Superior oblique muscle
Musculus obliquus superior bulbi oculi
- Latin synonym: Musculus obliquus superior
- Related terms: Superior oblique
Definition
The obliquus oculi superior (superior oblique muscle) is a fusiform muscle, placed at the upper and medial side of the orbit.
Origin: Annulus of Zinn at the orbital apex, medial to optic canal
Insertion: Outer posterior quadrant of the eyeball
Artery: Lateral muscular branch of the ophthalmic artery
Nerve: Trochlear nerve
Action: Primary: intorsion. secondary: abduct (laterally rotate) and depress the eyeball
Description:
The obliquus oculi superior arises immediately above the margin of the optic canal, above and medial to the origin of the Rectus superior, and, passing forward, ends in a rounded tendon, which plays in a fibrocartilaginous ring or pulley (trochlea of superior oblique muscle) attached to the trochlear fovea of the frontal bone.
The contiguous surfaces of the tendon and ring are lined by a delicate mucous sheath (tendinous sheath of superior oblique), and enclosed in a thin fibrous investment. The tendon is reflected backward, lateralward, and downward beneath the Rectus superior to the lateral part of the bulb of the eye, and is inserted into the sclera, behind the equator of the eyeball, the insertion of the muscle lying between the Rectus superior and Rectus lateralis.