EOMs Basic Anatomy Flashcards
what protects the eyes?
deep bony orbits
what shape is the orbit?
roughly pyramidal in shape
what is the thick, bony roof composed of?
frontal bone & a portion of the lesser wing of sphenoid
what is the lateral wall composed of?
zygomatic bone & greater wing of sphenoid
what is the thin, medial wall composed of?
maxillary, lacrimal, ethmoid, & sphenoid bones
what walls of the orbit are parallel to each other?
medial walls
the plane of lateral wall in each orbit is how many degrees from the sagittal plane formed by the medial wall?
45°
the geometry of the orbital bones requires that both globes have to be?
partially adducted in primary gaze
what is the maintenance of eye position in primary gaze requires a constant steady-state resting level of tension in all the EOMs?
tonus
what are the three major foramina at the apex of the bony orbit?
optic foramen, superior & inferior orbital fissures
where is the optic foramen found?
within the lesser wing of sphenoid & orbital apex
what runs through the optic foramen?
CN2 & ophthalmic artery
what is the 7th skeletal muscle in the orbit & what is it’s function
LPS → elevates palpebral fissure
where do the 4 recti muscle originate?
common tendinous ring (annulus of Zinn)
what is the progressive spiral that the recti muscles form & where is it located?
Spiral of Tillaux → around corneal limbus
rank the recti from closest to furthest from to the limbus
medial, inferior, lateral, superior
what does the muscle-scleral insertion line look like?
horseshoe configuration
where does the superior oblique originate?
arises from sphenoid bone just superior to tendinous ring
where does the inferior oblique originate?
from orbital floor, just lateral to the lacrimal fossa
what are the anatomic & physiologic origins & insertion of the superior oblique?
anatomic → lesser wing of sphenoid
physiologic → trochlea
inserts at superior, posterior, lateral globe
origin & insertion of medial rectus
common tendinous ring & optic nerve sheath → anterior globe
origin & insertion of lateral rectus
common tendinous ring & greater wing of sphenoid → anterior globe
origin & insertion of superior rectus
common tendinous ring & optic nerve sheath → superior, anterior globe
origin & insertion of inferior rectus
common tendinous ring → inferior, anterior globe
origin & insertion of inferior oblique
medial maxillary bone → inferior, posterior, lateral globe
blood supply to the lateral rectus
lacrimal artery & lateral muscular branch of ophthalmic artery
blood supply to the medial rectus
medial muscular branch of the ophthalmic artery
blood supply to the superior rectus
lateral muscular branch of the ophthalmic artery
blood supply to the inferior rectus
medial muscular branch of the ophthalmic artery
blood supply to the inferior oblique
infraorbital artery & medial muscular branch of ophthalmic artery
blood supply to the superior oblique
superior muscular branch of the ophthalmic artery
innervation of lateral rectus
CN6
innervation of medial rectus
CN3 inferior branch
innervation of superior rectus
CN3 superior branch
innervation of inferior rectus
CN3 inferior branch
innervation of superior oblique
CN4
innervation of inferior oblique
CN3 inferior branch
innervation of LPS
CN3
what helps keep the eyelid raised along with LPS?
Muller’s muscle
origin & insertion of Muller’s
underside of LPS → superior tarsal plate of lid
innervation of Muller’s
from the sympathetic nervous system
what syndrome is associated with Muller’s?
Horner’s
which EOM is closest to the limbus
medial
