The Nervous System

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 "fight-or-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 CordThe Spinal Cord1. External features:1. External features: Location:Location: foramen magnum -- lower foramen magnum -- lower border of first lumbar vertebraborder of first lumbar vertebra Shape: Shape: A long cylindrical structure A long cylindrical structure Enlargements:Enlargements: cervical enlargement cervical enlargement lumbar lumbar [[lumbosacrallumbosacral]]

enlargementenlargement Conus medullarisConus medullaris 脊髓脊髓圆锥 Filum terminale : Filum terminale : a condensation ofa condensation of

pia mater, 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 surfacemain longitudinal fissure and sulci on surface: :

Cauda equina Cauda equina

posterior lateral posterior median sulcusposterior lateral posterior median sulcus

anterior lateral anterior mediananterior lateral anterior median

sulcussulcus fissurefissure

sulcussulcus

Filum terminaleFilum terminale

• 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 betweenCorresponding relationship between

spinal segments and vertebraespinal segments and vertebrae

spinal segments correspond to vertebrae spinal segments correspond to vertebrae

C1-C4 C1-C4 C1-C4 C1-C4

C5 ~ T8, T l~ T4C5 ~ T8, T l~ T4 C4 - C7, C7 ~ T3 C4 - C7, C7 ~ T3

T5 ~ T8T5 ~ T8 T3 ~ T6 T3 ~ T6

T9-T12T9-T12 T6-T9 T6-T9

L1-L5L1-L5 T10-T12 T10-T12

S l~S5,Co1 LI S l~S5,Co1 LI

2. Internal structure2. Internal structure

• The central canal The central canal

• Gray matter:Gray matter: parts:parts: Lateral hornLateral horn

(only extends from (only extends from

Tl to L3 segments.)Tl to L3 segments.) gray commissure gray commissure

(anterior and posterior )(anterior and posterior )

Lateral hornLateral horn

posterior hornposterior horn

gray commissuregray commissure

Intermediate Intermediate zonezone

anterior hornanterior horn

central canalcentral canal

Gray matterGray matter

• Gray matter – anterior hornanterior horn– posterior hornposterior horn– intermediate intermediate

zonezone

• White matter– anterior fanterior funiculus

– posterior posterior funiculus

– Lateral funiculus

• White matter:White matter: parts:parts:

posterior funiculus

lateral funiculus

anterior funiculusanterior white commissure

posterior lateral sulcusposterior lateral sulcus

posterior median sulcusposterior median sulcus

anterior lateral sulcusanterior lateral sulcus

anterior mediananterior medianfissurefissure

Main tracts (or fasciculi):Main tracts (or fasciculi):long ascending tractslong ascending tracts::

• fasciculus gracilisfasciculus gracilis 薄束薄束 : : come from come from sacral, lumbar and sacral, lumbar and lower eight lower eight thoracic nerves,thoracic nerves, terminate upon terminate upon nucleus gracilis nucleus gracilis

• fascicules cuneatusfascicules cuneatus 楔束束 : : come fromcome from

cervical and upper fouth thoracic cervical and upper fouth thoracic nerves, terminate upon nucleus nerves, terminate upon nucleus cuneatus. cuneatus.

• **conduct the fine [discriminating] tactile conduct the fine [discriminating] tactile (e.g.two-point discrimination ) & kinesthetic (e.g.two-point discrimination ) & kinesthetic sense (e.g.position , movement &vibration)of sense (e.g.position , movement &vibration)of the ipsilateral trunk & limbs.the ipsilateral trunk & limbs.

fascicules gracilis

fascicules cuneatus

• lateral & lateral & anterioranterior spinothalamic tracts spinothalamic tracts::

脊髓丘脑束• *in corresponding funiculus *in corresponding funiculus • *arises from opposite nucleus*arises from opposite nucleus

propriusproprius• *terminate on thalamus*terminate on thalamus• *conduct *conduct painpain, , thermal thermal and and

rough tactile senserough tactile sense of opposite of opposite

trunk and limbs trunk and limbs

thalamus

anterior spinothalamic tracts

anterior spinothalamictracts

nucleus proprius

main long descending tracts main long descending tracts lateral corticospinal tract:lateral corticospinal tract: 皮质脊髓侧束 **arises from opposite cerebral arises from opposite cerebral cortexcortex **descends through lateral descends through lateral funiculus of spinal cordfuniculus of spinal cord **terminate on ipsilateral terminate on ipsilateral anterior horn (lateral group)anterior horn (lateral group) **controls the contraction of controls the contraction of skeletal muscles of ipsilateral skeletal muscles of ipsilateral limbslimbs anterior corticospinal tract:anterior corticospinal tract: **controls the movement of controls the movement of bilateral muscles of trunkbilateral muscles of trunk

lateral corticospinal tract anterior

corticospinaltract

Functions:Functions:

• To convey afferent impulses, which come from somatic and visceral To convey afferent impulses, which come from somatic and visceral

receptors to the brain, and conduct efferent impulses from brain to receptors to the brain, and conduct efferent impulses from brain to

effectors.effectors.

• Related to reflexes,e.g., the stretch reflex, the reflex of bladder & Related to reflexes,e.g., the stretch reflex, the reflex of bladder &

rectal emptyingrectal emptying

Spinal Reflexes

•Programmed stereotypical reactions that occur in response to stimuli

•Simplest reflex: monosynaptic stretch reflex

•Reflexes are subject to higher level control


Skeletal(Somatic) 躯体

SympathetiC 交感ParasympathetiC 副交感

AutonomiC 内脏


Somatic System

• Nerves to/from spinal cord– control muscle

movements

– somatosensory inputs

• Both Voluntary and reflex movements

• Skeletal Reflexes– simplest is spinal

reflex arc Muscle

MotorNeuron

Interneuron

Skin receptors

SensoryNeuron

Brain

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 SYSTEMBrain

Spinalcord

SYMPATHETIC

Dilates pupil

Stimulates salivation

Relaxes bronchi

Accelerates heartbeat

Inhibits activity

Stimulates glucose

Secretion of adrenaline,nonadrenaline

Relaxes bladder

Stimulates ejaculationin male

Sympatheticganglia

Salivaryglands

Lungs

Heart

Stomach

Pancreas

Liver

Adrenalgland

Kidney

Parasympathetic

• “ Rest and digest ” system

• Calms body to conserve and maintain energy

• Lowers heartbeat, breathing rate, blood pressure

CENTRAL NERVOUS SYSTEMBrain

PARASYMPATHETIC

Spinalcord

Stimulates salivation

Constricts bronchi

Slows heartbeat

Stimulates activity

Contracts bladder

Stimulates erectionof sex organs

Stimulates gallbladder

Gallbladder

Contracts pupil

Summary of autonomic differences

Autonomic nervous system controls physiological arousal

Sympatheticdivision (arousing)

Parasympatheticdivision (calming)

Pupils dilate EYES Pupils contract

Decreases SALVATION Increases

Perspires SKIN Dries

Increases RESPERATION Decreases

Accelerates HEART Slows

Inhibits DIGESTION Activates

Secrete stresshormones

ADRENALGLANDS

Decrease secretionof 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.


• 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.


• 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

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) FibersThe Somatic afferent (sensory) Fibers- The Visceral afferent (sensory) Fibers- The Visceral afferent (sensory) Fibers– The Somatic efferent (motor) FibersThe Somatic efferent (motor) Fibers- The Visceral efferent (motor) Fibers- The Visceral efferent (motor) Fibers

Four Types of Fibers in Spinal Nerves– The Somatic afferent (sensory) FibersThe Somatic afferent (sensory) Fibers- The Visceral afferent (sensory) Fibers- The Visceral afferent (sensory) Fibers– The Somatic efferent (motor) FibersThe Somatic efferent (motor) Fibers- The Visceral 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 nerveThe lesser occipital nerve

The great auricular nerveThe great auricular nerve

The transverse nerve of neckThe transverse nerve of neck

The supraclavicular nervesThe supraclavicular nerves

• The Deep BranchesThe Deep Branches– The phrenic nerveThe phrenic nerve

The Brachial Plexus The Brachial Plexus (scalene fissure, axilla)(scalene fissure, axilla) formation:formation: root(C5 – T1) trunk division cordroot(C5 – T1) trunk division cord

branches and distributionbranches and distribution Brachial plexus : Brachial plexus : the long thoracic the long thoracic

the musculocutaneous nervethe musculocutaneous nerve

lateral cordlateral cord lateral pectoral nerve lateral pectoral nerve

the median nerve the median nerve

Medial cordMedial cord the ulnar nerve the ulnar nerve

medial pectoral nervemedial pectoral nerve

the radial nerve the radial nerve

Posterior cordPosterior cord the axillary nerve the axillary nerve

the thoracodorsal nervethe thoracodorsal nerve

the musculocutaneous n.the musculocutaneous n.

the axillary n.the axillary n. the long thoracic n.the long thoracic n.

medial pectoral n.medial pectoral n.

lateral pectoral n.lateral pectoral n.

median n.median n.

the ulnar n. the radialthe ulnar n. the radial n n. .

the thoracodorsal 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, an inability to extend the hand at the wrist

Radial Nerve

The Anterior Branches of the Thoracic Nerves

——Intercostal and subcostal nerve

The segmental distribution of the anterior branches of The segmental distribution of the anterior branches of the thoracic nervesthe thoracic nerves

T2: the sternal angle T8: the costal arch

T4: the nipple T10: the umbilicus

T6: the xiphoid processT12: the anterior superior iliac spin

The Lumbar Plexus• The formation of the lumbar plexus: The formation of the lumbar plexus:

TT12 12 (part)+L(part)+L1~31~3+L+L4 4 (part)(part)

The branches of the lumbar plexusThe branches of the lumbar plexus

The The iliohypogastriciliohypogastric nerve nerveThe The ilioinguinalilioinguinal nerve nerveThe The lateral femoral lateral femoral cutaneouscutaneous nerve nerveTheThe femoral femoral nerve nerveThe The obturatorobturator nerve nerveTheThe genitofemoral genitofemoral nervenerve

The Sacral Plexus

• The formation of the sacral plexusThe formation of the sacral plexus

The lumbosacral trunk(LThe lumbosacral trunk(L4~54~5)+S)+S1~51~5+Co+Co

The branches of The branches of the sacral plexusthe sacral plexus

The branches of the sacral plexusThe branches of the sacral plexus

–The superior gluteal n.The superior gluteal n.

–The inferior gluteal n.The inferior gluteal n.

–The pudendal n.The pudendal n.

The anal nervesThe anal nerves

The perineal nerveThe perineal nerve

The dorsal nerve of The dorsal nerve of

penis or clitorispenis or clitoris

- The posterior femoral - The posterior femoral

cutaneous n.cutaneous n.

The sciatic nerveThe sciatic nerve(Poplited fossa)(Poplited fossa)

•The tibial nerveThe tibial nerve•(hook-like foot)(hook-like foot)

•The common peronealThe common peroneal nervenerve(talipes equinovarus)(talipes equinovarus)

The superficial peronealThe superficial peroneal nervenerveThe deep peroneal nerveThe deep peroneal nerve

体表节段分布

The Cranial Nerves

脑神经

Names of cranial nervesThe cranial nerveⅠ. 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

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 Nerves1. Sensory nerves:

– carry somatic sensory information: • touch, pressure, vibration, temperature, and pain

2. Special sensory nerves:– carry sensations:

• smell, sight, hearing, balance3. 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.

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.

ciliary muscleciliary muscle

sphincter pupillae sphincter pupillae musclesmuscles

diplopiadiplopia

The The general visceral general visceral motor fibers motor fibers

The general somatic The general somatic motor fibersmotor fibers

Oculomotor nervesuperior obliquussuperior obliquus

Trochlear n.

Abducent n.

lateral rectuslateral rectus

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

Figure 14–21

The Trochlear Nerves (IV)

• Primary function: – motor (eye movements)

• Origin: mesencephalon• Pathway: superior orbital fissure of sphenoid• Destination: superior oblique muscle

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 )

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)Abducens nerve (VI)• enters the orbit through the superior orbital fissure.enters the orbit through the superior orbital fissure.

• Innervates the lateral rectusInnervates 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

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.

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]

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 ]

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 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]

Vestibular ganglion(SSA) ↘ ↗ Vestibular nuclei Internal acoustic meatus Cochlear ganglion (SSA) ↗ ↘ Cochlear nuclei

somatic sensory fibers

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 ( )ⅨComponents 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:

— 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:

— 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

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

Table 14-9 (1 of 2)

Summary: Cranial Nerves

Table 14-9 (2 of 2)

Summary: Cranial Nerves

The Cranial NervesThe 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。

Documents

The Nervous System