Flashcards in Head and Neck, Session 1 Deck (89):
What is a suture?
type of fibrous joint in terms of its structure, and synarthrosis in terms of function
virtually no movement
attaches bones of skull together, apart from mandible which forms the lower jaw
why is the mandible moveable?
articulates with the cranial base at the temporomandibular joint
How may cervical pain be caused?
displacement/protrusion of inter-vertebral discs
what do the buccinators do?
these are the muscles of the cheek, keep cheek taut and aid in chewing
nerve supply to muscles of mastication?
mandibular division of trigeminal nerve (branch of 5th cranial nerve)
what does the facial nerve (7th cranial) supply?
derivatives of 2nd pharyngeal arch:
muscles of facial expression
muscles of ear e.g. stapedius
P belly of digastric
where does the facial nerve divide into extracranial branches?
what is the facial artery a branch of?
the external carotid
which artery provides main arterial supply to face?
what does the external carotid artery terminate as?
the superficial temporal and maxillary arteries
drainage of blood from face?
facial vein into internal jugular vein=MAIN
superficial temporal vein, maxillary and others form external jugular vein
both internal and external jugular drain into subclavian
*L subclavian vein receives drainage from thoracic duct in superior mediastinum
what is bell's palsy?
paralysis of facial muscles due to dysfunction of facial nerve- can be compressed in the intracranial facial canal by inflammation near its exit from cranium at stylomastoid foramen as oedema
why might surgery on parotid gland cause facial paralysis?
may damage facial nerve innervating muscles of facial expression as nerve and its branches pass through gland
what is enclosed by the investing layer of deep cervical fascia which surrounds entire neck, deep to skin?
sternocleidomastoid, trapezius, parotid and submandibular salivary glands
what is the 2nd layer of deep cervical fascia?
this forms a muscular layer enclosing infrahyoid muscles (strap)- thyrohyoid, sternothyroid, sternohyoid, omohyoid , and visceral enclosing thyroid gland, trachea and oesophagus
laterally blends with carotid sheath
what do the carotid sheaths enclose?
common carotid artery
internal jugular vein
deep cervical LNs
what is the innermost layer of deep cervical fascia?
forms a sheath for VC and assoc muscles
extends from base of cranium of 3rd T vertebra, and extends laterally as axillary sheath
where might an infection occur that can spread into thoracic cavity anterior to pericardium?
between investing layer of deep cervical fascia and visceral layer of the pretracheal layer of deep cervical fascia
symptoms of patient with a retropharyngeal abscess?
what is the retropharyngeal space?
potential space between prevertebral layer of fascia and fascia surrounding pharynx superficially (buccopharyngeal fascia)
what is the pterion?
the junction where the frontal, parietal, sphenoid and temporal bones are in close proximity
clinical relevance of pterion?
fractures of skull in this region very serious
bone part. thin and lateral fracture may lacerate middle meningeal artery (anterior divison of)- from the maxillary from ECA, casing an epidural arterial haematoma between skull and periosteal layer of dura mater, haematoma exerts pressure on underlying cerebral cortex
what is a countercoup fracture?
fracture occurs on opp side of cranium rather than at site of impact
how may an infection of the scalp cause osteomyelitis- an infection of bone?
infection can spread to skull bones via emissary veins which connect superficial veins of scalp with diploic veins of skull bones and with intracranial venous sinuses
which bone forms the upper jaw?
maxillae, fixed to cranial base
how is the odontoid (dens) process of C2 held in place?
transverse ligament of atlas
how can bleeding from common carotid arteries be controlled?
by compression against anterior tubercles of C6, found at ending of transverse processes (carotid tubercles)
what is a simple skull fracture?
break in bone without damage to skin
what is a linear skull fracture?
thin line, without splintering, depression or distortion of bone
what is a depressed skull fracture?
bone pushed towards brain
what is a compound skull fracture?
break in or loss of skin, and splintering of bone accompanied by brain injury and bleeding
what is the calvaria?
vault of the skull formed by cranial bones, forms roof of cranial cavity, protecting superior aspect of brain.
comprises frontal bone anteriorly, paired parietal bone in middle and occipital bone post.
what sutures are visible internally in calvaria?
coronal suture: between frontal and parietal bones
sagittal: between paired parietal bones
lambdoid: between parietal and occipital bones
visible junctions of these sutures are the bregma- where coronal and sagittal meet, and lambda, where lambdoid and sagittal meet
which are the main bones contributing to the cranial base (floor of cranial cavity)?
sphenoid, temporal and occipital bones
at which joint do the muscles of mastication act?
main muscle groups in head?
muscles of facial expression
muscles of mastication
why can pulse of facial artery be palapated?
as passes around inferior border of mandible
what does the masseter muscle do?
elevates mandible, so closes mouth
what are the fascial spaces of the neck?
between fascial layers, provide conduit for spread of infection from neck to mediastinum
3 spaces: pretracheal
what are the boundaries of the anterior triangle?
anterior border of sternocleidomastoid posteriorly
inferior border of mandible superiorly
midline of neck anteriorly
boundaries of posterior triangle?
posterior border of sternocleidomastoid anteriorly
anterior border of trapezius posteriorly
middle 1/3 of clavicle basally
apically by occipital bone
why are movements of neck especially free?
IV discs thick relative to size of VB
articular surfaces of ZP joints relatively large, and joint planes almost horizontal
joint capsules of ZP joints loose
less surrounding soft tissue bulk in neck compared with trunk
which nerve provides sensory innervation to the face?
trigeminal nerve- opthalmic, maxillary and mandibular divisions
which nerve innervates the facial muscles?
what structures can be found passing through the posterior triangle?
external jugular vein
what is the mastoid process?
an inferior projection of temporal bone of skull, just posterior to ear
provides superior attachment site of sternocleidomastoid
where will infection spread if occurs between investing layer of deep cervical fascia and muscular part of pretracheal fascia enclosing infrahyoid muscles?
what if between investing and visceral part of pretracheal?
usually not beyond superior edge of manubrium
can spread into thoracic cavity anterior to pericardium
importance of retropharyngeal space?
major pathway for spread of infection from neck to thorax
proximal and distal attachments of trapezius muscle?
Proximal- medial 1/3 of superior nuchal line, external occipital protuberance, nuchal ligmanet, spinour processes of C7-T12 vertebrae
Distal- lateral 1/3 of clavicle, acromion and spine of scapula
descending part elevates, and ascending part depresses scapula, middle part retracts, D and A act to rotate GC superiorly
what is the only major opening of the box of the head?
why can bones of skull forming sutures interlock firmly?
serrated edges of bones, so are also less likely to be easily unlocked by force applied in 1 direction
type of bones forming skull?
function of middle layer of spongy bone- diploe, of the skull?
help reduce weight of cranium
bone marrow for haematopoiesis
name of suture joining bones of mandible?
2 separate bones of mandible?
L and R mandibles
main bones of cranial cap?
frontal, occipital, parietal, temporal
bone forming roof of orbit?
likely outcome of ethmoid fracture and why?
anosmia- ethmoid allows for passage of olfactory nerve (tract) fibres through cribiform plate
4 parts of occipital bone?
right and left condylar
why high probability of brain damage from trauma of normal birthing process if occurs prematurely?
cranial sutures are too wide open for pressures of birthing to result in interlocking of the cranial bones
type of CT forming superficial fascia?
type of CT forming deep fascia?
Dense irregular CT
only complete cartilage in larynx?*
branches of facial nerve when exits partoid gland?
muscles innervated by cranial nerve V?
medial and lateral pterygoid
A belly of digastric
tensor veli palatini
bones of skeleton of neck?
manubrium of sternum
why large vertebral foramina in comparison to VB in cervical region?
SC at its largest within this region as all the nerves which are going to pass d.wards e.g. to supply UL must pass through here
why small, saddle shaped VB in cervical region?
less support needed for body axis in comparison to lower vertebrae
characterisitcs of C3-C6 vertebrae?
small VB, longer from side to side than AP, superior surface concave, infer convex
large and triangular vertebral foramen
foramina transversaria for vertebral vessels in transverse processes
spinous processes short and bifid
superior facets of articular processes directed superoposteriorly, inferior directed inferoposteriorly
describe the bone of the cranium?
2 plates of compact bone- outer and inner, giving resilience due to compact packing
and 1 middle layer of spongy bone- lessens weight of cranium, and BM so site of haemopoiesis. middle layer= diploe
articulations of bones of cranial base*?
atlas, facial bones and mandible
why is the cranial base (part of calvaria) susceptible to fracture?
large number of foramina for passage of anatomical structures between extra and intra cranial compartments make floor of cranium weak, so base liable to fracture in high energy impacts to head
where is the stylomastoid foramina?
between styloid and mastoid processes of temporal bone
symptoms of skull fractures?
Bleeding from the wound, ear, nose or around eyes, bruising, draining of CSF from ears or nose, swelling, confusion, convulsions, difficulties with balance, drowsiness, headache, loss of consciousness, nausea, vomiting, visual disturbance, stuff neck and slurred speech.
what is a linear calvarial fracture (most frequent type of calvarial fracture)?
fracture at site of impact, but fracture lines radiate away from it in 2 or more directions
What is a Basal Skull Fracture?
Fracture of skull base, presents with Battle’s Sign- subcutaneous purpura - extravasated blood, of mastoid process of temporal bone
how may superciliary arches be damaged?
during boxing- sharp blow to them can lacerate skin and cause bleeding, as relatively sharp bony ridges. Bruising surrounding orbit cause tissue fluid and blood to accumulate in surrounding CT, which gravitates into superior eyelid and around eye- black eye
What is a malar flush?
redness of skin covering zygomatic prominence, assoc with rise in temp in fevers assoc with for example TB and SLE- butterfly rash
When do facial fractures commonly occur?
In Car accidents, fistfights and falls which commonly involve the nasal bones due to the prominence of the nose.
Maxillofacial fractures occur as a result of massive facial trauma. A hard blow to the lower jaw often results in a fracture of the neck of the mandible and may be associated with TMJ dislocation.
how do transverse processes end in typical cervical vertebrae and clinical significance of this for palpating carotid pulse?
Anterior and posterior tubercles
common carotid artery can be compressed against anterior tubercle of transverse process of C6 vertebra- known as carotid tubercle, below bifurcation at C4 vertebra where it is more likely that a drop in BP and HR might occur
can also control bleeding of artery by compression here
why might slight dislocations of C vertebrae not damage SC?
as large vertebral canal
what may cause a fractures of the dens?
horizontal blow to head, or complication of osteopenia
can injure SC- quadriplegia
may injure medulla of bstem, causing death
when might hyperflexion of cervical region occur?
head on car collisions
rupture of lower intervertebral discs (C5/C6 and C6/C7) resulting in compression of spinal roots C6 and C7
Pain is felt in the neck, shoulder, arm and hand
When does whiplash injury occur?
rear-end car collisions
may tear A and P longitudinal ligaments, disc dislocation, fracture spinous processes, neck muscle injury, blood vessel injury
what is a broken neck?
Compression of the cervical spine against the shoulder
May involve spinal cord damage
Partial or complete paralysis
Most common at C2, C6 and C7
The most fatal injuries occur in the upper part of the spine (C1 or C2)
why does leakage of CSF tend to occur with cranial base fractures?
the 2 dural layers are firmly attached and difficult to separate from the bones, hence a fracture usually tears the dura.
plane of structural weakness at dura-arachnoid junction
when might a patient present with a pulsating exophthalmos?
fracture of cranial base: internal carotid artery may be torn, producing an arteriovenous fistula within the sinus, arterial blood rushes into cavernous sinus, enlarging it and forcing retrograde blood flow into venous tributaries, especially opthalmic veins.
which bone surrounds the external auditory meatus?
temporal bone (tympanic part)