NAS WK6 - CRANIAL NERVES Flashcards
1
Q
MODALITIES OF AFFERENT/SENSORY NERVES
A
- GSS (general sensation) for touch, pain, temp
- SSS (special sensation)
for vision, smell, hearing - GVS (general visceral sensory) for innervation of blood vessels
2
Q
MODALITIES OF EFFERENT/MOTOR NERVES
A
- GSE - somatic (supplies - -GVE - autonomic (supply smooth & cardiac muscle)
3
Q
CNI
A
- NAME - olfactory nerve
- JOB - smell
- TRAVEL - olfactory receptor cells –> olfactory nerves in cribriform plate of ethmoid bone –> olfactory bulb –> olfactory tract (carry info about smell to olfactory cortex)
- MODALITY - sensory(SVS)
- ORIGIN - cerebrum (brain)
- TEST- tested by giving odours & asking to identify
- DAMAGE - leads to anosmia (smell loss) or distorted smell
4
Q
CNII
A
- NAME - optic nerve
- JOB - vision
- MODALITY - sensory (SSS)
- EXIT - optic tract
- ORIGIN - cerebrum
- TRAVEL - nerve carries signals from axons of retinal ganglia cells -> axons come together & leave eye at optic disc to form optic nerve -> goes to optic chiasm -> optic nerve fibres carrying info from side closest to nose cross over but those from near temple stay -> nerve fibres leave optic chiasm and are known as optic tract
- DAMAGE - (before optic chiasm = blindness in eye supplied by that optic nerve) (at optic chiasm = damage to lateral field of vision of both eyes) (at optic tract = 1/2 of visual field lost in both eyes e.g. left of both eyes)
LOOK AT CRANIAL NERVE SHEET
5
Q
NERVES OF OCULOMOTION
A
- nerves 3,4 & 6 (innervate extraocular muscles that move the eye)
- all exit at superior orbital fissure
6
Q
CNIII
A
- NAME - oculomotor nerve
- JOB - supplies 4/6 extraocular muscles that move eye & levator palpebra superioris muscle (moves eyelid) (GSM) & ciliary ganglion (pupillary constriction) (GVM)
- ORIGIN - midbrain
- MODALITY - motor (GSM & GVM)
- EXIT - superior orbital fissure
- TRAVEL - oculomotor nucleus in midbrain –> eye orbit (split into branches that supply dif. extraocular muscles on the way)
- DAMAGE - nerve damage in same side of eye as damage
7
Q
CNIV
A
- NAME - trochlear
- JOB - supplies superior oblique (SO)(eye moves down & out)
- EXIT - superior orbital fissure
- MODALITY - motor (GSM)
- ORIGIN - midbrain
- TRAVEL - start at trochlear nucleus in midbrain -> nerve fibres cross over to other side of brainstem before leaving brainstem in junction between midbrain & pons (posterior surface of brainstem)
- DAMAGE - leads to eye deviates upwards & diplopia (as no longer opposing force from SO so opposing muscle (IO) is weakened in surgery)
8
Q
CNV
A
- NAME - trigeminal
- DIVISIONS - ophthalmic (sensory), maxillary (sensory) & mandibular (sensory and also contains motor fibres which innervate the muscles of mastication (chewing) & tensor tympani (dampens loud sounds) & tensor veli palatini (equalises pressure)
- ORIGIN - pons (in hindbrain)
- NUCLEI (3 sensory & 1 motor)
- main sensory nucleus receives info from head on touch & proprioception
- trigeminal sensory nucleus receives info on pain & temp
- mesecephalic sensory nucleus receives proprioceptive info from jaw & teeth to prevent damage while chewing
- motor nucleus controls muscles for chewing
- DAMAGE - causes decreased sensation, weakening of mastication muscles, trigeminal neuralgia (short, intense periods of facial pain)
9
Q
CNVI
A
- NAME - abducens nerve
- JOB- supplies lateral rectus muscle (extraocular muscle of eye that moves eye laterally towards side of head) on same side of head
- MODALITY - motor
- ORIGIN - pons-medulla junction
- TRAVEL - abducens nerve fibres exit brainstem at pons-medulla junction & supply lateral rectus muscle on same side of head
- some neurones from abducens nucleus also control medial rectus muscle (moves eye inwards)
- DAMAGE - causes diplopia & esotropia (cross-eyed) (as loss of abducens nerve & unopposed function of medial rectus)
10
Q
CNVII
A
- NAME - facial nerve
- JOB - receive sensory info from outer ear & taste buds on anterior 2/3 of tongue
- supplies most major glands in head e.g. tear, paranasal sinus
- ORIGIN - pons-medulla junction
- part that supplies glands originates in superior salivatory nucleus in pons
- motor part originates in facial motor nucleus in pons
- MODALITY - motor & sensory
- DAMAGE - paralysis of muscle of facial expression on side of damaged nerve supply so mouth droops & patient can’t close eyes
11
Q
CNVIII
A
- NAME - vestibulocochlear
- JOB - hearing & balance
- MODALITY - sensory
- ORIGIN - pons-medulla junction
- TRAVEL - hair cells relay auditory signals to cochlear portion of nerve & nerve travels to dorsal & ventral cochlear nuclei (found at junction) & they send auditory info to brain
- vestibular apparatus in hair cells receive stimulation & signal travels to vestibular nuclei in pons & medulla & from there, neurones leave each of these nuclei to project to areas in brain
- DAMAGE - causes damage to hearing & vestibular functions (hearing loss, tinnitus, dizziness, loss of balance)
12
Q
CNIX
A
- NAME - glossopharyngeal nerve
- JOB - associated with tongue & pharynx/throat (sensory info from posterior 1/3 of tongue, upper pharynx, tonsils, outer ear, eardrum & from carotid body & sinus)
- ORIGIN - medulla oblongata
- END - jugular foramen
- MODALITY - sensory & motor
- DAMAGE - causes taste loss from posterior 1/3 of tongue, trouble swallowing, decreased sensation on back of tongue, diminished gag reflex, glossopharyngeal neuralgia (brief intense pain in tongue)
- TRAVEL - innervates parotid gland (salivary gland)
13
Q
CNX
A
- NAME - vagus nerve
- JOB - carries info on pain, touch, temp from throat, ear & controls muscles in pharynx that control speaking & swallowing
- innervates heart, laryngopharynx, larynx, GI tract
- parasympathetic fibres originate in dorsal vagal motor nucleus but some originate in nucleus ambiguous (if heart)
- MODALITY - sensory & motor
- ORIGIN - medulla oblongata
- END - jugular foramen
- DAMAGE - leads to hoarse voice, difficulty swallowing, deficient gag reflex
14
Q
CNXI
A
- NAME - accessory nerve
- JOB - motor nerve that supplies sternocleidomastoid (muscle that turns head to side & bend neck up or side) & trapezius muscle (movement of neck & scapula)
- spinal root originates from spinal cord & cranial root from medulla & the spinal root joins the cranial root & they travel together as they exit skull but then cranial portion travels with vagus nerve while spinal root travels to sternocleidomastoid & trapezius muscles
- ORIGIN - medulla oblongata
- END - jugular foramen
- MODALITY - motor
- DAMAGE - weakness or paralysis of sternocleidomastoid or trapezius muscles & patient may experience shoulder & neck pain & fatigue (as muscles not used to supporting them)
- trapezius dysfunction can lead to winged scapula
15
Q
CNXII
A
- NAME - hypoglossal nerve
- JOB - supplies intrinsic (control shape) & extrinsic (move tongue) tongue muscles
- MODALITY - motor
- TRAVEL - fibres leave hypoglossal nuclei (in medulla) on each side of brain stem & descend to travel to same side of tongue to stimulate from below
- DAMAGE - tongue weakness, deviation of tongue to side of damaged nerve, speech problems
