The cranial nerves

1. The definition of CNThe cranial nerves are the nerves which are attached to the brain.

CNI Olfactory nerve

CN Optic nerveⅡ

CN Oculomotor nerveⅢ

CN Trochlear nerve Ⅳ

CN Trigeminal nerveⅤ

CN Abducent nerveⅥ

CN Facial nerveⅦ

CN Vestibulocochlear nerveⅧ

CN Glossopharyngeal nerveⅨ

CN Vagus nerveⅩCN Accessory nerveⅪCN Hypoglossal nerveⅫ

2. The cranial nerves consist of 7 kinds of nervous fiber components

Structures innervated

SENSORY TYPE

genernal somatic skin,muscles, joints of the head,most mucous membrane of the oral and nasal cavity

special somatic retina; inner ear

genernal visceral cranial, thoracic, abdominal viscera

special visceral taste buds; olfactory region

Structures innervated

MOTOR TYPE

General somatic extraocular muscles; tongue muscles

General visceral parasympathetic ganglia for cranial,thoracic, and abdominal smooth muscles and glands

branchial (special viseral)

masticatory muscles; facial muscles;middle ear muscles; laryngeal and pharyngeal muscles; sternocleidomastoid , trapezius

2. The cranial nerves consist of 7 kinds of nervous fiber components

3. The classifications of cranial nerves

① The sensory nerves:

CNI, CNII, CNVIII

② The motor nerves:

CNIII, CN IV, CNVI, CNXI, CNXII

③ The mixed nerves:

CNV, CNVII, CNIX, CNX

The olfactory nerve (CNI)

The olfactory nerve (CNI)

Primary function: special visceral sensory (smell)

Origin: mucous membrane of the olfactory region of the nasal cavity

Passes through: cribriform foramina of ethmoid bone

Destination: olfactory bulb

The optic nerve (CNII)

The optic nerve is inclosed in three layers of coverings. These coverings and the spaces between them are continuous with those of the brain. So that, the meningitis may involve the eyes.

The optic nerve (CNII)

Primary function: special somatic sensory (vision)

Origin: retina of eye

Passes through: optic canal

Destination: diencephalons

The oculomotor nerve (CNIII)

General somatic motor fibers arise from the oculomotor nucleus

General visceral motor fibers arise from the accessory occulomotor nucleus

Superior branch: sup. rectus, levator palpebrae superioriis

Inferior branch: inf./med. rectus, inf. obliquus

Ciliary ganglion

The oculomotor nerve ( CNIII)

Primary function: motor, eye movements

Origin: midbrain

Passes through: sup. orbital fissure

Destination: general somatic motor— sup./inf./med. rectus, inf. obliquus, levator palpebrae superioris general visceral motor —pupillary sphincter, ciliary muscles

The trochlear nerve ( CNIV )

The trochlear nerve ( CNIV )

Primary function: motor, eye movements

Origin: midbrain

Passes through: sup. orbital fissure

Destination: sup. obliquus

The trigeminal nerve (CNV)

Two roots ：The special visceral efferent fibers arise from the motor nucleus of the trigeminal nerve and only take part in the third division of the trigeminal nerve.

The general somatic afferent fibers are made up of the central processes of neurons which are located in the trigeminal ganglion

Motor root

Sensory root

The trigeminal nerve (CNV)

Three divisions:

The ophthalmic nerve (CN 1)Ⅴ

The maxillary nerve (CN 2)Ⅴ

The mandibular nerve (CNⅤ3)

The trigeminal nerve (CNV )

ophthalmic n. branches: ① lacrimal n.

② frontal n.

③ nasocillary n.

It leaves the skull through the sup. orbital fissure

The trigeminal nerve (CNV )

maxillary n. branches:

① infraorbital n.

② pterygopalatine n.

③ sup. alveolar n.

It leaves the skull through the foramen rotundum

The trigeminal nerve (CNV )

mandibular n. branches: ①the nerves of masticatory muscles②buccal nerve③auriculotemporal nerve④inf. alveolar n.⑤lingual n.

It emerges through the foramen ovale

corda tympani:a. visceral motor fibers : sup. salivatory nucleus.b. visceral sensory fibers: nucleus of solitary tract

The trigeminal nerve (CNV )

Primary function: mixed ( sensory & motor) Origin:Ophthalmic nerve (sensory) —orbital structures, nasal cav

ity, skin of forehead..Maxillary nerve (sensory) —skin between the fissures of e

ye and mouth, upper teeth and gums..Mandibular nerve (mixed) —skin below the fissure of mout

h, lower teeth and gums(sensory); motor nuclei of pons(motor)

Passes through: Ophthalmic nerve —sup. orbital fissureMaxillary nerve —foramen rotundumMandibular nerve —foramen ovaleDestination: CNV1 , CNV2 and part of CNV3 to sensory n

uclei in brainstem; part of CNV3 innervates muscles of mastication

The abducent nerve (CNVI )

The abducent nerve (CNVI )

Primary function: motor, eye movements

Origin: pons

Passes through: sup. orbital fissure of sphenoid bone

Destination: lat. rectus