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