Ciliary Body Anatomy Lecture Review

Vocabulary flashcards covering the anatomy, dimensions, histological layers, blood supply, innervation, and functions of the ciliary body based on Dr. Chronister's lecture notes.

Ciliary Body

Anterior continuation of the choroid that is triangular in shape, longer temporally, darker than the choroid, highly vascular, and consists of a ring of smooth muscle tissue.

Dimensions of Ciliary Body

Always longest inferotemporally (the most expanded quadrant of the eye), measuring $7\,\text{mm}$ temporally and $6\,\text{mm}$ nasally.

Pars Plicata

Anterior $\frac{1}{3}$ of the ciliary body closest to the lens that produces aqueous humor and contains inner surface folds called ciliary processes.

Pars Plana

Posterior $\frac{2}{3}$ of the ciliary body that is $3.5\text{ to }4\,\text{mm}$ wide, flat on its inner surface, adjacent to the ora serrata and retina, and produces some components of the vitreous.

Ciliary Processes

The $70\text{--}80$ folds on the inner surface of the anterior $\frac{1}{3}$ of the ciliary body (pars plicata) that provide surface area for aqueous production.

Striae Ciliaris

Strips extending from the dentate processes into the ciliary body.

Dentate Processes

The "teeth" of the retina that extend into the ciliary body.

Oral Bays

Oval extensions of the ciliary body into the retina.

Supraciliaris

Histological layer of the ciliary body containing a potential space continuous with the suprachoroidal space and fine collagen fibrils, acting as a conduit for nerves and blood vessels.

Ciliary Muscle

Smooth muscle tissue composed of longitudinal, radial, and circular fibers originating from the scleral spur that gives the ciliary body its triangular shape and functions in accommodation and aqueous outflow.

Longitudinal Muscle Fibers

Clinically most important ciliary muscle fibers that insert as muscle stars into the choroid; strong contraction can sometimes cause retinal detachment.

Ciliary Body Stroma

Thin layer of loose connective tissue located between the ciliary muscle and double epithelial layer containing nerves, blood vessels, fibroblasts, lymph, and mast cells.

Stromal Capillaries

Capillaries within the ciliary body stroma that are fenestrated on all sides to provide substances necessary for aqueous production.

Desmosomes and Zonula Adherens

Intercellular junctions between the ciliary body epithelia that prevent separation of the epithelial layers during ciliary body contraction.

Zonula Occludens

Ultrastructure tight junctions in the non-pigmented epithelium of the ciliary body that form the blood-aqueous barrier.

Pigmented Epithelium (Ciliary Body)

Layer of the ciliary body continuous anteriorly with the iris myoepithelium.

Non-Pigmented Epithelium (Ciliary Body)

Layer of the ciliary body continuous anteriorly with the posterior pigmented epithelium of the iris, from which zonules originate.

Zonules

Fibers composed mostly of fibrillin originating from the non-pigmented epithelium (mainly pars plana) that attach to the lens equator and relax tension upon ciliary muscle contraction to allow accommodation.

Major Arterial Circle

Arterial circle formed by the anastomosis of the long posterior ciliary artery and the major perforating branch of the anterior ciliary artery, giving off branches that supply the ciliary body.

Parasympathetic Innervation (Ciliary Body)

Pathway originating in the EW Nucleus III, traveling with CNIII, synapsing in the ciliary ganglion, and traveling via short ciliary nerves to activate $\text{M}_3$ muscarinic receptors and cause ciliary muscle contraction.

Sympathetic Innervation (Ciliary Body)

Pathway originating in the superior cervical ganglion, traveling with the ICA and ophthalmic nerve via short and/or long ciliary nerves to activate $\text{Beta}_2\text{-adrenergic}$ receptors and relax the ciliary muscle.

Sensory Innervation (Ciliary Body)

Pathway transmitting pain signals from the iris/ciliary body via V1 long and short ciliary nerves to the nasociliary nerve, ophthalmic nerve, and trigeminal ganglion.