Orbit 6/21

Question 1

Levator Palpebrae Superioris

Answer 1

Origin:
Lesser wing of sphenoid bone, superior and anterior to optic canal

Insertion:
Superior tarsus and skin of superior eyelid

Innervation:
Occulomotor nerve; deep layer (superior tarsal muscle) supplied by sympathetic fibers

Action:
Elevates superior eyelid

Question 2

Superior Oblique (SO)

Answer 2

Origin:
Body of sphenoid bone

Insertion:
Tendon passes though trochlea to insert into sclera, deep to SR

Innervation:
Trochlear Nerve (CN IV) 

Action:
Abducts, depresses, and rotates eyeball medially (Intorsion)

Question 3

Inferior Oblique

Answer 3

Origin:
Anterior part of floor of orbit

Insertion:
Sclera deep to lateral rectus muscle

Innervation:
Oculomotor Nerve (CN III)

Action:
Abducts, elevates, and rotates eyeball laterally (extorsion)

Question 4

Superior Rectus (SR)

Answer 4

Origin:
Common tendinous ring

Insertion:
Sclera just posterior to corneoscleral junction

Innervation:
Oculomotor nerve (CN III)

Action:
Elevates, adducts, and rotates eyeball medially (Intorsion)

Question 5

Inferior Rectus (IR)

Answer 5

Origin:
Common tendinous ring

Insertion:
Sclera just posterior to corneoscleral junction

Innervation:
Oculomotor Nerve (CN III)

Action:
Depresses, adducts, and rotates eyeball laterally (Extorsion)

Question 6

Medial Rectus (MR)

Answer 6

Origin:
Common tendinous ring

Insertion:
Sclera just posterior to corneoscleral junction

Innervation:
Oculomotor Nerve (CN III)

Action:
Adducts eyeball

Question 7

Lateral Rectus (LR)

Answer 7

Origin:
Common tendinous ring

Insertion:
Sclera just posterior to corneoscleral junction

Innervation:
Abducent Nerve (CN VI)

Action:
Abducts eyeball