Cranial Fossae and the Eye Flashcards
what is the only bone made completely out of chondrocranium?
ethmoid
all nerves and vessels going in and out of the cranial vault go through what?
chondrocranium
what is the only thing that pierces through the dermatocranium of the facial skeleton?
trigeminal nerve
what cranial bone is in the anterior cranial fossa?
ethmoid
what cranial bones are in the middle cranial fossa?
sphenoid and temporal
what cranial bone is in the posterior cranial fossa?
occipital
what growth plates does the face lengthen from?
spheno-ethmoid synchondrosis, midsphenoid synchondrosis and spheno-occipital synchondrosis
what is dwarfism caused by?
premature fusing of growth plates
what is considered the ‘center piece’ of the skull?
sphenoid
what is the greater wing of sphenoid made out of and what does it look like?
dermatocranium, flares out
what is the lesser wing of sphenoid made out of and where is it?
chondrocranium, interior
what are the medial and lateral pterygoid plates made out of?
dermatocranium
what are our chewing apparatuses made out of?
dermatocranium with some chondrocranium
describe the sella turcica
tuberculum sellae, hypophyseal fossa, dorsum sellae, saddle-like frame, made of tight dura, contains pituitary
what are the 2 grooves on either side of the sella turcica called?
carotid grooves
what does the pterygopalatine fossa house?
sphenopalatine/pterygopalatine ganglion
what foramen are within the sphenoid?
superior orbital fissure, optic canal, foramen rotundum, foramen ovale, foramen spinosum
where do the superior orbital fissure and optic canal lead to?
orbit
what do foramen ovale and foramen spinosum lead to?
drop into infratemporal fossa
what does the foramen rotundum and pterygoid canal lead to?
sphenopalatine recess
what bone contains crista galli and cribiform?
ethmoid
what is the main drainage for the brain?
sigmoid sinus
what does the sigmoid sinus become in the jugular foramen?
internal jugular
what is within the internal acoustic meatus?
facial, superior vestibular, inferior vestibular, cochlear, Bill’s bar
what is Bill’s bar
bone that separates facial from rest of nerves
what opens into the orbit?
superior and inferior orbital fissure and optic canal
what is within the superior orbital fissure?
lacrimal nerve, frontal nerve, trochlear nerve, superior and inferior branches of oculomotor nerves, nasociliary nerve, abducens nerve and superior opthalamic vein
what is within the optic canal?
optic nerve and opthalamic artery
what is in the inferior orbital fissure?
zygomatic nerve and infraorbital nerve
what opens out of the orbit?
supraorbital foramen, nasolacrimal canal/duct
what is in the supraorbital foramen?
supraorbital VAN
what passes in the floor of the orbit?
infraorbital foramen
what is in the infraorbital foramen?
infraorbital VAN
what is the superior tarsal plate made out of?
firm low grade cartilage
describe the conjunctiva
membrane on inner eyelids and outer eyeballs, lubricates eyeball, moves with and is affixed to eyeball, part of gut tube (brings in photons)
what muscle lifts the eyelid?
levator palpebrae superioris
what is affixed to the levator palpebrae superioris?
superior tarsal muscle
what does the superior tarsal muscle do?
lifts eyelid when it relaxes eye, can’t keep eyes open, smooth mm, autonomic control
what does the tarsal gland produce?
meibum
what is meibum?
oily substance secreted by tarsal gland that thickens tears
what causes styes?
blockage of tarsal gland
describe the route of a tear
superior lateral lacrimal gland leaks tear onto surface of eye into conjuctiva, eye closes faster on lateral side compared to medial causing tear to sweep more midline towards canaliculi and is taken up by nasolacrimal duct
what does the inferior nasal meatus drain?
tears
what is within the common tendinous ring?
optic canal, abducens, superior and inferior oculomotor, nasociliary nerve
where do the 4 recti muscles originate from?
common tendinous ring
what are the extraocular muscles?
superior, medial, lateral and inferior rectus, superior and inferior oblique
what extraocular muscles arise from the lesser wing of sphenoid?
superior oblique and levator palpebrae
what does the inferior oblique arise from?
maxilla lateral to nasolacrimal foramen
what do the obliques attach onto?
posterior aspect of globe of eye
what do the recti attach onto?
anterior aspect of globe of eye
where does oculomotor split into its 2 divisons?
cavernous sinus
what extraocular muscles does the superior division of oculomotor innervate?
superior rectus, levator palpebrae superioris
what extraoculomotor muscles does the inferior division of oculomotor innervate?
inferior rectus, medial rectus, inferior oblique
what extraocular muscle does the trochlear nerve innervate?
superior oblique
what extraocular muscle does the abducens nerve innervate?
lateral rectus
describe the optical axis
points forward where pupil is pointed during rest
describe the orbital axis
orientation of bones and muscles points later and out
what degree of rotation do they eyes have on the transverse plane away from each other
25 degrees
what prevents the inferior and superior rectus muscles from having purely sagittal actions?
misalignment of the axis of they eye and axis of the orbit
what eye movement does the lateral rectus perform?
abducts eye
what eye movement does the medial rectus perform?
adducts eye
what eye movement does the inferior oblique perform?
moves eye up and out
what eye movement does the superior rectus perform?
moves eye up and in
what eye movement does the superior oblique perform?
moves eye down and out
what eye movement does the inferior rectus perform?
moves eye down and in
describe intorsion
top of eyeball moves in towards nose (superior oblique and rectus)
describe extorsion
top of eyeball moves out away from nose (inferior oblique and rectus)
what does intorsion and extorsion allow?
rotate eyeballs to keep planar when tilting head
what muscles assist in intorsion?
superior rectus and oblique
what muscles assist in extorsion?
inferior rectus and oblque
how does the orbit get its blood supply?
opthalamic artery (1st branch off internal carotid)
what artery dives into optic erve?
central artery of retina
what drains the eye?
superior opthalamic
what do zonular fibers do?
suspend lens in place
what are the ciliary body and muscles continuous with?
choroid layer
the retina is?
photosensitive
the choroid layer contains?
vasculature
what is the sclera made out of and what is it continuous with?
connective tissue and collagen, continuous with cornea
what does the cornea do?
focuses primary lens far away bending light on retina
what does the lens do?
changes shape
what do the anterior and posterior chambers contain?
aqueous humor
what does the iris divide?
anterior and posterior chamber
what does the vitreous body contain?
vitreous humor
what does vitreous humor do?
provide structure to eye
what part of the eye is a former artery?
hyaloid canal
what does the fovea centralis contain?
cones
what part of the eye makes aqueous humor?
ciliary process
what does the iris do?
controls amount of light entering eye
what feeds the cornea and lens?
aqueous humor
what drains back into the venous of the eye?
canal of schlemm
what 2 muscles make up the iris?
sphincter pupillae and dilator pupillae
what part of the eye is the cornea primarily responsible for focusing?
anterior eye
describe what happens to the eye with far vision?
thin lens is pulled flat to bend less light accommodating for far vision
describe what happens to the eye during near vision
thick lens bends light to focus it onto fovea centralis
what happens during far accomodation?
ciliary body relaxes, zonular fibers are taught, vitreous body expands (pushes fully onto sclera), pupils dilate, lens is flattened
what happens during near accomodation?
ciliary body contracts, zonular fibers relax, vitreous body is compressed, pupil contracts, lens relaxes and is rounded
only what type of innervation goes to ciliary body?
parasympathetic
what happens during hyperopia?
lens gets stiffer, ciliary body and muscles get weaker and are not bending light enough
what happens during myopia?
too much light is bent, eye is too long or lens is too thick
what part of they eye contains the greatest number of photosensitive cells?
macula
what are rods and cones?
highly derived cilia
rods are sensitive to?
light
cones are sensitive to?
color
describe what rods are used for?
night vision contrast and light intensity
what are cones used for?
color, they are only activated at a particular wavelength and need a large amount of light to operate
describe the neuroanatomy of the eye from the front to the back
vitreous body, nerve fibers to optic nerve, retinal support cells, rod and cone nuclei, rod and cone outer segments, pigment epithelium, choroid layer, sclera
what does the pigment epithelium do?
absorb light
what are the rods and cone stimulated by?
photons
what is the optic disc?
the blind spot, all of the optic nerve coalesces back to
what light is absorbed most?
blue
why are men more likely to be red-green colorblind than women?
gene is located on x chromosome
what is the superior colliculus responsible for?
blinkng reflex
what does the medial part of the optic chiasm do?
gather information from lateral part of vision of opposite eye
what does the lateral part of the optic chiasm do?
gather information from medial part of vision of opposite eye
what will cross over in the optic chiasm and what will not?
medial will cross over, lateral will not
what is responsible for the startle reflex?
inferior colliculus
when do the growth plates in the skull stop growing?
early adulthood
the chondrocranium grows similarly to what?
long bones
where within the sella turcica does the pituitary sit?
hypophyseal fossa
what attaches at the pterygoid hammulus?
tensor veli palatini
what bone is the pterygoid hamulus part of?
sphenoid
where is the pterygomandibular raphe?
pterygoid hook to mandible
what bones make up the orbit?
frontal, sphenoid, zygomatic, maxilla, ethmoid, palatine and lacrimal
what does the superior orbital fissure create a passage between?
cranial vault and orbit
what does the inferior orbital fissure create a passage between?
facial skeleton and orbit
what vessel passes through the inferior orbital fissure?
inferior opthalamic vein
what lines the orbit?
periorbita
what is the only eye muscle that does not arise from the back of the orbit?
inferior oblique
where is the pterygoid plexus?
within the infratemporal fossa
what forms the choroid layer?
posterior ciliary arteries
what humor is in the anterior chamber?
aqueous
what humor is in the posterior chamber?
vitreous
why is the sclera white?
collagen
what is normal vision called?
emmetropia
what is nearsightedness called?
myopia
what is farsightedness called?
hyperopia
what lens is used to correct myopia?
concave to bend light more
what lens is used to correct hyperopia?
convex to bend light less
what parts of a rod or cone is stimulated by photon?
outer segment
what are the 3 cone colors?
red, green and blue
