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I. Overview II. Brain Stem III. Cerebellum IV. Diencephalon V. Brain Cerebrum VI. Cranial Nerves 1 I. Overview A.Function B.Protection C.Blood Supply D.Cerebrospinal Fluid II. Brain Stem III. Cerebellum IV. Diencephalon V. Cerebrum VI. Cranial Nerves Brain 2 The Brain and Cranial Nerves 1. Sensations 2. Memory 3. Emotions 4. Decision making 5. Behavior 3 Principal Parts of the Brain 1. Cerebrum Cerebrum 2. Diencephalon a) Thalamus b) Hypothalamus 3. Cerebellum 4. Brainstem a) Medulla Diencephalon b) Pons c) Midbrain Brain Stem Cerebellum 4 Protective Coverings of the Brain Bone Periosteum And Bone Periosteum Meninges same as around the spinal cord 1. dura mater 2. arachnoid mater 3. pia mater Dura Mater Arachnoid Mater Pia Mater 5 Protective Coverings of the Brain Falx cerebri Dura mater extensions 1. falx cerebri 2. tentorium cerebelli 3. falx cerebelli Tentorium cerebelli Falx cerebelli 6 Ependymal cells Blood Supply to Brain Arterial blood supply is branches from circle of Willis on base of brain Capillary Fluid O2 Elec. Vessels on surface of brain---penetrate tissue Glucose Uses 20% of our bodies oxygen & glucose needs blood flow to an area increases with activity in that area deprivation of O2 for 4 min does permanent injury at that time, lysosome release enzymes waste 7 Ependymal cells Blood Supply to Brain Blood-brain barrier (BBB) Capillary Fluid O2 protects cells from some toxins and pathogens Elec. Glucose proteins & antibiotics can not pass but alcohol & anesthetics do tight junctions seal together epithelial cells, continuous basement membrane, astrocyte processes covering capillaries waste 8 Cerebrospinal Fluid (CSF) 80-150 ml (3-5oz) Clear liquid containing glucose, proteins, & ions Functions 1. mechanical protection floats brain & softens impact with bony walls 2. chemical protection optimal ionic concentrations for action potentials 3. circulation nutrients and waste products to and from bloodstream 9 Origin of CSF Lateral Ventricles Choroid plexus Choroid plexus = capillaries covered by ependymal cells 2 lateral ventricles, one within each cerebral hemisphere roof of 3rd ventricle fourth ventricle Third Ventricles Fourth Ventricles 10 Drainage of CSF from Ventricles One median aperture & two lateral apertures allow CSF to exit from the interior of the brain Lateral aperture Median aperture 11 I. Overview II. Brain Stem A.Medulla Oblongata B.Pons C.Midbrain D.Reticular Formation III. Cerebellum IV. Diencephalon V. Cerebrum VI. Cranial Nerves Brain 15 Medulla Oblongata Continuation of spinal cord Ascending sensory tracts Descending motor tracts Nuclei of 5 cranial nerves Cardiovascular center force & rate of heart beat diameter of blood vessels Respiratory center Medulla medullary rhythmicity area sets basic rhythm of breathing Information in & out of cerebellum Reflex centers for coughing, sneezing, swallowing etc 16 Ventral Surface of Medulla Oblongata Ventral surface bulge pyramids large motor tract decussation of most fibers left cortex controls right muscles Olive = olivary nucleus neurons send input to cerebellum proprioceptive signals gives precision to movements 17 Dorsal Surface of Medulla Oblongata Nucleus gracilis & nucleus cuneatus = sensory neurons relay information to thalamus on opposite side of brain 5 cranial nerves arise from medulla -- 8 thru 12 CN 7 CN 8 CN 9 CN 10 CN 11 CN 12 Nucleus gracilis Nucleus 18 cutaneous Injury to the Medulla Hard blow to the back of the head may be fatal Cranial nerve malfunctions on same side as injury; loss of sensation or paralysis of throat or tongue; irregularities in breathing and heart rhythm 19 Pons One inch long White fiber tracts ascend and descend Pneumotaxic & apneustic areas help control breathing Middle cerebellar peduncles carry sensory info to the cerebellum Pons Cranial nerves 5 thru 7 20 Midbrain Third ventricle One inch in length Cerebral aqueduct Extends from pons to diencephalon Cerebral aqueduct connects 3rd ventricle above to 4th ventricle below Midbrain Fourth 21 ventricle Midbrain in Section Cerebral peduncles Red nucleus clusters of motor & sensory fibers Substantia nigra Substantia nigra helps controls subconscious muscle activity Dopamine Red nucleus rich blood supply & ironcontaining pigment cortex & cerebellum coordinate muscular movements by sending information here from the cortex and cerebellum Cerebral peduncles 22 Dorsal Surface of Midbrain Superior colliculi Corpora quadrigemina superior colliculi inferior colliculi coordinate eye movements with visual stimuli Inferior colliculi coordinate head movements with auditory stimuli 23 Midbrain Superior, middle & inferior peduncles attach to brainstem inferior carries sensory information from spinal cord middle carries sensory fibers from cerebral cortex & basal ganglia superior carries motor fibers that extend to motor control areas Superior peduncles Inferior peduncles 24 Reticular Formation Scattered nuclei in medulla, pons & midbrain Reticular formation Reticular activating system alerts cerebral cortex to sensory signals (sound of alarm, flash light, smoke or intruder) to awaken from sleep maintains consciousness & helps keep you awake with stimuli from ears, eyes, skin and muscles Motor function is involvement with maintaining muscle tone 25 I. Overview II. Brain Stem III. Cerebellum IV. Diencephalon V. Brain Cerebrum VI. Cranial Nerves 26 Cerebellum Vermis 2 cerebellar hemispheres and vermis (central area) Function correct voluntary muscle contraction and posture based on sensory data from body about actual movements sense of equilibrium 27 Cerebellum Transverse fissure between cerebellum & cerebrum Cerebellar cortex (folia) & central nuclei are grey matter Arbor vitae = tree of life = white matter 28 I. Overview II. Brain Stem III. Cerebellum IV. Diencephalon A.Thalamus B.Hypothalamus Brain C.Epithalamus D.Circumventricular Organs V. Cerebrum VI. Cranial Nerves 29 Diencephalon Surrounds 3rd Ventricle Thalamus (enclosed in 3rd ventricle) Surrounds 3rd ventricle Superior part of walls is thalamus Inferior part of walls & floor is hypothalamus Hypothalamus 30 Thalamus 1 inch long mass of gray mater in each half of brain (connected across the 3rd ventricle by intermediate mass) Thalamus (enclosed in 3rd ventricle) Relay station for sensory information on way to cortex Crude perception of some sensations 31 Thalamic Nuclei Nuclei have different roles relays auditory and visual impulses, taste and somatic sensations receives impulses from cerebellum or basal ganglia anterior nucleus concerned with emotions, memory and acquisition of knowledge (cognition) Emotions Emotions Emotions, Alertness, Memory Auditory Integrates with other nuclei Visual Motor 32 Hypothalamus Dozen or so nuclei in 4 major regions mammillary bodies are relay station for olfactory reflexes infundibulum suspends the pituitary gland Major regulator of homeostasis Smell receives somatic and visceral input, taste, smell & hearing information; monitors osmotic pressure, temperature of blood Connects to pituitary gland Pituitary gland 33 Functions of Hypothalamus Controls and integrates activities of the ANS which regulates smooth, cardiac muscle and glands Synthesizes regulatory hormones that control the anterior pituitary Contains cell bodies of axons that end in posterior pituitary where they secrete hormones Regulates rage, aggression, pain, pleasure & arousal Feeding, thirst & satiety centers Controls body temperature Regulates daily patterns of sleep Smell Connects to pituitary gland Pituitary gland 34 Epithalamus Pineal gland Pineal gland endocrine gland the size of small pea secretes melatonin during darkness promotes sleepiness & sets biological clock Habenular nuclei emotional responses to odors Habenular nuclei 35 Subthalamus & CVO Subthalamus small area just inferior to thalamus work with basal ganglia, cerebrum & cerebellum to control body movements Circumventricular organs in walls of 3rd & 4th ventricles monitor changes in blood chemistry because lack blood brain barrier (parts of hypothalamus, pineal & pituitary gland) sites of entry of HIV virus into brain (dementia) 36 I. Overview II. Brain Stem III. Cerebellum IV. Diencephalon V. Cerebrum VI. A. Lobes B. White Matter C. Basal Ganglia D. Limbic System E. Function of Cortex 1. Sensory 2. Motor 3. Association 4. Lateralization 5. Brain Waves Cranial Nerves Brain 37 Cerebrum (Cerebral Hemispheres) Cerebral cortex is gray matter overlying white matter Gray matter White matter 2-4 mm thick containing billions of cells grew so quickly formed folds (gyri) and grooves (sulci or fissures) 38 Cerebrum (Cerebral Hemispheres) Longitudinal fissure Corpus callosum Longitudinal fissure separates left & right cerebral hemispheres Corpus callosum is band of white matter connecting left and right cerebral hemispheres 39 Lobes and Fissures Each hemisphere is subdivided into 4 lobes 1. Frontal lobe 2. Motor area Personality, behavior Emotions Memory Occipital Temporal Somatosensory – skin and muscle Occipital lobe 4. Parietal Parietal lobe 3. Frontal Vision Temporal lobe Hearing Smell Taste 40 Lobes and Fissures Central sulcus (black) precentral & postcentral gyrus Frontal Parietal Occipital Temporal Parieto-occipital sulcus (red) Lateral sulcus (yellow) 41 Cerebral White Matter Association fibers 1. Association fibers between gyri in same hemisphere 2. Commissural fibers from one hemisphere to other 3. Projection fibers form descending & ascending tracts Commisural fibers Projection fibers 43 Basal Ganglia Connections to red nucleus, substantia nigra & subthalamus Caudate Input & output with cerebral cortex, thalamus & hypothalamus Control large automatic movements of skeletal muscles Parkinson’s Disease Putamen Globus pallidus 44 Limbic System Emotional brain intense pleasure & intense pain Strong emotions increase efficiency of memory 45 Sensory Areas of Cerebral Cortex Receive sensory information from the thalamus Primary somatosensory area = postcentral gyrus = 1,2,3 Primary visual area = 17 Primary auditory area = 41 & 42 Primary gustatory area = 43 47 Motor Areas of Cerebral Cortex Voluntary motor initiation Primary motor area = 4 = precentral gyrus controls voluntary contractions of skeletal muscles on other side Motor speech area = 44 = Broca’s area production of speech -control of tongue & airway 48 Association Areas of Cerebral Cortex Somatosensory area = 5 & 7 (integrate & interpret) Visual association area = 18 & 19 (recognize & evaluate) Auditory association area(Wernicke’s) = 22(words become speech) Gnostic area = 5,7,39 & 40 (integrate all senses & respond) Premotor area = 6 (learned skilled movements such as typing) Frontal eye field =8 (scanning eye movements such as phone book) 49 Hemispheric Lateralization Functional specialization of each hemisphere more pronounced in men Females have larger connections between 2 sides Damage to left side produces aphasia Damage to same area on right side produces speech with little emotional inflection 51 Electroencephalogram (EEG) Brain waves are millions of nerve action potentials in cerebral cortex diagnosis of brain disorders (epilepsy) brain death (absence of activity in 2 EEGs 24 hours apart) 1. Alpha -- awake & resting 2. Beta -- mental activity 3. Theta -- emotional stress 4. Delta -- deep sleep 52 I. Overview II. Brain Stem III. Cerebellum IV. Diencephalon V. Brain Cerebrum VI. Cranial Nerves 53 Cranial Nerves I. Olfactory II. Optic III. Oculomotor IV. Trochlear V. Trigeminal VI. Abducens VII. Facial CN I CN II CN III CN IV CN V CN VI CN VII VIII. Vestibulocochlear IX. CN VIII Glossopharyngeal CN IX X. Vagus CN X XI. XII. Accessory CN XI hypoglossal 54 CN XII I -- Olfactory Nerve (S) Extends from olfactory mucosa of nasal cavity to olfactory bulb Sense of smell Anosmia – loss of smell 55 II -- Optic Nerve (S) Visual field defect Connects to retina supplying vision Defect in Visual acuity defect Visual acuity Visual field 56 III = Oculomotor Nerve (S/M) Sensory: Diplopia – double vision Proprioception – sense of position Motor: Levator palpebrae raises eyelid Ptosis – drooping of eyelid 4 extrinsic eye muscles Superior, medial, inferior, and inferior oblique 2 intrinsic eye muscles accomodation for near vision (changing shape of lens during reading) constriction of pupil 57 IV = Trochlear Nerve (M) Sensory: Proprioception – sense of position Motor: Superior oblique eye muscle 58 V = Trigeminal Nerve S/M) Sensory: Tic douloureux - severe, stabbing pain to one side of the face. touch, pain, & temperature receptors of the face 1. ophthalmic branch 2. maxillary branch 3. mandibular branch Motor: muscles of mastication 59 VI = Abducens Nerve (S/M) Sensory: Proprioception – sense of position Motor: Lateral rectus eye muscle 60 VII = Facial Nerve (S/M) Sensory: taste buds on anterior 2/3’s of tongue Bell’s Palsy Motor: facial muscles salivary & nasal and oral mucous glands & tears 61 VIII = Vestibulocochlear Nerve (S/M) Cochlear branch begins in medulla receptors in cochlea hearing if damaged deafness or tinnitus (ringing) is produced Vestibular branch begins in pons receptors in vestibular apparatus sense of balance vertigo (feeling of rotation) ataxia (lack of coordination) 62 IX = Glossopharyngeal Nerve (S/M) Sensory: Somatic sensations & taste on posterior 1/3 of tongue Motor: Stylopharyngeus m. (lifts throat during swallowing) Secretions of parotid gland 63 X = Vagus Nerve (S/M) Sensory: Receives sensations from viscera Motor: Controls cardiac muscle and smooth muscle of the viscera Controls secretion of digestive fluids Bradycardia 64 XI = Spinal Accessory Nerve (S/M) Cranial portion arises medulla skeletal mm of throat & soft palate Spinal portion arises cervical spinal cord sternocleidomastoid and trapezius mm. 65 XII = Hypoglossal Nerve (S/M) Sensory: Proprioception – sense of position Motor: Controls muscles of tongue during speech and swallowing Injury deviates tongue to injured side when protruded 66