cranial nerves - tongji...

Cranial Nerves

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

The name and the order

Ⅱ：diencephalon

Ⅲ, Ⅳ: midbrain

Ⅴ-Ⅷ: pons

The sites they attached to the brain

Ⅸ-Ⅻ: medulla oblongata

Ⅰ：telencephalon

general somatic efferent fiber (GSE): striated muscles involved in eye (Ⅲ , Ⅳ、Ⅵ ) and tongue (Ⅻ)

general visceral efferent fiber (GVE): preganglionic parasympathetic fiber travel within Ⅲ , Ⅶ, Ⅸ , Ⅹ

special visceral efferent fiber (SVE): striated muscles derived from the branchial arches involved in chewing (Ⅴ), making facial expressions (Ⅶ ), swallowing (Ⅸ、Ⅹ), producing vocal sounds (Ⅹ) and turning the head (Ⅺ)

Seven functional components of the

cranial nerves

general somatic efferent fiber (GSE): striated muscles involved in eye (Ⅲ , Ⅳ、Ⅵ ) and tongue (Ⅻ) general visceral efferent fiber (GVE): preganglionic parasympathetic fiber travel within Ⅲ , Ⅶ, Ⅸ , Ⅹ

special visceral efferent fiber (SVE): striated muscles derived from the branchial arches involved in chewing (Ⅴ), making facial expressions (Ⅶ ), swallowing (Ⅸ、Ⅹ), producing vocal sounds (Ⅹ) and turning the head (Ⅺ)

general somatic afferent fiber (GSA): sensation from skin, mucous membrane travel within Ⅴ, Ⅶ, Ⅸ, Ⅹ

general visceral afferent fiber (GVA): sensation from all viscera Ⅸ, Ⅹ

special visceral afferent fiber (SVA): smell (Ⅰ) and taste (Ⅶ, Ⅸ, X)

special somatic afferent fiber (SSA): visual(Ⅱ), hearing and equilibrium (Ⅷ)

Seven functional components of the

cranial nerves

Ⅰ, Ⅱ and Ⅷ are purely sensory

Ⅲ, Ⅳ, Ⅵ, Ⅺ and Ⅻ are purely motor;

Ⅲ, Ⅳ, Ⅵ control eye movement

Ⅺ control sternocleidomastoid and trapeziums;

Ⅻ control muscles of tongue

Ⅴ、Ⅶ、Ⅸ、Ⅹ are mixed nerves

Ⅲ 、 Ⅶ、Ⅸ、Ⅹ carry parasympathetic fibers

The types of the cranial nerves

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S=sensory

M=motor

B=both

Mnemonics

Olfactory n.

Arises from the olfactory epithelium (superior nasal

conchae and septum)

Passes through the cribriform plate of the

ethmoid bone

Carrying afferent impulses for the sense of smell (special visceral afferent)

Olfactory n.

fascicles emerging

through the

cribriform foramina

Anosmia (absence of sense of smell):

head trauma, Parkinson’s disease, virus infection, frontal lobe

tumors

Cranial Nerve II: Optic n.

• Arises from the retina of the eye

• Optic nerves pass through the optic canals

and converge at the optic chiasm

• They continue to the thalamus where they

synapse (lateral geniculate bodies )

• From there, the optic radiation fibers run to

the visual cortex

• Carrying afferent impulses for vision (special

somatic afferents fiber)

Cranial Nerve II: Optic n.

Cranial Nerve II: Optic n.

ganglion cells---optic nerve---optic canal---optic chiasma

Optic canal in

Sphenoid bone

• GSE extend from nucleus of oculomotor N. in midbrain, pass through the superior orbital fissure, and goes to the extra ocular muscles

(levator palpebrae, superior rectus, inferior rectus, inferior oblique, medial rectus) except two (superior oblique and lateral rectus).

• GVE extend from accessory nucleus of

oculomortor N. in midbrain, and goes to ciliary

muscle and sphincter pupillae (parasympathic)

via ciliary ganglia.

General somatic and visceral efferent fibers

Cranial Nerve III: Oculomotor n.

Superior orbital

fissure

in the sphenoid bone

Come from the nucleus of trochlear N. in the

midbrain (The only nerve which attached to the dorsal aspect of

the brain stem)

Pass through superior orbital fissure

Innervate the superior oblique M. (move the eye ball

medially and downward )

Damage it may cause diplopia when try to reading or

walking down stairs

General somatic efferent (motor)

Cranial Nerve IV: Trochlear n.

Cranial Nerve IV: Trochlear n.

Cranial Nerve VI: Abducent n.

• Fibers leave the nucleus of abducent in pons and enter the

orbit via the superior orbital fissure

• Primarily a motor nerve innervating the lateral rectus

muscle (abducts the eye; thus the name abducent)

• Damage it will cause the medial strabismus

General somatic efferent

• Composed of three divisions

– Ophthalmic (V1)

– Maxillary (V2)

– Mandibular (V3)

• Sensory fibers run from the face to the pons via the superior

orbital fissure (V1), the foramen rotundum (V2), and the

foramen ovale (V3), conveys sensory impulses from various

areas of the face and head.

• Supplies motor fibers for mastication

Cranial Nerve V: Trigeminal n.

General somatic afferent

Special visceral efferent

The trigeminal ganglion

is locates in the floor of

the middle cranial fossa,

on the bony depression

of petrous temporal bone,

has three braches

(TG is corresponds to the

dorsal root ganglion of the

spinal nerve )

Cranial Nerve V: Trigeminal n.

Ophthalmic N. (V1)

Divided into 3 branches:

The frontal N.

The lacrimal N.

The nasociliary N.

Function: the touch, temp and pain

sensations from:

anterior half of the scalp, skin of

forehead, upper eyelid , surface of

the eyeball, lacrimal gland, side of

nose, upper mucosa of the nasal

cavity.

Maxillary Nerve (V2)

Divided into 4 branches:

Infraorbital N.

zygomatic N.

superior alveolar N. pterygopalatine N.

Function: sensory from

Lower eyelid, lateral and

inferior mucosa of the

nasal cavity, palate and

portions of the pharynx,

teeth and gums of the upper jaw, upper lip.

Mandibular Nerve (V3)

5 branches:

Auriculotemporal N.

Buccal N.

Lingual N.

Inferior alveolar N. Nerves for masticatory muscles

Function:

Sensory: Teeth and gums of the lower jaw, anterior two-thirds of

the tongue (not taste), mucosa of

the mouth, auricle of the ear, low

part of the face

Motor: Masticatory muscle

(masseter, tempolis)

muscle of mastication:

lateral pterygoids,msseter,temporalis,mylohyoid,

digastric mucsle

Trigeminal neuralgia- One of the most excruciating pain known, caused by inflammation

of nerve.

• Fibers leave the pons, travel through the internal acoustic meatus,

and emerge through the stylomastoid foramen to the lateral aspect

of the face

• Motor functions include:

– Facial expression (Special visceral efferent )

– Transmit parasympathetic impulses to lacrimal and salivary

glands (submandibular and sublingual glands)(General visceral

efferent)

• Sensory functions:

Taste from taste buds of anterior two-thirds of the tongue (Special

visceral afferent)

From the skin of external ear (General somatic afferent )

Cranial Nerve VII: Facial n.

Cranial Nerve VII: Facial n.

General visceral efferent

Lacrimal and salivary gland

Special visceral afferent

taste

•General somatic afferent

external ear

Special visceral efferent

Facial expression M

Special visceral efferent

smoothing

drooping

Deeping

Failure in complete close

Lips can not be pursed

General visceral efferent

Lacrimal gland salivary glands

Sending out one branch for innverating tensor tympani muschle

Special visceral afferent

Loss of parasympathetic

General somatic affferent

Cranial Nerve VIII: Vestibulocochlear n.

• Fibers arise from the hearing and equilibrium

apparatus of the inner ear, pass through the

internal acoustic meatus, and enter the

brainstem at the pons-medulla border

• Two divisions – cochlear (hearing) and

vestibular (balance)

• Functions are solely sensory – equilibrium

and hearing

Cranial Nerve VIII: Vestibulocochlear n.

• Fibers arise from the hearing and equilibrium

apparatus of the inner ear, pass through the

internal acoustic meatus, and enter the

brainstem at the pons-medulla border

• Two divisions – cochlear (hearing) and

vestibular (balance)

• Functions are solely sensory – equilibrium

and hearing

Nucleus of

cochlear cochlear nerve

central process spiral

ganglion

peripheral

process auditory perceptive organ (cortis)

（bipolar neuron）

vestibular nerve conduct equilibratory sensation

Nucleus of

Vestibular

vestibular nerve

central process statoreceptor

peripheral process vestibular

ganglion

（bipolar neuron） （macula utriculi、macula sacculi、crista ampullaris）

cochlear nerve conduct auditory sense

Central Peripheral

Cranial Nerve VIII: Vestibulocochlear n.

Damage: cause tinnitus (ringing or buzzing in ear), vertigo

(dizziness, loss of balance) or impairment or loss of hearing

Cranial Nerve IX: Glossopharyngeal n.

• Fibers emerge from the medulla, leave the skull via the jugular foramen, and run to the throat

• A mixed nerve with motor and sensory functions

• Special visceral efferent fiber: stylopharyngeus muscle

• General visceral efferent fiber: parotid gland

• General visceral afferent fiber: normal sensation from posterior 1/3 of the tongue; carotid glomus and carotid sinus

• Special visceral afferent fiber: taste from posterior 1/3 of the tongue

Cranial Nerve IX: Glossopharyngeal n.

• Fibers emerge from the medulla, leave the skull via the jugular foramen, and run to the throat

• A mixed nerve with motor and sensory functions

• Special visceral efferent fiber: stylopharyngeus muscle

• General visceral efferent fiber: parotid gland

• General visceral afferent fiber: normal sensation from posterior 1/3 of the tongue; carotid glomus and carotid sinus

• Special visceral afferent fiber: taste from posterior 1/3 of the tongue

• pharyngeal branch→stylopharyngeus

• tympanic branch→lesser petrosal nerve otic ganglion parotid

gland

• lingual branch→ posterior 1/3 tongue to transmit general visceral

sensory and taste sense

• carotid sinus branch→carotid glomus and carotid sinus (chemoreceptor

and baroreceptors, which concerned with reflex control of respiration, blood pressure

and heart rate)

stylopharyngeus

parotid gland

carotid glomus

carotid sinus

auricular

ganglion

Ambiguus nucleus

Inferior salivatory nucleus

Solitary tract nucleus

Cranial Nerve X: Vagus n.

• The only cranial nerve that extends beyond the head and neck

• Fibers emerge from the medulla via the jugular foramen

• 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

• SVE fibers: originate from ambiguus, to muscles of pharynx and larynx

• GVA fibers: carry impulse from viscera in neck, thoracic and abdominal cavity to nucleus of solitary tract (left colic flexure)

• GSA fiber: sensation from auricle, external acoustic meatus and cerebral dura mater

• SVA fiber: taste from the epiglottis

• Paralysis leads to hoarseness

• Total destruction incompatible with life

Cranial Nerve X: Vagus n.

Course • Exits the skull from jugular foramen

• Descends in the neck in carotid sheath

between internal (or common) carotid artery

and internal jugular vein

Right vagus nerve

• Enter thoracic inlet

• Passes posterior to right lung root

• Forms posterior esophageal plexus

• Forms posterior vagal trunk at esophageal hiatus

where it leaves thorax and passes into

abdominal cavity, then divides into posterior gastric

and celiac branches

Left vagus nerve

• Enter thoracic inlet between left common

carotid and left subclavian arteries

• Crosses aortic arch where left recurrent

laryngeal nerve branches off

• Forms anterior esophageal plexus, give

branches to lung.

• Forms anterior vagal trunk at esophageal

hiatus where it leaves thorax and passes

into abdominal cavity, then divides into

anterior gastric and hepatic branches

Superior laryngeal n.

External branch

Internal branch

Superior laryngeal n.

-Internal branch: laryngeal mocosa

above the fissure of glattis

-External branch: cricothyroid M

Cervical cardiac branches

Pharyngeal branches

Auticular branch

Branches in neck

Branches in thorax

• Recurrent laryngeal nerves

– Right one hooks around right

subclavian artery, left one hooks

aortic arch

– Both ascend in tracheo-esophageal

groove

– Nerves enter larynx posterior to

cricothyroid joint, the nerve is now

called inferior laryngeal nerve

– Innervations: laryngeal mucosa below

fissure of glottis , all laryngeal

muscles except cricothyroid

Branches in abdomen

• Anterior and posterior gastric branches

– Run close to lesser curvature and innervate anterior and posterior surfaces of stomach

– As far as pyloric antrum 幽门窦 to form the digits of a crow’s foot to supply pyloric part

• Hepatic branches: join hepatic plexus and then supply liver and gallbladder

• 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

Cranial Nerve XI: Accessory n.

• Formed from a cranial root emerging from

the medulla and a spinal root arising from

the superior region of the spinal cord.

• The spinal root passes upward into the

cranium via the foramen magnum.

• The accessory nerve leaves the cranium via

the jugular foramen.

• Special visceral efferent

– Innervates the trapezius and sternocleidomastoid,

which move the head and neck

Cranial Nerve XI: Accessory n. • ambiguous nucleus→ cranial roots→ enter into vagus nerve→ laryngeal muscle

•accessory nucleus→ spinal roots→ sternomastoid , trapezius

Cranial Nerve XII: Hypoglossal n.

• Fibers arise from the medulla and exit the

skull via the hypoglossal canal

• Innervates both extrinsic and intrinsic

muscles of the tongue, which contribute to

swallowing and speech

• If damaged, difficulties in speech and

swallowing; inability to protrude tongue

Cranial Nerve XII: Hypoglossal n.

Hypoglossal nucleus——hypoglossal nerve hypoglossal canal

lingual muscle