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Flashcards in Head and Neck, Session 4 Deck (114):

What is the first cranial nerve, and what does it supply?

olfactory nerve: contains only special sensation fibres and is distributed to uppermost part of nasal cavity, and is concerned with smell


why might a loss of smell be associated with a fracture of the ethmoid bone?

the olfactory nerve concerned with smell reaches the nose via the cribiform plate of the ethmoid bone.
Fractures of ethmoid involving dura mater may be assoc. with CSF leakage from nose


general sensory fibres of facial nerve supply what?

part of external acoustic meatus and auricle


how is innervation provided to the carotid sinus and carotid body?

via the the sinus nerve branch of the glossopharyngeal nerve


general sensory distribution of glossopharyngeal nerve?

pharynx, oropharyngeal isthmus, dorsum of palate, auditory tube + assoc structures, mastoid antrum, mastoid cells


which nerves are sensory to the external acoustic meatus and auricle?

facial and vagus nerves
vagus- back of auricle


which palate muscle is not supplied by the vagus nerve?

tensor veli palatine


which cranial nerve has both a cranial and spinal part?

accessory nerve (XI)
cranial root accessory to vagus


fibres from which roots are contained by the spinal root of the accessory nerve?



motor supply of hypoglossal nerve?

all muscles of tongue, except palatoglossus


other name given to infrahyoid muscles?

strap muscles of neck


what is formed by some cervical nerves frrom C1, C2 and C3 being looped onto the hypoglossal nerve?

ansa cervicalis
these fibres are distributed to strap muscles of neck


where do the cervical sympathetic trunks lie?

pass vertically up to base of skull, lying on prevertebral fascia and muscles, and lying deep to carotid sheath


where do the postganglionic fibres from the superior cervical ganglion pass?

with the external and internal carotid artery and its branches, to the pharyngeal plexus, to the upper 4 cervical nerves and in a cardiac branch to the cardiac plexus


with which artery do the post-ganglionic fibres of the middle cervical ganglion pass?

inferior thyroid


where do the post-ganglionic fibres of the middle cervical ganglion run to?

the 5th and 6th cervical nerves and in a cardiac branch to the cardiac plexus


how is the stellate ganglion formed?

combination of inferior cervical ganglion and 1st thoracic ganglion


with which artery do post ganglionic fibres from inferior cervical ganglion pass?

vertebral artery


what are the 4 pairs of parasympathetic ganglia in the head?

ciliary- oculomotor nerve
pterygopalatine- facial nerve
submandibular- facial nerve
otic- glossopharyngeal nerve


where is the ciliary ganglion?

lies in orbital cavity, lateral to optic nerve
PNS fibres pass to ciliary muscles and sphincter papillae


where is the pterygopalatine ganglion?

lies in pterygopalatine fossa
connected to maxillary nerve by small branches


receptive field territory of olfactory nerve?

nasal cavity, L and R supplied by separate L and R nerves


how does olfactory nerve form olfactory bulb?

nerve process leaves nasal cavity to ascend intra-cranially via foramina of cribiform plate of ethmoid, where they form olfactory bulb in the anterior cranial fossa


how may fracture of cribiform plate be experienced by a patient if olfactory nerve involvement?

anosmia, CSF rhinorrhea- drainage of CSF into the nose


when may sense of smell be tempoararily lost?

e.g. allergic rhinitis- inflammation of nasal mucous membrane


why is loss of smell associated with ageing?

progressive reduction of olfactory receptor neurones in olfactory epithelium


why is each nostril tested separately for sense of smell with specific odours e.g. coffee, vanilla

as anosmia tends to be unilateral- and person may not be aware of this until clinical testing


when might CSF rhinorrhea occur?

cranial base fracture, with dura mater involvement, or fractures of cribiform plate


how might olfactory nerve/bulb be compressed causing anosmia?

tumor/abscess in frontal lobe of brain, or tumor of meninges (meningioma) in A cranial fossa


what may accompany lesions in temporal lobe of the cerebral hemisphere?

olfactory hallucinations- sensation of smell without sensory source


why may smelling salts be used to re-boot the brain after loss of consciousness?

stimulate the olfactory nerve whose sensations are conveyed to the cerebral cortex directly without going through the thalamus- derivative of diencephalon


describe the course of optic nerve fibres?

arise from ganglion cells in retina. nerve fibres exit orbit via optic canals to enter middle cranial fossa where optic chiasm formed where fibres from medial half of each retina cross in chiasm and join uncrossed fibres from lateral half of retina to form optic tract


what must be tested to examine visual system?

visual acuity
colour vision
visual fields
pupillary reflexes


why are optic nerves susceptible to multiple sclerosis which does not normally affect other nerves of parasympathetic nervous sytem?

optic nerves are actually CNS tracts so myelin sheath surrounding fibres from point at which they penetrate the sclera is formed by oligodendrocytes rather than schwann cells


what is optic neuritis?

lesions of optic nerve that cause diminution of visual acuity, with or without changes in peripheral fields of vision


how might loss of pupillary constriction result?

direct trauma to orbit or eyeball, fracture involving optic canal


how can visual field defects be produced?

pressure on optic pathway, laceration or intra-cerebral clot in temporal, parietal or occipital lobes of brain
tumours of hypothalamus can disturb vision, as well as aneurysms of internal carotid artery near the hypothalamus


muscles innervated by oculomotor nerve?

all extraoccular muscles except lateral rectus and superior oblique
levator palpebrae superioris muscle of upper eyelid
autonomic- PNS: through ciliary ganglion to smooth muscle of sphincter pupillae, causing constriction of pupil and ciliary muscle, producing accomodation- allows lens to become more rounded for near vision


first sign of oculomotor nerve compression and why?

ipsilateral slowness of pupillary response to light as autonomic fibres of nerve superficial, so affected 1st, and cause pupil to dilate progressively on injured side


result of oculomotor nerve lesion?

ipsilateral oculomotor nerve palsy- eye is down and out- involvement of extraocular muscles with unopposed actions of superior oblique and lateral rectus


what may cause a lesion of CNIII?

aneurysms of posterior cerebral or superior cerebellar, fracture involving cavernous sinus, cavernous sinus thrombosis, pressure from herniating uncus on nerve- uncus is part of olfactory area of brain

(as nerve lies in lateral wall of cavernous sinus)


abnomal findings if CNIII lesion?

dilated pupil, ptosis- due to non-functioning levator palpebrae superioris, eye turns down and out, pupillary reflex on side of lesion will be lost


how can levator palpebrae superioris be tested?

patient asked to look upward to see if elevation of eyelid accompanies this effort


pupillary reflex is consensual, what does this mean?

shining a light in 1 pupil into only 1 eye cause both pupils to constrict


paralysis of which muscle causes absent accomodation reflex?

ciliary muscles- ANS innervation from CNIII


contrast presentation of CNIII palsy with Horner's syndrome?

ptosis complete in CNIII palsy, but only patial in Horner's where problem with SNS


result of PNS innervation loss of CNIII?

pupil fixed and dilated due to denervation of constrictor pupillae


muscle supplied by trochlear nerve?

superior oblique


what is diplopia?

double vision


when does diplopia present in trochlear nerve dmaage?

when patient goes down stairs


what can patient with trochlear nerve damage be asked to do to elicit damage?

asked to look downwards when eye adducted (medial)


when might CNIV be damaged?

fracture of orbit, or stretching of nerve during its course around the brainstem


muscle supplied by abducent nerve?

lateral rectus muscle


abnormal finding when abducent nerve lesion?

eye fails to move laterally, would be adducted on resting gaze, double vision (diplopia) on lateral gaze


how may abducent nerve be damaged?

fractures involving cavernous sinus or orbit


muscles supplied by mandibular division of trigeminal nerve?

medial and lateral pterygoids
tensor tympanis
tensor veli palatini
anterior belly of digastric


sensory territories of opthalmic division of trigeminal nerve?

upper eyelid
dorsum of nose
eye sensations- conjunctiva and cornea


what is the corneal reflex?

blinking in response to cornea being touched


which muscle contracts to cause a blink reflex?

orbicularis oculi


sensory territories of maxillary division of trigeminal nerve?

skin of lower eyelid
skin of cheek
skin of upper lip
mucosa of nasal cavity
mucosa lining paranasal sinuses
mucosa lining palate
roots of upper teeth


how is boundary of maxillary and mandibular division on CNV marked exteriorly?

by angle of mouth


sensory territories of mandibular division of CNV?

skin of temples, skin of cheeks, skin of chin, mucosa of inner cheek, anter 2/3 of tongue- lingual nerve- general sensation, roots of lower teeth


what does each muscle of mastication do to the jaw?

temporalis- closes
masseter- closes
medial pterygoids- opens
lateral pterygoids- closes
A belly of digastric- opens


how does mandible move if CNV lesion?

deviates to side of lesion when mouth is opened


where might maxillary division of CNV be damaged?

in roof of maxillary sinus


which CN may be damaged to cause loss of sneezing reflex?

maxillary division supplies mucosa of nasal cavity


why does diplopia occur when looking dward in a CNIV lesion?

superior oblique muscle normally assists inferior rectus in depressing pupil and is only muscle to do so when pupil adducted


why is forehead wrinkling not visibly impaired in central lesion of CN VII?

innervated bilaterally (frontalis muscle)


what does damage to motor division of facial nerve cause?

loss of facial expression
loss of sphincter function
loss of naso-labial fold


via which nerve is taste in anterior 2/3 of tongue supplied?

chorda tympani- part of facial nerve


glands and mucous membranes supplied by ANS division of facial nerve?


nasopharynx, paranasal sinuses- secretory function, hard palate, soft palate


general sensation of facial nerve?

concha of auricle and behind the ear


how can facial nerve be tested?

raise eyebrows
wrinkle forehead, close eyes tightly
broad smile
puffing out of cheeks- buccinator and orbicularis oris


what would be abnormal findings from fracture of temporal bone damaging facial nerve?

facial muscle parlaysis, eye remains open, angle of mouth droops, forehead doesn't wrinkle, dry cornea, loss of taste on A 2/3 of tongue


effect on patient of intracranial haematoma affecting facial nerve?

forehead wrinkles as bilateral innervation of frontalis, otherwise paralysis of contralateral facial muscles


result of damage to facial nerve in parotid region?

facial muscle paralysis, eyes open, angle of mouth droops, forehead does not wrinkle


what nucleus provides the origin of the pre-ganglionic neurones for the parasympathetic outflow of CNIII?

Edinger-Westphal nucleus


what nucleus provides the origin of the pre-ganglionic neurones for the parasympathetic outflow of CNVII?

Superior salivatory nucleus


what nucleus provides the origin of the pre-ganglionic neurones for the parasympathetic outflow of CNIX?

Inferior salivatory nucleus


what nucleus provides the origin of the pre-ganglionic neurones for the parasympathetic outflow of CNX?

Dorsal vagal motor nucleus


which cranial nerves have sensory and motor function?

trigeminal, facial ,glossopharyngeal, vagus


where does the oculomotor nerve lie?

in lateral wall of cavernous sinus


what is the relationship of the oculomotor nerve to postganglionic sympathetic fibres?

nerve allows fibres from superior cervical ganglion via the plexus on the opthalmic artery to latch on to superior branch of nerve at level of ciliary ganglion to innervate smooth muscle component of levator palpebrae superioris


via which nerve do pre-ganglionic PNS fibres of facial nerve enter pterygopalatine ganglion?

greater petrosal nerve


what do post-ganglionic neurones of facial nerve from pterygopalatine ganglion supply parasympathetic innervation to?

lacrimal gland, glands of nose, palate and nasopharynx


via which nerve do PNS fibres of facial nerve reach submandibular ganglion?

chorda tympani branch


triad of symptoms in horner's syndrome?

partial ptosis
hemifacial anhidrosis


describe the anatomical association of the trigeminal nerve with organisation of ANS outflow

ciliary ganglion- related to opthalmic division
pterygopalatine- related to maxillary division
submandibular- related to maxillary division
otic- related to mandibular division


presentation of patient with facial nerve damage within post wall of tympanic cavity?

chorda tympani branch, so loss of taste to A 2/3 of tongue and on salivation and lacrimation


how can CN VIII be tested?

by whispering numbers to each ear with other ear closed


how can sensori-neural and conductiove hearing losses be differentiated between?

using rinne's test and weber's test- tuningg fork tests


why would ear with conductive hearing loss be ear which sound is heard loudest in weber's test?

external noise overpowers unaffected ear if conductive hearing loss in affected ear


what does damage to vestibular nerve cause?

loss of balance
nystagmus- uncontrolled movement of eyes, usually from side to side
impairment of caloric response: normal response=COWS: Cold Opposite, Warm Same.
Cold water = FAST phase of nystagmus to the side Opposite from the cold water filled ear
Warm water = FAST phase of nystagmus to the Same side as the warm water filled ear


what would happen if tumour of CNVIII (acoustic neuroma)- benign neoplasm of schwann cells?

progressive unilateral hearing loss, tinnitus


general sensory innervation provided by CNIX?

pharynx, middle ear cavity, tonsillar sinus, pharyngotympanic tube


test for CNIX function?

gag reflex (pharyngeal relex)- reflex pharyngeal constriction when back wall of oropharynx touched by non-food substances
sensory limb of reflex, motor= vagus


what would happen if lesion of CNIX in brainstem of due to laceration of neck?

loss of taste on post 1/3 of tongue, loss of sensation on affected side of soft palate


effects of tumours in region of jugular foramen?

multiple cranial nerve palsies= jugular foramen syndrome, as CNs IX, X and XI pass through foramen


motor innervation of CNX?

intrinsic muscles of larynx and pharynx
muscles of palate
smooth muscle- bronchi, DT
secretomotor- thoracic and abdom viscera


sensory innervation of CNX?

external ear, auditory canal and eardrum
pharynx and larynx
visceral sensation- thorax and abdomen


symptoms if damage to R recurrent laryngeal nerve only?

VC slight adducted on that side, causing hoarse voice, weak cough and risk fluid aspiration, dysphonia


injury to pharyngeal branches of vagus causes..?



what happens if injury of superior laryngeal nerve?

anesthesia of superior part of larynx and paralysis of cricothyroid muscle
voice weak and tires easily


what happens if paralysis of both recurrent laryngeal nerves?

aphonia (voice loss) and inspiratory stridor- harsh, high pitched respiratory sound


L recurrent laryngeal nerve lower than R, with longer course, why is this a problem?

more susceptible to damage, may be affected in bronchial or oesophageal carcinoma, or enlarged mediastinal LNs, of if aortic arch aneurysm


what nerve might a thyroidectomy damage?

vagus- superior laryngeal branch, external branch lies close to superior thyroid artery- branch of external carotid


why might mitral stenosis present with hoarse voice?

left atrial enlargement, pushes up the left pulmonary artery, compressing the L recurrent laryngeal nerve against aortic arch


how does spinal division of CNXI join cranial division?

originates in SC and ascends intra-cranially via foramen magnum
combined nerve then exits brain via jugular foramen


how is CNXI tested for?

inspect for wasting of SCM and/or trapezius
test for wkness of SCM- ask patient to rotate head against resistance
wkness of trapezius- shrug shoulders against resistance


when might CNXI be susceptible to damage?

in LN biopsy, cannulation of IJV, and carotid end arterectomy as nearly SC passage through posterior cervical region


what would happen if laceration of neck damaged CN XI?

paralysis of SCM and S fibres of trapezius, so shoulder drooping


when might CN XII be damaged?

neck laceration, basal skull fractures


result of CN XII damage?

protruded tongue deviates towards affected side, moderate disturbance of articulation


how to check for CN XII damage?

inspect for tongue wasting and fasciculations of protrusion, and ask them to move tongue from side to side