Physiology

Incyclotorsion is a term applied to the inward, torsional (rotational) movement of the eye, mediated by the superior oblique

Superior oblique muscle

For the abdominal muscle see: Abdominal external oblique muscleThe superior oblique muscle, or obliquus oculi superior, is a fusiform muscle originating in the upper, medial side of the orbit which abducts, depresses and internally rotates the eye...

 muscle of the eye. The superior oblique muscle is innervated by cranial nerve IV (trochlear nerve

Trochlear nerve

The trochlear nerve is a motor nerve that innervates a single muscle: the superior oblique muscle of the eye....

).

Pathophysiology

Incyclotorsion may also be used to describe one part of the condition of the eye when a patient has a cranial nerve III (oculomotor nerve

Oculomotor nerve

The oculomotor nerve is the 3rd of 12 paired cranial nerves. It enters the orbit via the superior orbital fissure and controls most of the eye's movements, including constriction of the pupil and maintaining an open eyelid by innervating the Levator palpebrae superiors muscle. The optic nerve is...

) palsy

Palsy

In medicine, palsy is the paralysis of a body part, often accompanied by loss of sensation and by uncontrolled body movements, such as shaking. Medical conditions involving palsy include cerebral palsy , brachial palsy , and Bell's palsy ....

. The oculomotor nerve supplies the inferior oblique muscle (along with four other eye muscles - superior rectus, medial rectus, inferior rectus and the striated muscle of levator palpebrae superioris), and when this muscle is non-functional (as in oculomotor palsy) the eye incyclotorts; i.e. twists/rotates inward.