Which muscle of the ciliary body contracts to allow accommodation (near focus) in the eye?
- A Dilator pupillae
- B Sphincter pupillae
- C Ciliary muscle ✓
- D Superior oblique
Correct answer: C. Ciliary muscle
Explanation
The ciliary muscle (smooth muscle innervated by parasympathetic fibers via the ciliary ganglion from CN III) contracts during accommodation for near vision. Contraction of the circular fibers of the ciliary muscle moves the ciliary body forward and inward, releasing tension on the zonular fibers (of Zinn), allowing the elastic lens to become more convex and increase its refractive power. Paralysis of the ciliary muscle (cycloplegia) prevents accommodation.
Reference: BD Chaurasia's Human Anatomy, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.