A sphincter muscle that is part of the iris. [ http://en.wikipedia.org/wiki/Iris_sphincter_muscle ]
Synonyms: iris sphincter muscle musculus sphincter pupillae M. sphincter pupillae sphincter muscle of pupil
Term information
- BTO:0000656
- Wikipedia:Iris_sphincter_muscle
- UMLS:C0229189 (ncithesaurus:Sphincter_Pupillae_Muscle)
- SCTID:280889004
- FMA:49157
- EMAPA:35788
- MA:0001289
- NCIT:C33586
uberon_slim
pupillary constrictor muscle
sphincter pupillae
pupillary sphincter
constrictor pupillae
sphincter pupillae muscle
m. sphincter pupillae
circular fibers
pupillary sphincter muscle
spincter pupillae
iris constrictor
iris sphincter
iris constrictor muscle
WP says: It is found in vertebrates and some cephalopods; this class refers to the vertebrate structure
In humans, it functions to constrict the pupil in bright light or during accommodation. Its dimensions are about 0.75 mm wide by 0.15 mm thick. It is controlled by parasympathetic fibers that originate from the Edinger-Westphal nucleus, travel along the oculomotor nerve (CN III), synapse in the ciliary ganglion, and then enter the eye via the short ciliary nerves. Initially, all the myocytes are of the smooth muscle type, but much later in life, so that ultimately most cells are of the striated muscle type. [WP,unvetted]
Term relations
- iris smooth muscle
- sphincter muscle
- smooth muscle sphincter
- muscle of iris
- part of some iris
- develops from some neurectoderm
- part of some system
- has muscle antagonist some dilatator pupillae
- has muscle insertion some iris
- has muscle origin some iris