Pupillary Sphincter (Noun)
Meaning
A ring of smooth muscle surrounding the iris.
Classification
Nouns denoting body parts.
Examples
- The iris contains two types of smooth muscle, including the pupillary sphincter, which controls the diameter of the pupil.
- Damage to the pupillary sphincter can result in an irregularly shaped pupil or a pupil that is unresponsive to light.
- The pupillary sphincter is innervated by the oculomotor nerve and contracts to constrict the pupil in bright light.
- Abnormalities in the pupillary sphincter can be a sign of neurological disorders such as Horner's syndrome or third nerve palsy.
- The pupillary sphincter works in conjunction with the dilator pupillae muscle to regulate the amount of light that enters the eye.