexuses Control Voluntary Involuntary (unconsciousness ) (consciousness) A. Sympathetic part 1. Lower center: located in lateral gray horn of spinal cord segments T1~L3 2. Sympathetic ganglia a) Paravertebral ganglia: arranged on either side of vertebral column, consist of 19~22 of oval-shaped ganglia : ⑴Three cervical: ①Superior cervical ganglion: largest, situated in front of transverse processes of C1~C3 vertebra ② Middle cervical ganglion: smallest, is at level of transverse processes of C6 vertebra ③Inferior cervical ganglion: situated at level of C7 vertebra, and may be fused with first thoracic ganglion to form cervicothoracic ganglion ⑵10~12 thoracic ⑶4 lumbar ⑷2~3 sacral ⑸Ganglion impar: unpaired on the anterior face of coccyx 88 ☆ Sympathetic trunk: formed by paravertebral ganglia and interganglionic branches, lie on either side of vertebral column from base of skull to coccyx. The trunks of two side unite in front of the coccyx at a small swelling, the ganglion impar b) Prevertebral ganglia: lie anterior to vertebral column and near the arteries for which they are named ⑴Celiac ganglion ⑵Aorticorenal ganglion ⑶Superior mesenteric ganglion ⑷Inferior mesenteric ganglion 3. Three fates of preganglionic fibers Preganglionic fibers emerge from spinal cord with motor roots of corresponding spinal nerves. They leave the spinal nerves by way of the white communicating branch and enter the sympathetic trunks. Only the ganglia of T1 to L3 receive white communicating branches, the white communicating branches have 15 pairs, lightly mylinated axons. 15 pairs white communicating branch preganglionic fibers sympathetic trunk (only spinal levels T1~L3 have white communicating branch) a) Relay in corresponding ganglion b) Ascend or descend in sympathetic trunk and relay in higher or lower ganglia c) Pass without synapse to a prevertebral ganglion for relay ⑴Greater and lesser splanchnic nerves The greater splanchnic nerve formed by preganglionic fibers from T5~T9 ganglia, and relay in celiac ganglion. The lesser splanchnic nerve formed by preganglionic fibers from T10~T12 ganglia, and relay in aorticorenal ganglion. The postganglionic fibers supply the liver, spleen, kidney and alimentary tract as far as the left colic flexure. greater splanchnic n. 〈○ preganglionic fibers from T5~T9 ganglia celiac ganglion lesser splanchnic n. 〈○ preganglionic fibers from T5~T9 ganglia 89 aorticorenal ganglio liver, spleen, kidney and alimentary tract as far as the left colic flexure ⑵Lumbar splanchnic nerve lumbar splanchnic nerve 〈○ preganglionic fibers from L1~L4 ganglia prevertebral ganglia descending and sigmoid colon, rectum, pelvic viscera and lower limbs 4. Three fates of postganglionic fibers a) Back to a spinal nerve along gray communicating branches ( 31 pairs ) to terminate in blood vessels, arrectores pilorum and sweat glands of head, neck, trunk and limbs b) The fibers from their networks around blood vessels passing to visceral end organs c) Terminate directly in certain organs Distribution of sympathetic nerve Preganglionic fibers Postganglionic fibers T1~T5 Head, neck, upper limb and thoracic viscera T5~T12 Abdominal viscera L1~L3 Pelvic viscera and lower limb A. Parasympathetic part 1. Lower center: located in four pairs parasympathetic nuclei in brain stem and in sacral parasympathetic nucleus of spinal cord segments S2~S4 2. Parasympathetic ganglia: terminal ganglia are near or within the wall of a visceral organ ( para-organ ganglia or intramural ganglia ) 3. Cranial outflow (portion) a) Accessory nucleus of oculomotor nerve: preganglionic fibers from accessory nucleus of oculomotor nerve travel by way of the oculomotor nerve to the ciliary ganglion, postganglionic fibers from ciliary ganglion terminate in sphincter pupillae and ciliary muscles of eye 90 Ⅲ accessory oculomotor nucleus○ sphincter pupillae and ciliary muscles 〈○ ciliary ganglion b) Superior salivatory nucleus pterygopalatine ganglion Ⅶ lacrimal gland 〈○ superior salivatory nucleus○ submandibular gland 〈○ submandibular ganglion sublingual gland c) Inferior salivatory nucleus Ⅸ inferior salivator nucleus○ parotid gland 〈○ otic ganglion d) Dorsal nucleus of vagus nerve Ⅹ dorsal nucleus of vagus n. ○ heart, lungs, liver, spleen, kidneys,alimentary tract 〈○ terminal ganglia as far as left colic flexure 4. Sacral outflow (portion) Preganglionic fibers from sacral parasympathetic nucleus leave spinal cord with anterior roots of the spinal nerves S2~S4, then leave sacral nerves and form pelvic splanchnic nerve and travel by way of sacral plexus to terminal ganglia in pelvic cavity, postganglionic fibers terminate in descending and sigmoid colon, rectum and pelvic viscera anterior roots of S2~S4 sacral nerves sacral parasympathetic nucleus ○ pelvic plexus 91 pelvic splanchnic nerve descending and sigmoid colon, rectum and pelvic viscera 〈○ terminal ganglia B. Main differences between sympathetic and parasympathetic Lower center Sympathetic Parasympathetic Lateral gray horn of spinal Four pairs parasympathetic cord segments T1~L3 nuclei and sacral parasympathetic nucleus Ganglia Paravertebral, prevertebral Terminal Preganglionic f. Shorter Longer Postganglionic f. Longer Shorter Pre: Postganglionic 1: many more 1: a few Distributions Throughout the body Limited primarily to head and viscera of thorax, abdomen, and pelvis Different action Prepares for emergency Conserve and restore body situation (fight or flight) energy (rest and relaxation) C. Visceral plexuses 1. Cardiac plexuses: formed by sympathetic and parasympathetic components a) Superficial , below aortic arch b) Deep, anterior to bifurcation on trachea 2. Pulmonary plexus: anterior and posterior to lung roots 3. Celiac plexus: around roots of celiac trunk and superior mesenteric arteries 4. Abdominal aortic plexus: is caudalward continuation of celiac plexus 5. Hypogastric plexus: a) Superior hypogastric plexus: lies in front of L5 between common iliac ateries b) Inferior hypogastric plexus (pelvic plexus): lie on each side of rectum 92 Ⅱ.Visceral sensory nerves Ⅱ.Visceral sensory nerves Ⅸ, Ⅹ nucleus of solitary tract thalamus 〈○ cranial ganglia 〈○ enteroceptors of viscera cerebral cortex hypothalamus sympathetic nerve 〈○ pelvic splanchnic nerve somatic motor neurons 〈○ spinal ganglia posterior horn effector (reflex) visceral motor neuclei III. Referred pain Sdudy questions Ⅰ. Single choice questions (there five choices on each question, only one is correct, please circle the correct answer): 1.The lower center of the sympathetic nerve is located in A. gray matter in sacral segments S2~S4 of spinal cord B. the Diencephalon C. the cerebral cortex D. lateral horn of gray matter in segments T1~L3 of spinal cord E. the brain stem 2.Which structure is formed by preganglionic fibers of parasympathetic nerve A. lumbar splanchnic nerve B. pelvic splanchnic nerve C. gray communicating branches D. white communicating branches 93 E. lesser splanchnic nerve Ⅱ. Multiple choice questions (two to five choices are correct, please circle the correct answers): 1.which ganglia belong to the sympathetic ganglia A. superior cervical ganglion B. inferior cervical ganglion C. paravertebral ganglia D. prevertebral ganglia E. geniculate ganglion 2.The lower center of the parasympathetic nerve contains A. accessory oculomotor nucleus B. superior salivatory nucleus C. inferior salivertory nucleus D. dorsal nucleus of vagus nerve E. sacral parasympathetic nucleus in segments S2~S4 of spinal cord Ⅲ. Answer the following questions 1.Give one example of each spinal, cranial, sympathetic and parasympathetic ganglia, and write out their name, nature and fibrous connections. 2.Write out the origins, position of postganglia neuron and distributions of parasympathetic fibers in vagus nerve Part IV The Endocrine System Learning Objectives You should: 了解内分泌腺的组成、结构特点及功能。(P466-467) 掌握垂体、甲状腺、甲状旁腺、肾上腺、松果体的形态和位置 endocrine glands: have no ducts, their secretions (hormone) release Composition directly into bloodstream to its target organ endocrine tissue Ⅰ.Thyroid gland — H-shape A. Shape and position 94 1. Left and right lobes: lie on either side of inferior part of larynx and superior part of trachea, extend from middle of thyroid cartilage to level of sixth trachea cartilage 2. Isthmus: overlies 2nd to 4th tracheal cartilage 3. Pyramidal lobe: some times arises from isthmus B. Fibrous capsule: a sheath of pretracheal fascia which is attached to arch of cricoid and thyroid cartilages, hence, the thyroid gland moves with larynx during swallowing and oscillates during speaking C. Function: to produce thyroxin, regulating the rate of metabolism and growth of bony and nervous system Ⅱ. Parathyroid gland — yellowish-brown, ovoid bodies A. Position 1. Two superior parathyroid glands: lie at junction of superior and middle third of posterior border of thyroid gland 2. Two inferior parathyroid glands: lie near the inferior thyroid artery, close to the inferior poles of thyroid gland B. Function: regulate calcium and phosphate balance and is therefore essential for life Ⅲ. Suprarenal gland A. Shape and position 1. Right is pyramidal in shape, left one semilunar in shape, consisting of out cortex and inner medulla 2. Located retroperitoneally, superomedial to superior poles of each kidney, enclose with the kidney by the renal fascia B. Function: secretes adrenaline, noradrenaline and several steroid hormones Ⅳ. Hypophysis A. Shape and position 1. Pea-sized organ, attached by infundibulum to hypothalamus, lies in hypophysial fossa 2. Consists of two parts: adenohypophysis and neurohypophysis B. Relationship 1. Above-diaphragm sellae 95 2. Anterosuperior-optic chiasma and optic nerve 3. Laterally-cavernous sinus 4. Below-sphenoid sinus Ⅴ. Pineal body: locates in posterosuperior to thalamus, attached by stalk to posterior part of roof of third ventricle Ⅵ. Thymus: A. Position: located in superior mediastinum, posterior to sternum and between the lungs B. Function: 1. Secrets thymosin: to aid in maturation of T-cell 2. Secrets thymopoietin Ⅶ. Pancreatic islet testis endocrine tissue Ⅷ. Gonad ovary 96