Iris sphincter muscle

The iris sphincter muscle (pupillary sphincter, pupillary constrictor, circular muscle of iris, circular fibers) is a muscle in the part of the eye called the iris. It encircles the pupil of the iris, appropriate to its function as a constrictor of the pupil.

Iris sphincter muscle
Iris, front view. (Muscle visible but not labeled.)
The upper half of a sagittal section through the front of the eyeball. ("Sphincter of pupil" labeled near bottom-center.)
Details
Originencircles iris
Insertionencircles iris
Arterylong posterior ciliary arteries
Nerveshort ciliary nerves
Actionsconstricts pupil
Antagonistiris dilator muscle
Identifiers
Latinmusculus sphincter pupillae
TA98A15.2.03.029
TA26762
FMA49157
Anatomical terms of muscle
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