Week 4: Extra-Ocular and Intrinsic Muscles of the Eye

Lateral rectus

Common tendinous ring

Origin of Lateral Rectus

Lateral side of eyeballs

Insertion of Lateral rectus

Abducts eyes

Action of Lateral Rectus

Abducent nerve (CN VI)

Innervation of Lateral Rectus

Superior rectus

Common tendinous ring

Origin of Superior rectus

Superior and central part of eyeballs

Insertion of Superior rectus

Elevates, adducts, and intorts eyes

Action of Superior rectus

Oculomotor nerve (CN III)

Innervation of Superior rectus

Inferior rectus

Common tendinous ring

Origin of Inferior rectus

Inferior and central part of eyeballs

Insertion of Inferior rectus

Depresses, adducts, and extorts eyes

Action of Inferior rectus

Oculomotor nerve (CN III)

Innervation of Inferior rectus

Medial rectus

Common tendinous ring

Origin of Medial rectus

Medial side of eyeballs

Insertion of Medial rectus

Adducts eyeballs

Action of Medial rectus

Oculomotor nerve (CN III)

Innervation of Medial rectus

Levator palpebrae superioris

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

Origin of Levator palpebrae superioris

Superior tarsus and skin of upper eyelid

Insertion of Levator palpebrae superioris

Elevates superior eyelid

Action of Levator palpebrae superioris

Oculomotor nerve (CN III)

Innervation of Levator palpebrae superioris

Inferior oblique

Maxilla in floor of orbit

Origin of Inferior oblique

Eyeballs between inferior and lateral recti

Insertion of Inferior oblique

Elevates, abducts, and extorts eyes

Action of Inferior oblique

Oculomotor nerve (CN III)

Innervation of Inferior oblique

Superior oblique

Sphenoid bone, superior and medial to common tendinous ring in orbit

Origin of Superior oblique

Eyeball between superior and lateral recti via tendon that passes through trochlea

Insertion of Superior oblique

Depresses, abducts, and intorts eyes

Action of Superior oblique

Trochlear nerve (CN IV)

Innervation of Superior oblique

Dilator pupillae

Outer margins of iris

Origin of Dilator pupillae

Sphincter pupillae

Insertion of Dilator pupillae

Pupil dilation

Action of Dilator pupillae

Long ciliary nerves (sympathetics)

Innervation of Dilator pupillae

Sphincter pupillae

Encircles iris

Origin and Insertion of Sphincter pupillae

Pupil constriction

Action of Sphincter pupillae

Short ciliary nerves (parasympathetics)

Innervation of Sphincter pupillae