facial bones Flashcards
find and label anatomy of skull bones
what are the 4 sinus found in the skull/face
- frontal sinus
- ethmoidal sinus
- sphenoidal sinus
- maxillary sinus
describe how the 4 sinus structures sit in the skull from anterior to posteriro
anteriorly sits the frontal sinus ethmoidal sinus and maxillary sinus (going in that order from top to bottom)
then the sphenoidal sinus sits posterior to the ethmoid sinus slightly inferiorly
what do you call the structure that separates the right and left frontal sinuses
intersinus septum
what is the wall of the sinus cavities covered in and why
- mucus
- keeps tissue moist and healthy, and traps bacteria
how does the mucus in the sinus help the air that passes through it down to the lungs
- helps humidify and filter the air
the sinuses also help the voice resonate
what is sinus the latin word for
curve or fold
(referred to system of hollow cavities in anatomy)
where is the glabella, nasion, acanthion and mental point found on the face/skull
glabella = point between eyebrows above nose
nasion = beginning of nose bridge below glabella
acanthion = cupids bow (beneath nose)
mental point. = front / tip of jaw
what are the 5 positioning lines of the face
- glabellomeantal line
- orbitomeatal line
- infraorbitomeatal line
- acanthiomeatal line
- mentomeatal line
what is the Occipitomental view best for viewing
- upper and middle 3rd of face
- orbital margins
- frontal sinus
- zygomatic arches
- maxillary antra/sinus
how should you raise the chin of the patient for an OM pa view
- raise the chin against the IR so that the OM line is 45 degrees cranial from the perpendicular line to the IR
- makes the mentomeatal line exactly perpendicular to the IR
what is a an OM 30 good for seeing
- orbital margins (not orbits whole)
- zygomatic arches
- mandible
for a PA mandible view, which positioning line should be parallel to the floor
- orbitomeatal line
- and the interpupillar line
where is the beam centred for a PA mandible view
- point in the midline between the angles of mandible
how can you tell if the head is rotated during a veiw
- check that the external auditory meatus (EAM) is equidistant from the detector
how does the tilting of the head differer from a PA orbital view and a PA OM view
- PA orbital view only requires 35 degree tilt from horizontal instead of 45
how should you collimate for PA orbital and where do you centre
- letter box collimation
- centre midpoint between orbits
what should you see on a PA orbital view
- round not oval orbits
- petrous ridge projected below the orbits (found in the lower 3rd of maximally sinus)
what is a blow out fracture of the orbit
- a blow to the globe causes increased intra-orbital pressure
- this causes fracture in thin plate of bone forming the floor of the orbit (also the roof of the maxillary antrum)
- some of the orbital contents e.g fat and muscle, herniate down into maxillary sinus
what is a radiographic feature of a blow out fracture in the orbits
- soft tissue formed teardrop or polypoid mass in the roof of the maxillary antrum
asses the zygoma by following the elephants trunk
find a diagram and identify the frontal process, orbital process and body of the zygomatic bone
what is the name of the foramen found in the zygomatic bone
zygomaticalfacial foramen
if you spot a black eyebrow sign in a facial xray what can this indicate
- free air due to blow out fracture
if you spot air-fluid level in the maxillary sinus, what can this indicate
blood due to fracture
what are some direct radiological signs of a facial fracture
- non anatomic linear lucencies
- cortical defect/ widening of suture
- bone fragments overlapping causing double density
- asymmetry of face
what are some indirect signs of facial fractures
- soft tissue swelling
- periorbital or intracranial air
- fluid in paranasal sinus
because the mandible is a ring of bone, what does this mean about its fractures
likely to fracture at more than one point
what is a quadripod or tripod fracture, also known as zygomaticomaxillary complex fracture
fracture to :
- zygomatic arch
- inferior and lateral orbital rim
- anterior and posterior maximally sinus walls
overall, separates the zygoma wall at all its attachments from the rest of the face
difference between OM and OM 30 scan
OM = orbitalmeatal line 45 degrees cranially to receptor and the tube is perpendicular to receptor
OM 30 = same positioning as OM but the tube is angled 30 degrees caudally to the receptor
if an examination is purely done to exclude foreign bodies from the orbits, what type of collimation should be done
letter box collimation
- reducing dose by not scanning what is not required
during an OM orbital view, where is the petrous ridge seen
in the lower 3rd of the maxilla
what 6 bones are the orbits made of
lacrimal
ethmoid
palatine
zygomatic
frontal
sphenoid
find a diagram and label the 7 bones of the orbits
know how to take OM, OM 30, PA orbit and PA mandible
find and label facial/skull bones, skull sutures
