Cranial nerve V Trigeminal nerve Flashcards
First Initial: Special v. General
Special: Function only found in a cranial nerve
General: Function can be found in cranial or spinal nerve
Second Initial: visceral v Somatic
Visceral: target part of visceral system or a structure derived from specialized embryonic precursors called pharyngeal arches
Somatic: voluntary motor conrtrol, skeletal/striated muscle, also includes somatic sensory fibers
Third initial: Afferent v efferent
afferent brings sensory info to CNS efferent brings motor info away from CNS
Types of Afferent fibers
General Somatic Affternts, General Visceral Afferents, Special afferents
General somatic afferents
Convey sensations from skin muscles and joints (touch pressure heat cold)
General visceral afferent
convey senses from internal organs
Special Afferents
special sense of vision hearing balance taste smell
Types of efferent fibers
General Somatic Efferents, Special Visceral Efferent, General Visceral Efferent
General Somatic Efferent
Innervate striated muscle not derived from embryonic pharyngeal arches (like extraocular eye muscles, tongue)
Special Visceral Efferent
Innervate striated muscle with embryological origin from phayngeal arches (facial expression, mastication)
General Visceral Efferent
Autonomic fibers that innervate smooth muscle and glands
Which nuclei of trigenimal nerve V are General Somatic afferents?
Mesencephalic nucleus, Main/principal/chief sensory nucleus V, and Spinal trigeminal nucleus
Which nucleus of trigeminal nerve is a Special Visceral efferent?
Motor nucleus V
Semilunar ganglion, Gasserian ganglion
same as Trigeminal ganglion
V1
opthalmic neve
V2
Maxillary Nerve
V3
mandibular nerve
Spinal Trigeminal nucleus
receives pain temp and crude touch sensations from face
Main sensory nucleus
receives light touch and pressure info from face, and proprioceptive info
Motor nucleus V
SVE projects axons to muscles of mastication
What path does trigeminal nerve take from the brainstem to its targets?
From brainstem it courses anteriorly through middle cranial fossa where the trigeminal ganglion are on the floor of the middle cranial fossa. then it emerges as V1 V2 and V3, they leave the cranial cavity via openings in middle cranial fossa
Superior orbital fissure
V1 travels through here
foramen rotundum
V2 travels through here
Foramen ovale
V3 travels through here
Supraorbital nerve V1 distribution?
distributed in mucosa of frontal sinus, skin and conjunctiva of superior eyelid, skin and pericranium of anterolateral forehead and scalp to vertex
Supratrochlear nerve V1 distribution?
skin and conjunctiva of medial aspect of superior eyelid, skin and pericranium of anteromedial forehead
Lacrimal nerve V1 distribution?
Lacrimal gland secretomotor fibers, small area of skin and conjuntiva of lateral part of superior eyelid
Infratrochlear nerve V1 distribution?
distributed in skin lateral to root of nose, skin and conjunctiva of eyelids adj to medial canthus, lacrimal sac and lacrimal caruncle
External nasal nerve V1 distribution?
skin of nasal ala, vestibule and dorsum of nose including apex
Infraorbital nerve V2 distribution?
distributed in mucosa of maxillary sinus, premolar canine and incisor maxillary teeth, skin and conjunctiva of inferior eyelid, skin of cheek, lateral nose and anteroinferior nasal septum, skin and oral mucosa of superior lip.
Zygomaticofacial nerve V2 distribution?
distributed in skin on prominence of cheek
Zygomaticotemporal Nerve V2 distribution?
distributed on hairless skin anterior part of temporal fossa
Auriculotemporal nerve V3 distribution?
distritubed in skin anterior to auricle and posterior 2/3 of temporal region, skin of tragus and adjacent helix of auricle, skin of root of external acoustic meatus, and skin of superior tympanic membrane
Buccal Nerve V3 distribution?
Skin and oral mucosa of cheek, buccal gums adjacent to second and third molars
Mental Nerve V3 distribution?
skin of chin and skin of mucosa of inferior lip
Subdivisions in rostral caudal direction of Spinal trigeminal Nucleus
Pars Oralis, Pars Interpolaris, Pars Caudalis
Pars Oralis
located rostrally, extends from main sensory nucleus to pontomedullary junction
Pars Interpolaris
Middls position, extends from pontomedullary junction to level of obex (caudal end of fourth ventricle)
Pars Caudalis
located caudally, extends from obex to spinal cord (C2-C3) thought to be MAJOR synaptic site for pain temp and crude touch from face, organization described as onion like.May be involed in gingival and pulp innervation.
Organization of spinal trigeminal tract and spinal trigeminal nucleus
Ventral to dorsal organization. Fibers from V1(opthalmic nerve) are located ventrally. Fibers from V2(maxillary nerve) are located in middle portion. Fibers of V3 (mandibular nerve) are located dorsally.
Type of neuron in mesencephalic nucleus
pseudounipolar neurons
trigeminal lemniscus
part of touch/pressure pathway of face, where 2nd order touch/prop fibers join medial lemniscus in mid-pons.
How do 2nd order neurons that receive A-beta info from oral cavity get to the brain?
They do not cross, they come in from midbrain to mesenchephalic nucleus to main sensory nucleus V then to VPM then to postcentral gyrus. The travel through dorsal trigeminal tract, in dorsomedial brainstem tegmentum (not in medial lemniscus) they travel along taste pathway which is also ipsilateral
Three regions of Main sensory nuceus
same dorsal ventral organization as spinal trigeminal nucleus and tract. Ventral receives V1, Mid-region receives V2, Dorsal receives V3
Intraoral regions of main sensory nucleus
represented in dorsomedial region and project ipsilaterally to VPM
Wallenberg’s Syndrome
Lateral medullary syndrome, caused by ischemia in territory of vertebral artery and/or PICA. Usually involves spinal trigeminal nucleus and tract, spinothalamic tract, descending sympathetic fibers
What will a lesion in left lateral medulla cause?
decrease pain and temp sensation of ipsilateral side of face bc of damage to second order neurons in spinal trigeminal nucleus/tract. And contralateral damage to spinothalamic tract
Horner’s Syndrome
absence of sympathetic stimulated functions on ipsilateral side of head, includes Ptosis (drooping of superior eyelid) Miosis (constriction of pupil) Anhydrosis (absence of sweating) redness of skin (vasodilation)
Which nucleus follows the S-1 path?
Main sensory nucleus V
which nucleus projects to cerebellum
Spinal Trigeminal nucleus
Which nucleus mediates jaw-jerk reflex?
Motor nucleus V
Why doesn’t unilateral lesion of corticobulbar tract fibers produce dramatic weakness in mastication?
CN-V motor nucleus receives bilateral input from corticobulbar tract fibers
