Download The Cranial Nerves

The Nervous System
• Major division - Central
vs. Peripheral中枢/外周
• Central or CNS- brain
and spinal cord脑和脊髓
• Peripheral- nerves
connecting CNS to
muscles and organs
Central Nervous System
Peripheral Nervous System
中枢/外周神经功能分类.
♠ Sensory division brings information regarding the
int. or ext. environment into the CNS
♠ Motor division issues directives out to muscle or
glandular tissue
♣Somatic nervous system services skeletal muscle
♣ Autonomic nervous system services smooth
&cardiac muscle:
♦ Sympathetic nervous system is responsible for the "fightor-flight"response;
♦ Parasympathetic nervous system is responsible for the
"rest-anddigest"response
Divisions of the
Nervous System
• Central Nervous System
• Peripheral Nervous System
• nerves
• cranial nerves
• spinal nerves
The Spinal Cord
1. External features:
 Location:
foramen magnum -- lower
border of first lumbar vertebra
 Shape:
A long cylindrical structure
 Enlargements:
cervical enlargement
lumbar [lumbosacral]
enlargement
 Conus medullaris脊髓圆锥
 Filum terminale : a condensation of
pia mater, S2，终丝
Conus edullaris :caudal
to the lumbosacral
enlargement the spinal cord
tapers gradully& becomes the
conical termination
Filum termination: a
condensation of pia mater
forms~
Cauda equina: 马尾
lumbosacral roots
descend ,sourrounding the
filum terminale..
• main longitudinal fissure and sulci on surface:
Cauda equina
posterior lateral posterior median sulcus
sulcus
Filum terminale
sulcus
anterior lateral
fissure
anterior median
• Spinal segment:
It's a part of spinal cord, which is connected
with the rootlets of a pair of spinal nerve.
• 31 segments
8 cervical segments
12 thoracic segments
5 lumbar segments
5 sacral segments
1 coccygeal segments
• Corresponding relationship between
spinal segments and vertebrae
spinal segments
C1-C4
C5 ~ T8, T l~ T4
correspond to vertebrae
C1-C4
C4 - C7, C7 ~ T3
T5 ~ T8
T3 ~ T6
T9-T12
T6-T9
L1-L5
T10-T12
S l~S5,Co1
LI
2. Internal structure
• The central canal
• Gray matter:
 parts:
 Lateral horn
(only extends from
Tl to L3 segments.)
 gray commissure
(anterior and posterior )
central canal
posterior horn
Intermediate
zone
Lateral horn
anterior horn
Gray matter
gray commissure
• Gray matter
– anterior horn
– posterior horn
– intermediate
zone
• White matter
– anterior funiculus
– posterior funiculus
– Lateral funiculus
• White matter:
 parts:
posterior median sulcus
posterior funiculus
posterior lateral sulcus
lateral
funiculus
anterior lateral sulcus
anterior white
commissure
anterior median
fissure
anterior funiculus
 Main tracts (or fasciculi):
long ascending tracts:
• fasciculus gracilis薄束: come from
sacral, lumbar and lower eight
thoracic nerves, terminate upon
nucleus gracilis
• fascicules cuneatus楔束: come from
cervical and upper fouth thoracic
nerves, terminate upon nucleus
cuneatus.
• *conduct the fine [discriminating] tactile
(e.g.two-point discrimination ) & kinesthetic
sense (e.g.position , movement &vibration)of
the ipsilateral trunk & limbs.
fascicules
cuneatus
fascicules
gracilis
• lateral & anterior spinothalamic tracts:
thalamus
脊髓丘脑束
• *in corresponding funiculus
• *arises from opposite nucleus
proprius
• *terminate on thalamus
• *conduct pain, thermal and
rough tactile sense of opposite
trunk and limbs
anterior
spinothalamic
tracts
anterior
spinothalami
c
tracts
nucleus proprius
 main long descending tracts
lateral corticospinal tract:
皮质脊髓侧束
*arises from opposite cerebral
cortex
*descends through lateral
funiculus of spinal cord
*terminate on ipsilateral
anterior horn (lateral group)
*controls the contraction of
skeletal muscles of ipsilateral
limbs
anterior corticospinal tract:
*controls the movement of
bilateral muscles of trunk
lateral
corticospinal
tract
anterior
corticospinal
tract
 Functions:
• To convey afferent impulses, which come from
somatic and visceral receptors to the brain, and
conduct efferent impulses from brain to effectors.
• Related to reflexes,e.g., the stretch reflex, the
reflex of bladder & rectal emptying
Spinal Reflexes
•Programmed stereotypical
reactions that occur in response
to stimuli
•Simplest reflex: monosynaptic
stretch reflex
•Reflexes are subject to higher
level control
Peripheral Nervous System
Peripheral Nervous System
Skeletal
(Somatic)躯体
AutonomiC内脏
SympathetiC交感 ParasympathetiC副交感
Somatic System
• Nerves to/from
spinal cord
– control muscle
movements
– somatosensory inputs
• Both Voluntary
and reflex
movements
• Skeletal Reflexes
– simplest is spinal
reflex arc
Brain
Sensory
Neuron
Skin receptors
Motor
Neuron
Interneuron
Muscle
Autonomic System
• Two divisions:
– Sympathetic nerve交感神经
– Parasympatheitic nerve副交感神经
• Control involuntary functions
–
–
–
–
–
heartbeat
blood pressure
respiration
perspiration
digestion
• Can be influenced by thought and emotion
Sympathetic
• “ Fight or flight”
response
• Release adrenaline
and noradrenaline
• Increases heart rate
and blood pressure
• Increases blood
flow to skeletal
muscles
• Inhibits digestive
functions
CENTRAL NERVOUS SYSTEM SYMPATHETIC
Brain
Dilates pupil
Stimulates salivation
Relaxes bronchi
Spinal
cord
Salivary
glands
Lungs
Accelerates heartbeat
Inhibits activity
Heart
Stomach
Pancreas
Stimulates glucose
Secretion of adrenaline,
nonadrenaline
Relaxes bladder
Sympathetic Stimulates ejaculation
ganglia
in male
Liver
Adrenal
gland
Kidney
Parasympathetic
• “ Rest and digest ”
system
• Calms body to
conserve and
maintain energy
• Lowers heartbeat,
breathing rate,
blood pressure
CENTRAL NERVOUS SYSTEM PARASYMPATHETIC
Brain
Contracts pupil
Stimulates salivation
Spinal
cord
Constricts bronchi
Slows heartbeat
Stimulates activity
Stimulates gallbladder
Gallbladder
Contracts bladder
Stimulates erection
of sex organs
Summary of autonomic
differences
Autonomic nervous system controls physiological arousal
Sympathetic
division (arousing)
Pupils dilate
Decreases
Parasympathetic
division (calming)
EYES
Pupils contract
SALVATION
Increases
Perspires
SKIN
Dries
Increases
RESPERATION
Decreases
Accelerates
HEART
Slows
Inhibits
DIGESTION
Activates
Secrete stress
hormones
ADRENAL
GLANDS
Decrease secretion
of stress hormones
Sympathetic Division
• Myelinated preganglionic exit spinal cord in
ventral roots at T1 to L2[L3] levels.
• Travel to ganglia at different levels to synapse
with postganglionic neurons.
• Divergence:
– Preganglionic fibers branch to synapse with
numerous postganglionic neurons.
Sympathetic Division
• Axons of postganglionic neurons are
unmyelinated to the effector organ.
• Preganglionic neuron is short.
• Post-ganglionic neuron is long.
Parasympathetic Division
• Preganglionic fibers originate in midbrain,
medulla, and pons; and in the 2-4 sacral
levels of the spinal cord.
• Preganglionic fibers synapse in ganglia
located next to or within organs innervated.
• Do not travel within spinal nerves.
– Do not innervate blood vessels, sweat glands,and
arrector pili muscles.
Parasympathetic Division
• 4 of 12 pairs of cranial nerves contain
preganglionic parasympathetic fibers.
• Preganglionic fibers are long,
postganglionic fibers are short.
• Vagus:
– Innervate heart, lungs esophagus, stomach,
pancreas, liver, small intestine and upper half of
the large intestine.
Parasympathetic Division
• Preganglionic fibers from the sacral
level innervate the lower half of large
intestine, the rectum, urinary and
reproductive systems.
Spinal Nerves and Vertebrae
Cross Section II
Ventral and Dorsal Roots
Ventral and Dorsal Roots
THE PERIPHERAL
NERVOUS SYSTEM ----
The Spinal Nerves 1.
General Description
 31 Pairs of Spinal Nerves
Cervical Nerves : 8 pairs
Thoracic Nerves : 12 pairs
Lumbar Nerves : 5 pairs
Sacral Nerves : 5 pairs
Coccygeal Nerves : 1 pair
Four Types of Fibers in Spinal Nerves
– The Somatic afferent (sensory) Fibers
- The Visceral afferent (sensory) Fibers
– The Somatic efferent (motor) Fibers
- The Visceral efferent (motor) Fibers
Four Branches of a Spinal Nerves
– Anterior Branch Posterior Branch
– Meningeal Branch Communicating Branches
Four Branches of a Spinal Nerves
Four Plexuses
– Cervical Plexus颈丛
– Brachial Plexus臂丛
– Lumbar Plexus腰丛
– Sacral Plexus骶丛
• The thoracic nerves
are separated from
each other.
The cervical Plexus
• The Formation of the Cervical Plexus:
• The anterior branches of the 1st to 4th cervical nerves [C1~4]
• The Superficial Branches
（sternocleidomastoid m.)
The lesser occipital nerve
The great auricular nerve
The transverse nerve of neck
The supraclavicular nerves
• The Deep Branches
– The phrenic nerve
The Brachial Plexus (scalene fissure, axilla)
 formation: root(C5 – T1)
trunk
division
cord
branches and distribution
Brachial plexus : the long thoracic
lateral cord
Medial cord
Posterior cord
the musculocutaneous nerve
lateral pectoral nerve
the median nerve
the ulnar nerve
medial pectoral nerve
the radial nerve
the axillary nerve
the thoracodorsal nerve
the musculocutaneous n.
the axillary n.
the long thoracic n.
median n.
the ulnar n.
medial pectoral n.
lateral pectoral n.
the radial n.
the thoracodorsal n.
• The musculocutaneous nerve
♠ Major end branch of lateral cord
♠ Runs down lateral aspect of upper limb
♠ Innervates forearm flexors (biceps, brachialis)
and provides cutaneous sensation for lateral
forearm
• The median nerve
♠ Does not branch in arm (humeral region of
upper limb)
♠ In forearm, innervates flexors and skin
♠ In hand, innervates some muscles of lateral
palm
♠ The median nerve serves muscles which pronate
the forearm,flex the wrist and fingers and
oppose the thumb
• The ulnar nerve
♠ Branches off median cord.
♠ Runs along medial aspect of arm, swings behind the
medial epicondyle, then parallels the ulna as it courses
down the medial forearm
♠ Innervates flexor carpi ulnaris & flexor digitorum
profundus; Supplies most of the muscles & skin of the
medial hand
♠ Along with median nerve, the ulnar nerve produces
wrist &finger flexion &adduction & abduction of medial fingers
♣ The "funny bone" is the ulnar nerve as it passes behind
the medial epicondyle.
♠ Loss of function of the ulnar nerve results in clawhand as
the little and ring fingers become hyperextended at the
knuckles and flexed at the distal interphalangeal joints
• The radial nerve
Largest branch of the brachial plexus; continuation of
the posterior cord,wraps around posterior humerus,
swings up & over the lateral epicondyle &the divides
into a superficial branch &a deep branch
♣ Superficial branch, runs along lateral edge of radius
♣ Deep branch,runs into posterior forearm
♠ Radial nerve innervates nearly all extensors in the
upper limb,produces extension of elbow (triceps),
supination of forearm (supinator, brachioradialis, but
not biceps), extension of wrist & fingers (forearm and
digital extensors), and abduction of thumb
♠ Loss of function of the radial nerve results in wrist drop,
Radial Nerve
The Anterior Branches of the Thoracic
Nerves
——Intercostal and subcostal nerve
The segmental distribution of the anterior branches of
the thoracic nerves
T2: the sternal angle
T8: the costal arch
T4: the nipple
T10: the umbilicus
T6: the xiphoid process
T12: the anterior
superior iliac spin
The Lumbar Plexus
• The formation of the lumbar plexus:
T12 (part)+L1~3+L4 (part)
The branches of the lumbar plexus
The iliohypogastric nerve
The ilioinguinal nerve
The lateral femoral
cutaneous nerve
The femoral nerve
The obturator nerve
The genitofemoral nerve
The Sacral Plexus
• The formation of the sacral plexus
The lumbosacral trunk(L4~5)+S1~5+Co
The branches of the sacral plexus
–The superior gluteal n.
–The inferior gluteal n.
–The pudendal n.
The anal nerves
The perineal nerve
The dorsal nerve of
penis or clitoris
The branches of
- The the
posterior
femoral
sacral plexus
cutaneous n.
The sciatic nerve
(Poplited fossa)
•The tibial nerve
•(hook-like foot)
•The common peroneal
nerve
(talipes equinovarus)
The superficial peroneal
nerve
The deep peroneal nerve
体表节段分布
The Cranial Nerves
脑神经
The cranial nerve
Ⅰ. Olfactory nerve
Ⅱ. Optic nerve
Ⅲ. Oculomotor nerve
Ⅳ. Trochlear nerve
Ⅴ. Trigeminal nerve
Ⅵ. Abducent nerve
Ⅶ. Facial nerve
Ⅷ. Vestibulocochlear nerve
Ⅸ. Glossopharyngeal nerve
Ⅹ. Vagus nerve
Ⅺ. Accessory nerve
Ⅻ. Hypoglossal nerve
Names of cranial nerves
2. The cranial nerves consist of 4 kinds of fibers:
somatic sensory fibers
visceral sensory fibers
somatic motor fibers
visceral motor fibers
3 types:
Sensory (afferent) nerves: I、Ⅱ、Ⅷ
Motor (efferent) nerves: III、Ⅳ、Ⅵ、Ⅺ、Ⅻ
Mixed nerves: Ⅴ、Ⅶ、Ⅸ、Ⅹ
Three types of cranial nerves
• Sensory cranial nerves: contain only afferent (sensory) fibers
– ⅠOlfactory nerve
– ⅡOptic nerve
– Ⅷ Vestibulocochlear nerve
• Motor cranial nerves: contain only efferent (motor) fibers
–
–
–
–
–
Ⅲ Oculomotor nerve
Ⅳ Trochlear nerve
ⅥAbducent nerve
Ⅺ Accessory nerv
Ⅻ Hypoglossal nerve
• Mixed nerves: contain both sensory and motor fibers--–
–
–
–
ⅤTrigeminal nerve,
Ⅶ Facial nerve,
ⅨGlossopharyngeal nerve
ⅩVagus nerve
4 Classification - Cranial Nerves
1. Sensory nerves:
–
carry somatic sensory information:
•
touch, pressure, vibration, temperature, and pain
2. Special sensory nerves:
–
carry sensations:
•
smell, sight, hearing, balance
3. Motor nerves:
–
axons of somatic motor neurons
4. Mixed nerves:
–
mixture of motor and sensory fibers
The sensory nerves:
1. Olfactory nerve:
•
Visceral sensory fibers
•
Cell bodies are in nasal
Mucosa olfactory region
(on the superior
nasal concha and opposed
part of nasal septum)
•
Pierces through
cribriform
foramina and ends in
olfactory bulb.
•
Conducts sense of smell.
Optic nerve(II)
• Primary function:
– special sensory (vision)
• Origin: retina of eye
• Pathway:
– optic canals of sphenoid
• Destination:
– diencephalon via optic chiasm
• Structures
– Optic chiasm: where sensory fibers converge , and cross to
opposite side of brain
– Optic tracts: reorganized axons, leading to lateral geniculate
nuclei
The sensory nerves--:
2. Optic nerve
somatic sensory fibers.
The central processes of ganglion cells
of retina converge on optic disc, then
pierce the sclera and form optic nerve.
passes through optic canal into middle
cranial fossa, then joints optic
chiasma.
superior obliquus
Oculomotor nerve
The general somatic
motor fibers
diplopia
Trochlear n.
Abducent n.
lateral rectus
ciliary muscle
The general visceral
motor fibers
sphincter pupillae
muscles
Oculomotor nerve
• Components
– General somatic efferent fibers (GSE)
– General visceral efferent fibers (GVE)
• Main action－supplies
– Superior, inferior and medial recti; inferior obliquus; levator
palpebrae superioris
– Sphincter pupillea and ciliary muscle
• Ciliary ganglion: lies between optic nerve and lateral rectus
Oculomotor nerve
The Trochlear Nerves (IV)
• Primary function:
– motor (eye movements)
• Origin: mesencephalon
• Pathway: superior orbital fissure of sphenoid
• Destination: superior oblique muscle
Figure 14–21
Trochlear nerve (IV) :
• Emerges from anterior medullary velum
just behind the inferior colliculus—winds
forward around cerebral peduncle—
traverses lateral wall of cavernous sinus
—passes into orbit through the superior
orbital fissure
• Supplies the superior oblique muscle.(diplopia )
Abducens
nerve (VI)
• enters the orbit through the superior orbital fissure.
•
Innervates the lateral rectus
Oculamotor paralysis
Abducent nerve injury
V. Trigeminal nerve:
 It has a motor and a sensory
roots.The motor root contains
the somatic motor fibers arising
from the motor nucleus of trigeminal
nerve; Sensory root contains the
somatic sensory fibers which are
central processes of the neurons
located in the trigeminal ganglion.
 It’s formed by the peripheral processes of neurons of trigeminal
ganglion and few somatic motor fibers.
 3 divisions:
—ophthalmic nerve
—maxillary nerve
—mandibular nerve
Trigeminal nerve [V]
Trigeminal nerve [V]
Components of fibers
• Somatic motor fibers: originate from motor
nucleus of trigeminal nerve, and supply
masticatory muscles
• Somatic sensory 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
Facial nerve: [VII]
• contains 3 [+1] types of fibers:
--- somatic motor fibers:
arise from the facial nucleus
--- visceral motor fibers:
arise from the superior salivatory
nucleus.
--- visceral sensory fibers:
arise from the geniculate ganglion
and terminate in the nucleus of solitary tract.
• Emerges from the pontomedullary groove just medially to the
vestibulocochlear n. [Somatic sensory fibers from skin of external ear ]
• Branches outside the
facial canal:
--- temporal branch
--- zygomatic branches
--- buccal branches
--- mandibular branch
--- cervical branch
(contain the somatic
motor fibers –
mimetic muscles and
platysma)
Branches within the facial canal
• Chorda tympani : joins lingual branch of mandibular nerve:To
taste buds on anterior two-thirds of tongue;Relayed in
submandibular ganglion, the postganglionic fibers
supply submandibular & sublingual glands
Injury to the facial nerve
Vestibulocochlear nerve [VIII]
somatic sensory fibers
Vestibular ganglion(SSA) ↘
↗ Vestibular nuclei
Internal acoustic meatus
Cochlear ganglion (SSA) ↗
↘ Cochlear nuclei
VIII. Vestibulocochlear nerve:
Somatic sensory fibers consists of cochlear
&vestibular nerves.
Cochlear nerve is formed by central processes of
bipolar cells of cochlear ganglion in the central
modiolus of cochlea.
Vestibular nerve is formed by central processes
of cells of vestibular ganglion.
passes into brain stem through internal acoustic
meatus. Conducts sense of hearing& balance
Glossopharyngeal nerve (Ⅸ)
Components of fibers
• Somatic motor fibers: originate from nucleus ambiguus, and
supply stylopharygeus
• Visceral motor fibers: arise from inferior salivatory nucleus and
ralyed in otic ganglion, the postganglionic fibers supply parotid
gland
• Visceral sensory 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
• The 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. Sensation from skin of posterior surface of auricle …
Glossopharyngeal Nerves (IX)
• Primary function:
– mixed (sensory and motor) to head and neck
• Origins:
– sensory:
• posterior 1/3 of tongue
• part of pharynx and palate
• carotid arteries
– motor:
• motor nuclei of medulla oblongata
• Pathway:
– jugular foramina between occipital and temporal bones
Vagus nerve (Ⅹ)
components of fibers
• originate from dorsal nucleus of vagus nerve,
synapse in parasympathetic ganglion, short
postganglionic fibers innervate cardiac muscles,
smooth muscles and glands of viscera
• originate from ambiguus, to muscles of pharynx
and larynx
• carry impulse from viscera in neck, thoracic and
abdominal cavity to nucleus of solitary tract
• sensation from auricle, external acoustic meatus
and cerebral dura mater
• Main branches:
— superior laryngeal n.
* internal laryngeal n.(mucous
membrane of larynx above
the level of vocal folds)
* external laryngeal n.(supplies
the cricothyroid m.)
— cervical cardiac branches
— pharyngeal branch
• Main branches:
— recurrent laryngeal nerve,ascends in groove between the trachea
and esophagus— enters larynx): mucous membrane of the larynx
below the level of vocal folds and rest m. of larynx.
• Main branches:
— bronchial branches
— esophageal branches
— anterior and posterior
gastric branches(stomach)
— hepatic branches
— celiac branches
XI. Accessory nerve
• Contains somatic motor fibers arising
from the accessory nucleus(spinal root)
and lower part of nucleus ambiguus
(cranial root).
• Emerges from the posterolateral sulcus
of medulla oblongata—through the
jugular foramen—descends between
the internal carotid artery and internal
jugular vein—passes back and
downwards to strnocleidomustoid
muscle & trapezius muscles
Accessory Nerves (XI) (1 of 2)
• Primary function:
– motor to muscles of neck and upper
back
• Origin:
– motor nuclei of spinal cord and
medulla oblongata
• Pathway:
– jugular foramina between occipital
and temporal bones
• Destinations:
– internal branch:
• voluntary muscles of palate,
pharynx, and larynx
– external branch:
• sternocleidomastoid and trapezius
muscles
XII. Hypoglossal nerve:
• Emerges from the anterolateral sulcus (between the olive and
pyramid) of medulla oblongat
—through the hypoglossal canal
—descends between the internal
carotid artery and internal
jugular vein—passes forwards
over the internal & external
arteries at the level of the angle
of mandible— enters the tongue.
• Supplies the intrinsic &
extrinsic muscles of tongue
Hypoglossal Nerves (XII)
• Primary function:
– motor (tongue movements)
• Origin:
– motor nuclei of medulla oblongata
• Pathway:
– hypoglossal canals of occipital bone
• Destination:
– muscles of tongue
Summary: Cranial Nerves
Table 14-9 (1 of 2)
Summary: Cranial Nerves
Table 14-9 (2 of 2)
The Cranial Nerves
一嗅二视三动眼，四滑五叉六外展，七面八听九舌咽，
迷.副，舌下神经全。