Download Cranial Nerves

Cranial Nerves




The name and the order
Ⅰ
Ⅱ
Ⅲ
Ⅳ
Ⅴ
Ⅵ
Ⅶ
Ⅷ
Ⅸ
Ⅹ
Ⅺ
Ⅻ
olfactory nerve
optic nerve
oculomotor nerve
trochlear nerve
trigeminal nerve
abducent nerve
facial nerve
vestibulocochlear nerve
glossopharyngeal nerve
vagus nerve
accessory nerve
hypoglossal nerve
The sites they attached to the brain
Ⅰ：telencephalon
Ⅱ：diencephalon
Ⅲ, Ⅳ: midbrain
Ⅴ-Ⅷ: pons
Ⅸ-Ⅻ: medulla oblongata
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)
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)
The types 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
Mnemonics
Some Say Marry Money But My Brother Says Big Brains Matter More
S=sensory
M=motor
B=both
Olfactory n.
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)
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.
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.
ganglion cells---optic nerve---optic canal---optic chiasma
Optic canal in
Sphenoid bone
Cranial Nerve III: Oculomotor n.
General somatic and visceral efferent fibers
• 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.
Superior orbital
fissure
in the sphenoid bone
Cranial Nerve IV: Trochlear n.
General somatic efferent (motor)
 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
Cranial Nerve IV: Trochlear n.
Cranial Nerve VI: Abducent n.
General somatic efferent
• 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
Cranial Nerve V: Trigeminal n.
General somatic afferent
Special visceral 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.
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 )
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.
Cranial Nerve VII: Facial n.
• 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.
General visceral efferent
Lacrimal and salivary gland
Special visceral efferent
Facial expression M
Special visceral afferent
taste
•General somatic afferent
external ear
Special visceral efferent
smoothing
drooping
Deeping
Failure in complete close
Lips can not be pursed
General visceral efferent
salivary glands
Lacrimal gland
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
cochlear nerve conduct auditory sense
central
process
Nucleus of
cochlear
cochlear
nerve
spiral
ganglion
peripheral
process
auditory
perceptive organ
(cortis)
（bipolar neuron）
Central
Peripheral
vestibular nerve conduct equilibratory sensation
Nucleus of
Vestibular
vestibular
central process
ganglion
vestibular nerve
peripheral
process
（bipolar neuron）
statoreceptor
（macula utriculi、macula
sacculi、crista ampullaris）
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)
Inferior salivatory nucleus
Ambiguus nucleus
auricular
ganglion
Solitary tract nucleus
stylopharyngeus
parotid gland
carotid glomus
carotid sinus
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
Branches in neck
Superior laryngeal n.
-Internal branch: laryngeal mocosa
above the fissure of glattis
-External branch: cricothyroid M
Superior laryngeal n
 Cervical cardiac branches
 Pharyngeal branches
 Auticular branch
Internal branch
External branch
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 canal
Hypoglossal nucleus——hypoglossal nerve
lingual muscle