Orbitalis muscle

Orbitalis muscle is a vestigial or rudimentary nonstriated muscle (smooth muscle) that crosses from the infraorbital groove and sphenomaxillary fissure and intimately united with the periosteum of the orbit. It was described by Johannes Peter Müller and is often called Muller's muscle.

One characteristic of Horner's Syndrome is enophthalmos (retraction of the eyeball into the orbit due to paralysis of the orbitalis muscle that spans the inferior orbital fissure).

Its function is presumed to be eyeball protrusion.

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.

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