q20 - kola

[ArchivalUser]

An increase in refractive power is produced by contraction of the ? 1. Iris

2. Ciliary body

3. Suspensory ligaments

4. Extraocular muscles

5. Pupil

[ArchivalUser]

3...

[ArchivalUser]

The Correct Answer is: Ciliary body
Explanation:



Contracting the ciliary body increases the refractive power of the eye for near vision. The ciliary body is a smooth muscle located at the sclerocorneal junction where the suspensory ligaments surrounding the lens are attached. The suspensory ligaments are normally taut, keeping the eye flat. When the ciliary muscle contracts, the suspensory ligaments are pulled toward the cornea. They become slack and permit the elastic lens fibers to recoil. Recoiling of the lens causes the lens surface to bulge, increasing its refractive power. The muscles of the iris control the size of the pupils, and the extraocular muscles control the position of the eye in the socket.