Orbit Flashcards
What 4 muscles insert onto the common tendinous ring?
All the rectus muscles: Sup, Inf, Lat, Med.
What are the muscles in the upper and lower eyelids called? (consistently sympathetically innervated when awake)
superior and inferior tarsal muscles - Think Horner’s syndrome = droopy eyes
What is Horner’s Syndrome and what are symptoms?
Loss of sympathetic innervation to the head. Droopy eyelids (tarsal plates) and constricted pupils (loss of dilation ability)
Also, bulging eyes cause tarsal muscles hold them in a little.
Within the eye, what space do tears constitutively drain into?
conjunctival sac
What is the medical term for droopy eyelids?
Ptosis
Most of the extrinsic eye muscles function to move the globe. What is the exception and what does it do?
Levator Palpebrae Superioris- raises the eyelid.
Are the muscles of the eye innervated by BE fibers?
NO! GSE!
Name the neurovasculature that enters the orbit ABOVE the common tendinous ring.
Lacrimal Frontal (V1 branches)
Trochlear (CN VII)
Superior Opthalmic Vein.
LAZY FRENCH TARTS
Name the neurovasculature that enters the orbit WITHIN the common tendinous ring.
Superior Occulomotor (CN III)
Nascilliary (V1)
Inferior Occulomotor (CN III)
Abducent (CN VI)
SIT NAKED IN ANTICIPATION
What is the only structure that comes out below the tendinous ring?
Inferior Opthalmic Vein
The frontal nerve terminates as 2 branches. Name them.
Which is more MEDIAL?
Supratrochlear and Supraorbital.
Supratrochlear is more medial.
What runs with the nasocilliary nerve?
Opthalmic Artery
What branches does the Opthalmic artery give off?
Anterior and Posterior Ethmoidal branches.
Remember the nasocilliary nerve does the same.
What nerve innervates the Lateral Rectus?
Abducent (LR6)
What nerve innervates the Superior Oblique?
Trochlear (SO4)
The superior branch of the occulomotor nerve innervates what muscles?
The superior rectus and the legator palpebrae superioris.
What muscles does the inferior branch of Occulomotor (CN III) innervate?
Medial, Inf rectus, and Inferior Oblique.
The drug Pylocarpine does what?
(pupil constriction) because it is a parasympathetic mimetic drug.
The drug Atropine does what?
Causes Myosis. (dilated pupil) because it blocks parasympathetic activation of constrictor muscles.
GSA fibers to the globe are carried by what nerve?
What “helper” nerve carries these fibers from the nasocilliary nerve to the globe?
Nasocilliary (V1)- via the LONG CILLIARY NERVE
Parasympathetic innervation to the orbit is carried by what nerve?
What ganglion do the preganglionics run to?
What nerve takes postganglionics to the orbit from the ganglion?
Occulomotor (III) carries parasympathatic innervation to the orbit. Preganglionics synapse in the ciliary ganglion and postganglionics reach the globe via the SHORT CILIARY NERVE.
What is accommodation?
Walk into a dark room, pupils dilate. Walk into a bright room, pupils constrict.
Belladonna is what?
A drug like Atropine that inhibits parasympathetic innervation to the eye. The pupils are highly dilated.
What branch of the Opthalmic artery penetrates the Optic nerve? Why is it important?
The central retinal artery branches off Opthalmic and pierces the Optic nerve. It is the SOLE SUPPLY of blood to the retina. Lose it, go blind.
