MedBucket

The ciliar body is a part of the middle layer of the eye. It is located between iris and ora serrata. Its external side is pretty smooth, and it leans onto sclera, especially on the front side. The internal side is pretty creased, and divided into two zones — orbiculus ciliars, which is closer to the equator and has smaller creases (plicae orbiculares) and corona ciliaris, which is more to the front and has bigger creases (processus ciliares majores). Between these ciliary creases there are ciliary notches called sulci ciliares. In them, there are fibers called zonula ciliaris, which hold the lens in its position.

The ciliar body is built similarly to choroid — it contains two parts. The first one (pars vascularis) is a lot of binder tissue full of blood vessels and pigment cells, while the second one (to the outside) is the ciliary muscle (musculus ciliaris).

The ciliary muscle is comprised of three parts:

1. Fibrae meridionales
2. Fibrae radiales
3. Fibrae circulares

When the ciliary muscle gets contracted, it pulls the choroid to the front, thus making the zonula ciliaris to loosen the lens. The lens bulges and the eye becomes accommodated for nearness. Contrary to that, when the ciliary muscle gets relaxed, it pulls the choroid to the back, thus making the zonula ciliras to tighten the lens. The lens excavates and the eye becomes accommodated for distance.

The innervation comes from the ciliary nerves  through the ganglion ciliare, which form the plexus gangliosus ciliaris around the muscle.