Musculus obliquus superior

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).Eye movement of lateral rectus muscle, superior viewEye movement of medial rectus muscle, superior viewEye movement of inferior rectus muscle, superior viewEye movement of superior rectus muscle, superior viewEye movement of superior oblique muscle, superior viewEye movement of inferior oblique muscle, superior viewAnterior viewNerves of the orbit. Seen from above.Dissection showing origins of right ocular muscles, and nerves entering by the superior orbital fissure. 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). The superior oblique muscle loops through a pulley-like structure (the trochlea of superior oblique) and inserts into the sclera on the posterotemporal surface of the eyeball. It is the pulley system that gives superior oblique its actions, causing depression of the eyeball despite being inserted on the superior surface. The superior oblique arises immediately above the margin of the optic foramen, superior and medial to the origin of the superior rectus, and, passing forward, ends in a rounded tendon, which plays in a fibrocartilaginous ring or pulley attached to the trochlear fossa of the frontal bone.