Skull, Orbital Bones, CT Flashcards
where is the anterior and posterior crest of lacrimal sac fossa
anterior: maxillary bone
posterior: lacrimal bone
where is the inferior orbital fissure located
lateral wall + floor
what bones make up the middle cranial fossa
temporal bones
what goes through the foramen spinosum
middle meningeal artery
which wall of the orbit is the strongest
lateral wall
what stabilize the muscle + prevents overaction of muscles
muscle pulley/check ligament
what houses the pituitary gland
sella turcica
what does V1 go through
superior orbital fissure
what is the optic canal
transmits the ON and ophthalmic artery
what bones make up the lateral wall
zygomatic (anterior), greater wing of sphenoid body (posterior)
what bones make up the roof of the orbital wall
frontal bone + lesser wing of the sphenoid bone
what holds the sinuses
ethmoid air cells
what is the orbital plate
medial orbit; holds the orbit on both sides
what cells lighten the skull
ethmoid air cells
where do tears drain from the eye
fossa of lacrimal sac
what is continuous w/ periorbita at margins of orbit
orbital septum
what is the thinnest bone
ethmoid orbital plate (lamina papyrace)
tenons capsule
surrounds the globe, barrier to infection from globe/eyeball
what makes up the medial portion of orbit
ethmoid bone
what provides communication between pterygopalatine/ temporal fossa and orbit
inferior orbital fissure
what bones make up the medial wall of the orbit
frontal process of maxilla, lacrimal bone, orbital plate of the ethmoid bone
placement of visual evoked potential electrodes (VEP):
3 cm above inion, measures electrical potential made by the visual system to ensure info is getting to occipital lobe
-used for VAs or if someone faking VFL
frontal sinus
above the eyes in frontal bone
what makes up the body central portion of brain
sphenoid body
what makes up the posterior fossa
occipital lobe + cerebellum
foramen magnum
the hole in the base of the skull through which the spinal cord passes.
what forms the posterior fossa
occipital bone
what drains the tears into the nose
nasolacrimal canal - located in lower portion
how can there be an infection in ethmoid
bacteria can eat through bone into orbit
what goes through the SOF above the CTR
lacrimal nerve, frontal nerve, trochlear nerve, superior ophthalmic vein –> drains globe
what does the infraorbital canal open into
infraorbital foramen
supraorbital notch
vessels + nerves pass through
what are the landmarks of the orbital roof
lacrimal gland fossa, trochlea, supraorbital notch, supratrochlear notch
ethmoid sinus
medial to eyeballs, thinnest
what is the most posterior portion of the medial wall
body of the sphenoid bone, next to optic canal
orbital fat
adipose tissue fills in the rest of orbit
maxillary sinus
inferior eyes, largest, trauma to eye will blow out orbital floor + bone, tissue, muscles can enter the sinus
what is the attachment for EOMs to eye
tenons capsule
common tendinous ring and oculomotor foramen
circular and of CT, origin of all 4 rectus muscles
what supplies circulation to globe + surroundings
ophthalmic artery
what goes through the SOF
everything in cav sin (CN5 (V1), 4, 6)
what forms the sella turcica
sphenoid body
anterior + superior skull
frontal bone
what are sinuses
air filled cavities within four of the bones surrounding the orbit
orbital CT
lines, separates + anchors orbital structure
what is the majority of the medial wall
orbital plate of the ethmoid bone
side portion of head
parietal bones
what is the SOF between
lateral wall + roof
where is the greater wings of the sphenoid located
more laterally
CN6 palsy with papilledema
increase in ICP pushes down on brainstem, stretching CN6 @ 90 degree turn –> papilledema + double vision
what does a blow fracture cause
numbness of upper cheek (V2), diplopia, swelling, ecchymosis (bruise)
inion
external occipital protuberance
what does CN6 pass
goes over the petrous portion of temporal bone
where is a blow out fracture located and why
inferior floor of orbit
due to the groove, canal foramen
what are the landmarks of the lateral wall
SOF, IOfissure,
what is the SOF formed by
gap between greater + lesser wings of the sphenoid
what foramens are in the greater wings
foramen rotundum, foramen ovale, foramen spinosum
what is behind the orbital plate of ethmoid bone
ethmoid bone + nose
through SOF and CTR
oculomotor nerve, nasocilliary nerve, abducens nerve
orbital cellulitis
infection of orbit due to thin walls of ethmoid sinuses or eyelids, fungal infections. most severe (eats through bone), once in orbit there is a direct pathway via fissure to the brain
where is the infraorbital canal located
within the infraorbital in the maxilla
what portion of the temporal bone is more anterior
squamous portion; makes up most of the lateral portion
suspensory ligament of lockwood
holds up orbit (hammock) inferiorly, CT between 2 muscles
what are the landmarks of the orbit floor
IOfissue, IOgroove, IOforamen
periorbita
thickens posteriorly to form CTR
dimensions of orbital margins
2cm horizontal, 3.5 cm vertical, 4.5 cm depth
what goes through the foramen ovale
mandibular branch (CN5) V2
what is the CT between conj + episclera
tenons capsule
where is the lesser wing located
anterior + superior, smaller
preseptal cellulitis
in front of septum, not as serious, protected from brain, usually from a hordeolum, eyelid infection, usually goes away or can burst inside of eyelid –> treat w/ oral abx
what goes through the foramen rotundum
maxillary nerve (CN5) V3
what is the SOF formed by
gap between the greater and lesser wing
what is between the body and lesser wing
optic foramen/canal
what are all the orbital bones and how many of each
frontal, maxillary (2), zygomatic (2), sphenoid, ethmoid, lacrimal (2), palatine (2)
orbital septum
- 360 degree from rim of orbit to tarsal plate
- keeps orbital fat in place
- prevents infection from eyelids back
what separates the lateral wall and floor of orbit
inferior orbital fissure
what is the optic canal formed by
hole between body + lesser wing
what covers the bone
periorbita
what bones make up the floor of the orbit
maxillary (main, medial) , zygomatic (lateral), palatine (posterior)
maxilla location
medial wall but continuation from the floor
supratrochlear notch
nerves + vessels pass through
sphenoid sinus
- medial + posterior to eyeballs
- within body of sphenoid, can surround the optic canal
- close to many structures - pituitary gland
what carries nerves + blood to bone
periorbita
where oes the infraorbital nerve (branch of maxillary nerve V2) exit the orbit?
infraorbital foramen
what is trochlea
u- shaped cartilage which anchors SO muscle
what forms the anterior cranial fossa
frontal bone; where front of brain sits
paranasal sinuses location
on all sides besides lateral sides
what goes through the optic canal + CTR
optic nerve, ophthalmic artery
where is the fossa for lacrimal gland located
roof laterally
petrous portion of the temporal bone does what
houses most of middle + inner ear system
what do olfactory nerves go through
horizontal cribriform plate- olfactory nerves come through here + go to brain
lateral portion of brain
temporal bones
connection of muscle onto bone
muscle pulley/check ligament
what is the optic foramen
opening to the optic canal
through inferior orbital fissure below the CTR
infraorbital nerve (CN5 sensory), infraorbital artery, inferior ophthalmic vein
where does the ON exit the orbit
optic foramen
what are the symptoms of orbital cellulitis
proptosis, diplopia (muscles), fever, *unique to orbital (not seen w/ preseptal)
