Müller's muscle

The term Müller's muscle is sometimes used as a synonym.

Given the possible confusion, the use of the term Müller's muscle should be discouraged unless the context removes any ambiguity.

"Müller's muscle": Circular portion of the ciliary muscle of the eye.

Not to be confused with the Superior tarsal muscle or the circular fibres of the ciliary muscle, both of which are also known as Müller's muscle.

The Müller's muscle, or the superior tarsal muscle, in the upper eyelid and the inferior palpebral muscle in the lower 2 eyelid are responsible for widening the eyes.

While the orbitalis muscle is also known as Müller's muscle, the use of this term should be discouraged to avoid confusion with the superior tarsal muscle and the circular fibres of the ciliary muscle.