Head and Neck review Flashcards
What is a fontanelle?
a large membranous, unossified gap that exists in the neonate and the newborn between the bones of the skull.
Anterior= where coronal and sagittal sutures will meet
Posterior= where sagittal and lambdoid sutures will meet
function of fontanelles?
allow movement of skull bone during birthing process so head can deform as it passes out through the birth canal, so moulding occurs
allow for post-natal growth
how is neonatal skull different from adult?
sutures between adjacent cranial bones open in newborn, closed in adult
2 frontal bones normally fuse, but occasionally persist in the adult (metopic suture)
Bony proportions different – facial skeleton small at birth
Alveolar processes and paranasal sinuses rudimentary at birth
When does the anterior fontanelle and posterior fontanelle close?
anterior- within 2 yrs
posterior- within 6-9mnths
Problem of small foetal mastoid process during childbirth?
forceps may damage facial nerve as will be relatively superficial so close to surface as it emerges from the stylomastoid foramina
what is the antrum in the facial skeleton?
maxillary sinus in body of maxilla
3 major divisions of trigeminal nerve before leaving middle cranial fossa?
opthalmic
maxillary
mandibular
where does the mandibular nerve exit the skull?
foramen ovale
why might a fracture of the mandible cause numbness of the lower lip?
damage to the inferior alveolar nerve, a branch of the mandibular nerve which is a branch of the trigeminal nerve, which hence causes a loss of function of the mental nerve which branches from the inferior alveolar nerve, passes through the mental formaina in the body of the mandible and innervates the oral mucosa of the inferior lip
What is the ligamentum nuchae?
It is a thickened fibroelastic tissue that attaches to the external occipital protuberance and the posterior border of the foramen magnum to the spinous processes of the cervical vertebrae.
What does the ligamentum nuchae help to do?
maintain normal curvature of cervical spine
why are cervical vertebrae prone to dislocation in whiplash injuries?
almost horizontal alignment of the articular facets between adjoining vertebrae.
problem of a posterior prolapse of IV disc between C2 and C3?
The prolapse may cause pressure on the spinal cord above the phrenic nerve outflow of C3, C4 and C5. If this happens suddenly, respiration will cease as phrenic nerve innervates the diaphragm which is necessary for inspiration (respons. for 70% of chest expansion in quiet respiration)
where does the middle meningeal artery enter the cranial cavity?
through foramen spinosum, and then lies just behind pterion
type of cranial fracture causing an epidural haematoma?
depressed fracture
what might a depressed fontanelle mean?
dehydration
what might a bulging fontanelle indicate?
increased intra-cranial pressure
where is the stylomastoid foramen located?
on lower surface of temporal bone, between the styloid and mastoid processes
how are the head and face positioned in congenital torticollis?
head tilts toward, and face turns away from, the affected side
how does the articular capsule of TMJ fit the mandibular fossa and articular tubercle?
upper surface of disc is concavo-convex (A-P)
why is an infection deep in the pterygoid region of danger to the eye?
pterygoid venous plexus located in the infratemporal fossa is connected with both the opthalmic and anterior facial veins, it drains into the cavernous sinus- receives blood from s and i opthalmic veins, so infection may cause a cavernous sinus thrombosis which can cause paralysis of extraocular muscles, or pus from infection may cause direct increased opthalmic venous pressure
what is the parotid duct and how can it be palapated?
route that saliva takes from parotid gland, into the mouth
when jaw clenched tight, it can be felt lying on the contracted masseter muscle
when does the parotid duct enter the mouth?
on piercing the buccinator muscle (CN XII), it opens into the mouth opposite the second upper molar tooth
function of occipitofrontalis
occipital belly: scalp retraction, increasing effectiveness of frontal belly, innervated by post auricular branch
frontal: protracts scalp, elevates eyebrows and wrinkles skin of forehead
function of orbicularis oculi
closes eyelids, palpebral part gently and orbital part tightly- winking
function of orbicularis oris
tonus closes oral fissure, phasic contraction compresses and protrudes lips (kissing) or resists distension (when blowing)
function of buccinator
presses cheek against molar teeth, works with tongue to keep food between occlusal surfaces and out of oral vestibule, resists distension (when blowing)
function of platysma
depresses mandible (against resistance), tenses skin of inferior neck and face- conveys stress and tension
causes of facial nerve palsy?
facial nerve palsy of newborn parotidectomy tumours or aneurysms inflammation near stylomastoid foramen e.g. due to viral infection fracture of temporal bone
difference between facial nerve palsy and bell’s palsy?
bell’s: unknown cause, tend to recover
facial: known cause, no recovery
how is facial nerve palsy differentiated from a stroke?*
forehead wrinkling spared in a stroke, but not in facial nerve palsy as bilateral innervation of facial nerve
what is a periorbital ecchymosis?
purplish/reddish discolouration of skin around orbit due to blood in SC tissue and skin that has been extravasated, can spread from scalp into eyes
where is the cavernous sinus located?
on the upper surface of the sphenoid bone
how do cavernous sinuses on each side communicate?
by intercavernous sinus
what does the cavernous sinus drain into?
the basilar and pterygoid venous plexuses via emissary veins
what is the pterygoid venous plexus?
situated between temporalis and lateral pterygoid muscles
receives venous drainage from venae comitantes of maxillary artery
anastomoses with facial vein via deep facial vein, cavernous sinus, and is drained by the maxillary vein
what branches does the facial nerve give rise to in the facial canal?
chorda tympani
greater petrosal nerve
nerve to stapedius
how is cauliflower ear produced?
trauma to external ear may cause a haematoma to form between the perichondrium and cartilage. Blood from perichondrium may then be unable to supply cartilage, so necrosis occurs as cartilage avascular, and subsequent fibrosis and deformity results.
why might a child with recurrent middle ear infections benefit from adenoidectomy?
adenoids probable blocking Eustachian tube, compromising equlibration of air pressures, causing -ve pressure in tympanic cavity with resultant air absorption and a concentrated mucus secretion predisposing to infection, and mucus secretion can be drained into nasopharynx if eustachian tube blockage removed
what causes shape of face to change when permanent teeth eruption and subsequent puberty?
growth of PN sinuses
why might otalgia be result of referred pain?
innervation of inner part of tympanic membrane in middle ear is via glossopharyngeal nerve, which also innervates the oropharynx, so something like tonsillitis of pharyngitis may present as otalgia
difference in presentation between an upper and a lower motor nerve palsy of the facial nerve?*
upper= forehead sparing, so can still wrinkle skin of forehead on affected side lower= no forehead sparing as lesion after bilateral innervation, so no innervation to occipitofrontalis
innervation of parotid gland?
glossopharyngeal nerve- synapses in otic ganglion
nerve which branches in parotid gland to give 5 terminal extracranial branches, and names of these branches?
facial nerve temporal zygomatic buccal marginal mandibular cervical
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how would a patient with left hypoglossal nerve palsy present?
when asked to protrude tongue, it would deviate towards the left side
tongue would also show furrows on left side (grooves)
tongue would atrophy on L side in long term
which branch of the superior laryngeal nerve supplies the cricothyroid muscle?
external laryngeal nerve
function of cricothyroid?
It tenses vocal cords, increasing pitch. It also controls expiration of air in phonation.
what might happen if paralysis of cricothyroid?
difficult maintaining patent airways in breathing and swallowing as muscle
with which nerve do the glossopharyngeal post-ganglionic PNS fibres reach the parotid gland?
auriculotemporal from mandibular division of trigeminal
why might horner’s syndrome be associated with an arterial problem?
sympathetic nerve fibres hitch hike onto arteries of head and neck to supply their target structures:
from S cervical ganglion via ICA and ECA
from middle via I.thyroid
from inferior via vertebral
innervation loss to dilator pupillae and superior tarsal- ptosis and miosis of horners, and vasomotor function loss causes anhydrosis
how is the hyoid helped to be suspended by the pre-tracheal layer of deep cervical fascia?
fascia thickens superiorly to hyoid, forming a trochlea through which intermediate tendon of digastric passes (suprahyoid muscle)
where is the parapharyngeal space?
lateral to pharynx, close to carotid sheath structures, up to level of mediastinum. Tonsillitis may cause quinsy- peritonsillar abscess, or can enter space and spread into chest. May be drooling, won’t want to open mouth.
muscle comprising epicranial group of facial muscles?
occipitofrontalis
orbital group of facial muscles?
orbicularis oculi
corrugator supercilii- eyebrows drawn inferiorly and medially as concerned or worried
function of procerus and transverse part of nasalis?
Wrinkling skin over dorsum of nose-shows
Disdain or dislike
Flares nostril
dilators of mouth?
risorius, levator labii superioris, depressor labii inferioris
consequence of non-functioning orbicularis oris?
can’t close mouth, so uncontrollable drooling
smiling muscles?
levator anguli oris
zygomaticus major
saddness muscles?
depressor anguli oris
zygomaticus minor
undifferentiated tissues of what origin forms fascia?
mesenchyme
why is it useful to view neck as territories of triangles?
describe lumps in neck, provide clues as to where they have arisen from, as organised layout of neck anatomical structures
define muscular torticollis
dominant contraction of 1 SCM
how can a subdural haematoma be aspirated from a small baby?
use anterior fontanelle- larger, closes later
sensory innervation of neck?
cutaneous branches of cervical nerves from cervical plexus, extend upwards onto face- parotid region, area overlying angle of mandible
what is the neurocranium?
bony case of brain and cranial meninges, comprises calvaria and cranial base
what is the viscerocranium?
facial skeleton
b.supply to viscercranium?
ECA
blood supply to neurocranium?
ICA?
middle meningeal artery
if facial artery lacerated on 1 side of face, why is it necessary to compress both arteries to stop bleeding?
Because the artery has many anastomoses with other arteries of the face
major route of spread of infection from neck into thorax?
retropharyngeal space
contents of submandibular triangle of neck?
SM gland, LNs, hypoglossal and mylohyoid nerve, parts of facial artery and vein
contents of submental triangle of neck?
SM LNs, small veins which unite to form AJV
contents of carotid triangle?
Carotid sheath o Common carotid artery o Internal jugular vein o Vagus nerve o Deep Cervical Lymph Nodes Thyroid gland Larynx Pharynx External carotid artery and some of its branches Hypoglossal and Spinal accessory nerves Branches of cervical plexus
contents of muscular triangle of neck?
sternohyoid and sternothyroid infrahyoid muscles
thyroid and PT glands
what anstomosis supplies blood to brain and what is it formed by?
circle of Willis
R and L vertebral arteries from subclavian arteries, and ICA
which is the strongest cervical vertebra and why?
C2
as C1 carrying the skull rotates on it
infrahyoid muscle function?
depression hyoid and larynx in swallowing and speaking
work with suprahyoid to steady hyoid and so provide a firm base for tongue
4 infrahyoid muscles?
omohyoid
sternothyroid
thyrohyoid
sternohyoid
4 suprahyoid muscles?
digastric
mylohyoid
stylohyoid
geniohyoid
contents of large occipital triangle of posterior triangle?
accessory nerve, BP trunks, part of EJV, post branches of cervical plexus, cervical LNs, cervicodorsal trunk
contents of omoclavicular triangle of post triangle?
3rd part of SC artery, part of SC vein, suprascapular artery, supraclavicular LNs
borders of carotid triangle?
superiorly: P belly of digastric
medially: S belly of omohyoid
laterally: A border of SCM
overall function of hyoid muscles?
steady/move hyoid and larynx
scalp blood supply?
ECA: p auricular, occipital, superficial temporal
ICA: opthalmic- supra-orbital and supratrochlear
why would loss of scalp b supply not damage skull?
skull supplied by middle meningeal artery
why would involvement of epicranial aponeurosis in scalp laceration cause more profuse bleeding?
2 bellies of occipitofrontalis pull on aponeurosis in opp. directions to produce deeper cut
why might a parathyroid adenoma occur in the chest?
parathyroid tissue can be moved down with the thymus gland as the 3rd pharyngeal pouch gives rise to the PT glands and the thymus
why does the TMJ rarely dislocate posteriorly?
strengthened poster. by postglenoid tubercle poster. and intrinsic lateral ligament= extracapsular ligament
sphenomandibular ligament funtion? (from spine of sphenoid bone to mandible)
prevent inferior dislocation of TMJ
nerves that may be damaged in TMJ dislocation?
facial nerve
auriculotemporal nerve- from mand division of trigeminal, and carries post-gangl fibres of glossopharyngeal nerve to parotid gland from otic ganglion
