superior tarsal muscle

The superior tarsal muscle (Müller muscle or cremaster tarsus) is a small muscle of the superior orbit arising from the undersurface of the levator palpebrae superioris muscle that elevates and retracts the upper eyelid. It is not part of the extraocular muscles; it does not insert on the globe and therefore does not produce eye movements. It is composed of smooth muscle fibers which are under sympathetic control.

Summary

• origin: undersurface of the levator palpebrae superioris muscle
• insertion: upper margin of the superior tarsal plate
• innervation: sympathetics on the superior branch of the oculomotor nerve (CN III) derived from the internal carotid artery sympathetic plexus
• action: elevates and retracts the upper eyelid

Clinical significance

• Horner syndrome, due to injury or pathology of the cervical sympathetic chain, can lead to reduced sympathetic innervation of the muscle and cause ptosis. There are usually other signs of Horner syndrome present to help differentiate from other causes of ptosis.

Siehe auch:

• Lidgerüst
• Musculus tarsalis inferior
• Musculus levator palpebrae superioris