Term
Olfactory Nerve
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Definition
CN # = I
Afferent component = SA, smell, taste, vision, hearing, balance afferents
Efferent component = NONE
Exit from skull =Cribriform plate of ethmoid bone
Function = Smell
LESION: Loss of smell (anosmia), injury to cribriform plate; congenital absence.
*end up synapsing with secondary neurons in olfactory bulbs |
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Term
Optic Nerve
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Definition
CN # = II
Afferent component = Smell taste, vision hearing, balance afferent
Efferent component = NONE
Exit from skull = Optic canal
Function = Vision
*return information to brain from photoreceptors in retina
LESION: Blindness/visual field abnormalities, loss of pupillary constriction. Direct trauam to orbit, disruption of optic pathway. |
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Term
Oculomotor nerve
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Definition
CN # = III
Afferent component = NONE
Efferent component = General somatic efferent, General visceral efferent
Exit from skull =Superior orbital fissure
Function = GSE: 1) levator palpaebrae superioris, 2) rectii muscle (except lateral), 3) inferior oblique muscles. GVE - innervates 1) sphincter pupillae for pupillary constriction 2) ciliary muscles for accomodation of the lens for near vision
*GVE fibers are parasympathetic! Accomodation for near vision, pupillary constriction
*LESION: Dilated pupil, ptosis, loss of normal pupillary reflex, eye moves down inferiorly and laterally. Caused by pressure from aneurysm from posterior communicating, posterior cerebral, or superior cerebellar artery, pressure from a herniating cerebral uncus, cavernous sinus mass, or thrombosis |
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Term
Trochlear Nerve
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Definition
CN # = IV
Afferent component = NONE
Efferent component = GSE
Exit from skull = superior orbital fissure
Function = Innervates superior oblique muscle
*The only cranial nerve to exit from posterior surface of brainstem
LESION: Inability to look down and in. Injury along course of nerve around brainstem; orbital fracture. |
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Term
Trigeminal Nerve
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Definition
CN # = V
Afferent component = GSA
Efferent component = Branchial efferent (motor innervation to skeletal muscles from pharyngeal arch mesoderm)
Exit from skull = see
Function = see
*Be - innervates temporalis, masseter, medial and lateral pterygoids, tensor tympani, tensor veli palantini, anterior blely of digastric, and mylohyoid muscles
LESION: Losso f sensation/pain in regions; loss of motored mastication. Problem typically in region of trigeminal ganglion. |
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Term
Ophthalmic Division
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Definition
CN # = V-1
Afferent component = GSA
Efferent component = Branchial efferent
Exit from skull = superior orbital fissure
Function = eyes, conjuctiva, orbital contents, nasal cavity, frontal sinus, ethmoid sinus, upper eyelid, dorsum of nose, anterior part of scalp |
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Term
Maxillary division
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Definition
CN # = V-2
Afferent component = GSA
Efferent component = BE
Exit from skull = foramen rotundum, enters pterygopalatine fossa
Function = dura in anterior and middle cranial fossae, nasopharynx, palate, nasal cavity, upper teeth, maxillary sinus, skin covering the side of hte nose, lower eyelid, cheek, upper lip |
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Mandibular division:
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Definition
CN # = V-3
Afferent component = GSA (general somatic afferent = perception of touch, pain temperature)
Efferent component = BE
Exit from skull = foramen ovale
Function = skin of lower face, cheek, lower lip, ear, external acoustic meatus, temporal fossa, anterior 2/3 of tongue, lower teeth, mastoid air cells, mucuous membranes of cheek, mandible, dura in middle cranial fossa
*once it leaves foramen ovale, unites with sensory component of mandibular nerve (V3) outside of skull; only division of trigeminal nerve htat contains a motor component (muscles of mastication (temporalis, massseter, medial/lateral pterygoids, tnesor tympani, tensor veli palatini, digastric anterior belly, and mylohyoid) |
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Term
Abducent Nerve
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Definition
CN # = VI
Afferent component = NONE
Efferent component = GSE
Exit from skull = Superior orbital fissure
Function = Innervates lateral rectus muscle
*arises from brainstem between pons and medulla, passes forward, enters/crosses cavernous sinus just interolateral to internal carotid artery
LESION: Inability to lateral eye movement. Example, brain lesion or cavernous sinus lesion extending onto the orbit. |
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Term
Facial nerve
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Definition
CN # = VII
Afferent component = GSA (perception of touch, pain, temperature), SA (smell, taste, vision, hearing, balance)
Efferent component = GVE, BE
Exit from skull = Internal acoustic meatus
Function = GSA - sensory from external acoustic meatus, skin posterior ear. SA - taste from anterior 2/3rd of tongue. GVE - motor innervates lacrimal gland, submandibular and sublingual salivary glands, and mucous membranes of nasal cavity, and hard and soft palates. BE - motor innervates muscesl of face (facial expression) and scalp derived from 2nd paryngeal arch, and stapedius, posteriro belly of digastric, stylohyoid muscles
Paralsysi fof faicla muscles below eye. Abnormal taste sensation of tongue, dry conjuctivae. Caused by damage to branches within the parotid gland. Injury to temporal bone; viral inflammation of nerve. Or brainstem injury. |
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Term
Vestibulocochlear nerve
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Definition
CN # = VIII
Afferent component = SA
Efferent component = NONE
Exit from skull = Internal acoustic meatus
Function = Vestibular division - balance, Cochlear division - hearing
*two divisions combine into single nerve seen in posterior cranial fossa within the substance of the petrous part of the temporal bone
LESION: Progressive unilateral hearing loss and tinnitus (ringing in ear). Example: tumor at cerebellopontine angle. |
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Term
Glossopharyngeal nerve
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Definition
CN # = IX
Afferent component = GVA, SA
Efferent component = GVE, BE
Exit from skull = Jugular foramen
Function = GVA - sensory from carotid body and sinus, posterior one-third of tongue, palatine tonsils, upper pharynx, and mucosa of middle ear and pharyngotympanic tube. SA - taste from posterior 1/3 of tongue. GVE - innervates parotid salivary gland. BE - innervates stylopharyngeus muscle.
*The glossopharyngeal nerve arises as several rootlets on the anterolateral surface of the upper medulla oblongata. The rootlets cross the posterior cranial fossa and enter jugular foramen; within foramen, merge to form glossopharyngeal nerve. WIthin or immediately outside the jugular foramen are two ganglia (superior/inferior ganglia), which contain the cell bodies of the sensory neurons in the glossopharyngeal nerve (IX).
LESION: Loss of taste to posteriro 1/3rd of tongue, sensation of soft palate. Due to brainstem lesion/penetrating neck injury. |
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Term
Tympanic Nerve
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Definition
| CN # = branching from glosspharyngeal nerve within or immediately outside jugular foramen, re-etners temporal bone, enters middle eary cavity, and partiicpates in formation of tympanic plexus. Also contributes GVE fibers, leave tympanic plexus in lesser petrosal nerve, small nerve that exits the tmeporal bone, descends through foramen ovale to exit the cranial cavity carrying pregnaglionic parasympathetic fibers to otic ganglion. |
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Vagus Nerve
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Definition
CN # = X
Afferent component = GSA, GVA, SA
Efferent component = GVE, BE
Exit from skull = Jugular foramen
Function = GSA - sensory from skin posterior to ear and external acoustic meatus, and dura in posterior cranial ossa. GVA - sensory from aortic body chemoreceptors and aortic arch baroreceptors, mucous membranes of pharynx, larynx, esophagus, bronchi, lungs, heart, and abdominal viscera of the foregut and midgut. SA - taste from epiglottis. GVE - innervates smooth muscle and glands in the pharynx, larynx, thoracic viscera, and abdominal viscrea of foregut and midgut. BE - innervates one tongue muscle (palatoglossus), muscles of soft palate (except tensor veli palatini), pharynx (except stylopharyngeus), and larynx
*Within or immediately outside the jugular foramen are two ganglia, sueprior/inferior ganglia, contain cell bodies of sensory neurons in vagus nerve
LESION: Soft palate deviation with deviation of uvula to the normal side; vocal cord paralysis. Due to brainstem lesion; penetrating neck injury. |
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Term
Accessory Nerve
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Definition
CN # = XI
Afferent component = NONE
Efferent component = BE
Exit from skull = Jugular foramen
Function = Innervates sternocleidomastoid and trapezius muscles
*Crouse: arise from motor neurons in upper five segments of cervical spinal cord. These fibers leave hte lateral surface, as they ascend, enter cranial cavity through foramen magnum. The accessory nerve (XI) continues through the posterior cranial fossa and exits through the jugular foramen.
LESION: paralysis of sternocleidomastoid and trapezius muscles. Ex) penetrating injury to hte posterior triangle of the neck. |
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Term
Hypoglossal nerve
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Definition
CN # = XII
Afferent component = NONE
Efferent component = GSE
Exit from skull = Hypoglossal canal
Function = Innervates hypoglossus, genioglossus, and styloglossus muscles and all intrinsic muscles of the tongue
LESION: Atrophy of tongue, speech disturbance. Penetrating injury to neck and skull base pathology
LESION: atrophy of ipsilateral muscles of tongue, and deviation towards affected side; speech disturbance. |
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