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?
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?
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?
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?
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?
what is diplopia?
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 veli palatini
anterior belly of digastric
sensory territories of opthalmic division of trigeminal nerve?
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?
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?
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?
wrinkle forehead, close eyes tightly
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?
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?
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