orbit cavity Flashcards
what is the orbit bounded by?
ethmoid & maxillary paranasal sinuses
levator palpebrae superioris
lifts the superior eyelid, innervated by CN III
orbicularis oculi
closes the eyelid
conjunctiva
transparent mucous membrane that covers the inner surface of the eyelids and anterior surface of the eyeball, most infected (pink eye)
lacrimal apparatus
keeps the surface of the eye moist, consist of glands and ducts that drain lacrimal fluid into nasal cavity
lacrimal gland
tears
lacrimal ducts
convey fluid to conjunctival sac
lacrimal canaliculi
passage that conveys lacrimal fluid to nasal cavity
what nerve is lacrimal production stimulated by?
parasympathetic CN VII (facial nerve)
what are the 7 extra-ocular muscles of the orbit?
levator palpebrae superioris, 4 recti (superior, inferior, medial, lateral), 2 obliques (superior, inferior)
common tendinous ring
origin of the 4 recti, surrounds the optic canal
what is the anchor point and insertion for all extra-ocular muscles?
orbital bone and side of eyeball
what is the primary action of the recti muscles?
elevation, depression, adduction, abduction of eyeball
superior oblique muscle
posterior side, abducts and depresses pupil (look out and down) CN III
inferior oblique
abducts and elevates pupil (look out and up) CN III
superior rectus
elevates and adducts pupil (look up and in) CN III
inferior rectus
depresses and adducts pupil (look down and in) CN III
medial rectus
adducts pupil (look in) CN III
lateral rectus
abducts pupil (look out) CN VI
general sensory
CN V I nerves, skin of eyelid
special sensory
CN II for vision
branchial motor
CN VII to orbicularis oculi (closure of eyelids)
somatic motor
CN III to levator palpebrae superioris, superior rectus, inferior rectus, medial rectus, and inferior oblique muscles
CN IV to superior oblique
CN VI to lateral rectus
what arterial blood supply does the orbit receive?
ophthalmic artery off internal carotid artery
the blockage of what artery results in instant blindness?
central retinal artery
