The circular muscle of the iris
A) contracts in response to bright light to produce pupillary constriction.
B) is innervated by the parasympathetic nervous system.
C) contracts to slacken the suspensory ligaments and increase the strength of the lens during accommodation.
D) both (a) and (b) above.
E) all of these answers.

Question

Quizplus · Accepted Answer

The circular muscle of the iris contracts in response to bright light to produce pupillary constriction, which is controlled by the parasympathetic nervous system. Therefore, both choices (a) and (b) are correct. However, choice (c) is incorrect as this describes the function of the ciliary muscle, not the circular muscle of the iris.

The Circular Muscle of the Iris