The levator-trochlear muscle. A supernumerary orbital structure.

A supernumerary extraocular muscle was present in seven of 98 cadaver orbits. The muscle originates from the medial border of the levator palpebrae superioris and has a diaphanous insertion on the fascia in the region of the trochlea and other nearby structures. Innervation is from a branch of the superior division of the oculomotor nerve. The muscle has been called the tensor trochleae in the past, but since its action is not apparent, it is more appropriately named the levator-trochlear muscle. It could be the cause of otherwise poorly understood forms of ocular deviations.