cranial nerve vi: abducens fibers leave the pons and enter the orbit via the superior orbital...

Cranial Nerve VI: Abducens

Fibers leave the 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 abducens)

Abducens

Oculamotor paralysis

Abducent nerve injury

Trigeminal nerve

The largest cranial nerve Mixed cranial nerve Has 4 nuclei:

1. Main sensory nucleus

2. Spinal nucleus

3. Mesencephalic nucleus

4. Motor nucleus

Cranial Nerve V: Trigeminal

Trigeminal nerveComponents of fibers SVE fibers: originate from motor nucleus of

trigeminal nerve, and supply masticatory muscles, tensor tympani, tensor veli palatini, mylohyoid and digasteric(anterior bellly)

GSA 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

Branches Ophthalmic nerve ( 1, sensory) leave the Ⅴ

skull through the superior orbital fissure, to enter orbital cavity

Branches

– Frontal nerve• Supratrochlear nerve

• Supraorbital nerve

– Lacrimal nerve

– Nasociliary nerve

Distribution: carries sensory information from: the scalp and forehead the upper eyelid, the conjunctiva

and cornea of the eye the nose (including the tip of the

nose, except alae nasi), the nasal mucosa, the frontal sinuses

parts of the meninges (the dura and blood vessels).

Maxillary nerve ( 2, sensory)Ⅴ

Leave skull through foramen rotundum

Branches– Infraorbital nerve

– Zygomatic nerve

– Superior alveolar nerve

– Pterygopalatine nerve

Distribution: carries sensory information from : the lower eyelid cheek the nares and upper lip, the upper

teeth and gums, the nasal mucosa the palate and roof of the

pharynx, the maxillary, ethmoid and sphenoid sinuses

parts of the meninges.

Mandibular nerve ( 3, mixed)Ⅴ Leave the skull through the foramen

ovale to enter the infratemporal fossa

Branches– Auriculotemporal nerve 耳– Buccal nerve

– Lingual nerve

– Inferior alveolar nerve

– Nerve of masticatory muscles

Distribution: Sensation from cerebral dura

mater Teeth and gum of lower jaw Mucosa of floor of mouth Anterior 2/3 of tongue Skin of auricular and temporal

regions and below the mouth Motor to masticatory muscles,

mylohyoid, and anterior belly of digastric

Facial nerve ( )Ⅶ

Mixed cranial nerveHas 3 nuclei:

1. Main motor nucleus

2. Parasympathetic nuclei( superior salivatory and lacrimal nucleus)

3. Sensory nucleus

Facial nerve ( )ⅦComponents of fibers SVE fibers originate from nucleus of facial nerve, and supply facial

muscles, auricular muscles, stapedius, posterior belly of digasteric and

the stylohyoid muscles

GVE fibers derived from superior salivatory nucleus and relayed in

pterygopalatine ganglion and submandibular ganglion. The

postganglionic fibers supply lacrimal, submandibular and sublingual

glands

SVA fiber from taste buds of anterior two-thirds of tongue which cell

bodies are in the geniculate ganglion of the facial nerve and end by

synapsing with cells of nucleus of solitary tract

GSA fibers from skin of external ear

Course: leaves skull

through internal acoustic

meatus, facial canal and

stylomastoid foramen, it

then enters parotid gland

where it divides into five

branches which supply

facial muscles

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

and sublingual glands

Branches outside of facial canal Temporal Zygomatic Buccal Marginal mandibular Cervical

Cranial Nerve VII: Facial

Figure VII from Table 13.2

Cranial Nerve VIII: Vestibulocochlear

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

Vestibular nerve

Conduct impulses from saccule and utricle and semicircular canal

Vestibular ganglion in internal acoustic meatus

Enter vestibular nuclear complexEfferent fibers pass to cerebellum, spinal

cord, and MLF

Cochlear nerve

Conduct impulses from organ of Corti in cochlea

spiral ganglia in the cochleaEnter cochlear nucleiEnd in trapezoid body lateral leminiscus

inferior colliculus MGB auditory cortex through acoustic radiation

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

Cranial Nerve VIII: Vestibulocochlear

Figure VIII from Table 13.2

Cranial Nerve IX: Glossopharyngeal

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

Nerve IX is a mixed nerve with motor and sensory functions

Motor – innervates part of the tongue and pharynx, and provides motor fibers to the parotid salivary gland

Sensory – fibers conduct taste and general sensory impulses from the tongue and pharynx

Has 3 main nuclei:1. Main motor nucleus( stylopharyngeus

muscle)2. Sensory nucleus 3. Parasympathetic nucleus( inferior salivatory

nucleus)

CN IX: Glossopharyngeal Nerve

N. ambiguus

Motor nucleus for CN IX, X & XI

Stylopharyngeus (lifts pharynx)

N. solitariousSensory nucleus for CN VII, IX, X

Posterior 1/3 of the tongue

Inf. salivatory nucleusParotid gland, parasympathetic

Spinal trigeminal tract

CN V, VII, IX, X

Sensation behind ear

Glossopharyngeal nerve ( )ⅨComponents of fibers SVE fibers: originate from nucleus ambiguus, and supply

stylopharygeus GVE fibers: arise from inferior salivatory nucleus and ralyed in

otic ganglion, the postganglionic fibers supply parotid gland SVA 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

GVA fibers: visceral sensation from mucosa of posterior third of tongue, pharynx, auditory tube and tympanic cavity, carotid sinus, and end by synapsing with cells of nucleus of solitary tract

GSA fibers: sensation from skin of posterior surface of auricle

Course: leaves the skull via jugular foramen

Branches Lingual branches : to taste buds and mucosa of posterior third of tongue Pharyngeal branches : take part in forming the pharyngeal plexus Tympanic nerve : GVE fibers via tympanic and lesser petrosal nerves to

otic ganglion, with postganglionic fibers via auriculotemporal ( 3) to Ⅴparotid gland

Carotid sinus branch : innervations to both carotid sinus and glomus Others: tonsillar and stylophayngeal branches

Otic ganglion : situated just below foramen ovale

Cranial Nerve IX: Glossopharyngeal

Figure IX from Table 13.2

Cranial Nerve X: Vagus

The only cranial nerve that extends beyond the head and neck

Fibers emerge from the medulla via the jugular foramen

The vagus is a mixed nerve Most motor fibers are parasympathetic fibers to the

heart, lungs, and visceral organs Its sensory function is in taste

Has 3 main nuclei:1. Main motor nucleus( constrictors of the

pharynx and intrinsic muscles of the larynx)2. Sensory nucleus 3. Parasympathetic nucleus( dorsal nucleus of

vagus)

Vagus nerve ( )Ⅹcomponents of fibers 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

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

SVA: taste sensation

CN X: Vagus Nerve

N. ambiguus

Motor nucleus for CN IX, X & XI

Pharynx Larynx

N. solitariousSensory nucleus for CN VII, IX, X

Taste, epiglottis Cardiorespiratory

Dorsal motor nucleus of XParasympathetic, preganglionic

Spinal trigeminal tract

CN V, VII, IX, X

Ear

“Wanderer”

Cranial Nerve X: Vagus

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 on right side of trachea

Travels downward posterior to right brachiocephalic vein and superior vena cava

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, posterior to left brachiocephalic vein

Crosses aortic arch where left recurrent laryngeal nerve branches off

Passes posterior to left lung root Forms anterior esophageal plexus Forms anterior vagal trunk at esophageal hiatus

where it leaves thorax and passes into abdominal cavity , then divides into anterior gastric and hepatic branches

Cranial Nerve XI: Accessory 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

Primarily a motor nerve– Supplies fibers to the larynx, pharynx, and soft palate– Innervates the trapezius and sternocleidomastoid,

which move the head and neck

Cranial Nerve XI: Accessory

Figure XI from Table 13.2

Cranial Nerve XII: Hypoglossal

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(except palatoglossus)

GSE fibers

Cranial Nerves of the Medulla

Vestibular nucleiCN XII

Cranial Nerve XII: Hypoglossal

Figure XII from Table 13.2

Nerve injury

Trigeminal neuralgiaFacial nerve lesion(pells palsy)Vestibulocochlear nerve injuryGlossopharyngeal nerve injuryVagus nerve injuryAccessory nerve injuryHypoglossal nerve injury