superior oblique muscle superior oblique muscle the superior oblique muscle, or obliquus oculi superior, is a fusiform muscle originating in the upper, medial side of the orbit (i.e. from beside the nose) which abducts, depresses and internally rotates the eye. it is the only extraocular muscle innervated by the trochlear nerve (the fourth cranial nerve). for other muscles called "oblique", see oblique muscle. superior obliquerecti muscles: 2 = superior, 3 = inferior, 4 = medial, 5 = lateraloblique muscles: 6 = superior, 8 = inferiorother muscle: 9 = levator palpebrae superiorisother structures: 1 = annulus of zinn, 7 = trochlea, 10 = superior tarsus, 11 = sclera, 12 = optic nervesagittal section of right orbital cavitydetailsoriginsphenoid bone at the orbital apex, medial to optic canalinsertionouter posterior quadrant of the eyeballarterylateral muscular branch of the ophthalmic arterynervetrochlear nerveactionsprimary action is intorsion (medial rotation); secondary actions are to abduct and depress the eyeball (i.e. it makes the eye move outward and downward)identifierslatinmusculus obliquus superior bulbita98a15.2.07.016ta22048fma49039anatomical terms of muscle structure