Anatomy 4 Flashcards
which cranial nerves have parasympathetic function?
oculomotor
facial
glossopharyngeal
vagus
cranial nerve passes through which 3 areas during its course and what can go wrong at each level?
CNS - brainstem stroke intracranial - intracranial tumour extracranial - extracranial trauma (e.g orbital injury) can also have a base of skull fracture
what 2 nerves come off the midbrain?
3 and 4
what nerves come off pons?
trigeminal
what nerves come off medulla?
glossopharyngeal
vagus
hypoglossal
what runs through optic canal>
optic nerve
optic artery
function of olfactory nerve?
only modality is smell (special sensory)
describe the course of the olfactory nerve
olfactory nerves sit in the olfactory mucosa in the nasal cavity, exposed to the air
nerves go up through the cribiform plate of the ethmoid bone and enter the anterior cranial fossa
olfactory nerves then synapse in olfactory bulb
nerves then pass down olfactory tract to cortical areas in the brain
only function of optic nerve?
vision (special sensory)
course of optic nerve?
neurons leave retina and travel posteriorly via the optic nerve from the posterior hemisphere of eye through the orbit
enters the middle cranial fossa via the optic canal
travels around pituitary stalk to optic chiasm to form the optic tract
connect with CNS via thalamus then diencephalon
how can damage occur to optic nerve?
optic nerve can be compressed in the optic canal retinal artery (supply to optic nerve) can be disrupted or compressed in optic canal
how can olfactory nerve be tested?
ask patient to smell a familiar smell while covering the contralateral nostril
how can optic nerve be tested?
acuity colour fields reflexes fundoscopy
function of oculomotor nerve?
eye movement (motor) pupil constriction (parasympathetic)
course of oculomotor?
leaves CNS at midbrain (mesencephalon)
travels towards the orbit in the lateral wall of the cavernous sinus
exits the cranium in the superior orbital fissure
passes through SOF into the orbit and supplies all extraocular eye muscles apart from 2
parasympathetic fibres synapse in ciliary ganglion (constricts)
function of trochlear nerve?
eye movement (motor)
course of trochlear nerve?
leaves CNS at back of the midbrain
travel towards the orbit in the lateral wall of cavernous sinus
leaves cranium through superior orbital fissure
passes through SOF into the orbit and supplies superior oblique
function of abducent nerve?
eye movement (motor)
course of abducent nerve?
leaves CNS at pontomedullary junction
travels towards the orbit within the cavernous sinus
leaves cranium via SOF
passes through SOF into orbit and supplies lateral rectus
describe the H test?
tests nerves of eye movement
- down and in = SO
- up and in - IO
function of vestibulocochlear nerve?
hearing and balance (special sensory)
course of vestibulocochlear?
axons from cochlear and vestibular apparatus enter cranium via internal acoustic meatus into the posterior cranial fossa
axons travel posteromedially from the internal acoustic meatus to the pontomedullary junction
connect with CNS at pontomedullary junction
how is vestibulocochlear nerve tested?
rinne and weber test
function of spinal accessory nerve?
motor to sternocleidomastoid and trapezius
course of spinal accessory nerve?
leaves CNS at cervical spinal cord
ascends through foramen magnum then travels towards jugular foramen in posterior cranial fossa
then leaves cranium via jugular foramen in posterior cranial fossa
axons then go to supply SCM on deep surface then continue across posterior triangle to supply trapezius and SCM
how can spinal accessory be tested?
shrug shoulders - trapezius
flex neck and turn to opposite side - SCM
also check for wasting etc
function of hypoglossal nerve?
motor (muscles of tongue)
course of hypoglossal nerve?
leaves CNS via many rootlets between the pyramids and olives of the medulla
passes anteriorly to hypoglossal canal
leaves cranium via hypoglossal canal in posterior cranial fossa
then descends lateral to the carotid sheath
at the level of the hyoid, it turns anteriorly towards lateral aspect of the tongue
supplies most muscles of the tongue apart from palatoglossus (vagus)
how is hypoglossal nerve tested?
ask patient to stick tongue straight out
- if both CN XIIs are working it will go straight
- if there is unilateral CN XII pathology then tongue will point to affected side
divisions of trigeminal nerve?
ophthalmic = sensory maxillary = sensory mandibular = sensory and motor
course of trigeminal nerve?
leaves CNS at pons (between midbrain and medulla)
travels inferior to the edge of the tentorium cerebelli between posterior and middle cranial fossae
V1 leaves cranium via superior orbital fissure
V2 leaves via formane rotundum
V3 leaves via foramen ovale
sensory axons from all 3 divisions course from superficial and deep structures of the face posteriorly towards their respective cranial foramen
motor axons from V3 course from foramen ovale towards the skeletal muscle they supply
what does V1 supply?
upper eyelid cornea (corneal reflex) conjunctiva skin over roof/bridge/tip of nose bones and soft tissue of orbit upper anterior nasal cavity paranasal sinuses anterior and posterior cranial fossae
what does V2 supply?
skin over lower eyelid skin over maxilla skin over ala of nose skin/mucosa of upper limb lower posterior nasal cavity maxilla and maxillary sinus floor os nasal cavity/palate maxillary teeth and associated soft tissue
what does V3 supply sensation to?
skin over mandible and TMJ middle cranial fossa mandible anterior 2/3 tongue (sensation) floor of mouth buccal mucosa mandibular teeth
function of tensor veli palatine?
tenses palate
opens eustachian tube?
motor function of V3?
3 pairs of jaw closing muscles - masseter - temporalis - medial pterygoid 1 pair of jaw closing muscles - lateral pterygoid tensor veli palatine tensor tympani
trigeminal sensory testing?
close eyes and gently brush skin in each dermatome
trigeminal motor testing?
palpate strength of contraction of the masseter and temporalis by asking patient to clench teeth
ask patient to open jaw against resistance
function of facial nerve?
special sensory (teste)
motor
parasympathetic
course of facial nerve?
leaves CNS at anterolateral pontomedullary junction
travels directly into internal acoustic meatus in the posterior cranial fossa
leaves cranium via stylomastoid foramen in temporal bone
most somatic motor axons pass into parotid gland, then into 6 branches that supply muscles of facial expression
(fibres of chorda tympani enter cranial fossa via internal acoustic meatus in temporal bone)
course/function of chorda tympani?
posterior wall of tympanic cavity, past incus and malleus and tensor tympani then out of tympanic cavity
carries special sensory of taste back to brain
carries parasympathetic fibres form brainstem to glands
site of lesion on facial nerve?
symptoms can determine whether the lesion is before or after the chroda tympani branches off the facial nerve
how is the facial nerve tested?
raise eyebrows (frontalis)
close eyes tightly (orbicularis oculi)
smile (elevators of lips)
puff out cheeks and hold air (orbicularis oris)
functions of glossopharyngeal nerve?
special sensory (taste) sensory motor visceral afferent parasympathetic
course of glossopharyngeal?
leaves CNS from lateral superior medulla
travels towards jugular foramen in posterior cranial fossa
leaves cranium via jugular foramen
descends to pharynx and larynx
- stylopharyngeus, parotid, pharyngeal mucosa, carotid body/sinus, posterior 1/3 tongue
general sensory function of glossopharyngeal?
posterior 1/3 tongue mucosa of pharynx palatine tonsils eustachian tube middle ear cavity
special sensory function of glossopharyngeal?
vallate papillae (with taste buds)
visceral afferent function of glossopharyngeal?
visceral afferents to carotid sinus baroreceptors and carotid body chemoreceptors
somatic motor function of glossopharyngeal?
stylopharyngeus
parasympathetic function of glossopharyngeal nerve?
parotid gland
clinical relevance of glossopharyngeal?
can be used in carotic massage
massage increases pressure sending signal via glossopharyngeal causing vagus to calm down heart
involved in gag reflex
associated with referred pain between ear and throat
modalities of vagus?
sensory
motor
visceral afferent
parasympathetic
course of vagus?
leaves CNS via lateral medulla (inferior to CN IX)
travels towards jugular foramen in posterior cranial fossa
leaves cranium via jugular foramen
axons supply lots of structures between palate and midgut
vagus nerve in the neck?
runs within carotid sheath posterior to and between the common carotid artery and internal jugular vein
runs inferiorly into the thorax then gives off recurrent laryngeal nerve to turn back superiorly to supply muscles of larynx
- left curves under aortic arch
- right curves under right subclavian artery
vagus nerve in chest?
right
- on lateral aspect of trachea
left
- on lateral aspect of aortic arch
both pass posterior to long root and onto oesophagus
both pass through diaphragm with oesophagus
vagus nerve in abdomen?
passes onto surface of stomach branches to - spleen - pancreas - celiac and superior mesenteric ganglia - kidneys - midgut - parasympathetic axons to splenic flexures of colon
how is vagus nerve tested?
say "ahh" (muscles of palate) - uvula will point towards normal side in unilateral pathology swallow water (pharyngeal muscles) - splutter = abnormal swallow listen to speech (laryngeal muscles)
