Superior transverse ligament of eyeball

The superior transverse ligament of eyeball (a.k.a. the Whitnalls ligament) is a fibrous condensation of orbital fascia, located in the superior part of the orbit. It spans side to side, extending medially from the region of the trochlea to the lateral orbital wall near the lacrimal gland, and is closely associated with the levator palpebrae superioris (LPS) muscle.

Relationship with the levator palpebrae superioris muscle

Functionally, the superior transverse ligament serves as the transition point or fulcrum between the posterior muscular part of the levator palpebrae superioris and its anterior aponeurotic extension, the levator aponeurosis. The levator palpebrae superioris muscle originates from the lesser wing of the sphenoid bone near the orbital apex and courses anteriorly within the orbit. At the level of superior transverse ligament of eyeball, the muscle is suspended and changes direction, allowing its line of pull to shift from an anteroposterior direction to a more supero-inferior direction. In this way, the superior transverse ligament is thought to function as a mechanical pulley or lever for the levator muscle.

Anterior to the superior transverse ligament, the levator muscle becomes thinner and expands inferiorly as the levator aponeurosis. This aponeurotic portion spreads medially and laterally to form the medial and lateral horns, which attach to their respective canthi. Inferiorly, the aponeurosis inserts into the lower one-third of the superior tarsal plate of the upper eyelid. The muscular portion of the levator is approximately 40 mm long, whereas the aponeurotic portion measures approximately 1420 mm.

Other functions

In addition to its role of superior transverse ligament as a fulcrum for the levator palpebrae superioris muscle, the ligament also contributes to suspension and support of the upper eyelid. Clinically, it is an important landmark in ptosis and eyelid surgery because of its close relationship to the levator aponeurosis and upper eyelid support mechanisms.