Ocular Anatomy 6 Ciliary Body

Question 1

Embryology of the ciliary body

Answer 1

Neuroectoderm and mesenchyme
Ciliary epithelium is formed from anteiror edge of optic cup but does not differentiate like the rest of the retina

Question 2

When does the ciliary processes form?

Answer 2

3 months gestation, epithelium thrown into folds forming ciliary processes

Fourth and sixth month differentiation occurs to produce tight junctions and interdigitations

Ciliary stroma formed from mesenchyme lying between the optic cup and the cornea with primitive muscle becoming visible at 3 months

Question 3

What is the structure of the ciliary body

Answer 3

Circular structure composed of ciliary stroma, bilatered epithelium and the ciliary muscle.

Question 4

What are the anterior and posterior relations of the ciliary body

Answer 4

Continuous with the choroid posteriorly at the pars plana and with the peripheral iris anteriorly

Question 5

What are the ciliary processes?

Answer 5

The epithelium at the pars plicata that have been thrown into folds and form attachments for the zonular fibres of the lens

Question 6

What is ciliary epithelium? How do they lie?

Answer 6

Bilayered cuboidal epithelium
Form the blood aqueous barrier

Two cell layers lie apex to apex, innner layer being rich in golgi and rough endoplasmic reticulum while outer layer contains numerous melanocytes

Question 7

What is the basement membrane of the inner layer of the ciliary epithelium continuous with? Outer layer?

Answer 7

Inner layer - internal limiting membrane
Outer layer - retinal pigment epithelium

Question 8

What type of muscle is the ciliary msucle and how are these divided?

Answer 8

Smooth muscle

Longitudinal, oblique and circular fibres

Question 9

What is the function of the longitudinal fibres of the ciliary muscles?

Answer 9

Runs posteriorly and attached to the choroidal stroma which moves anteriorly when the eye accomodates

Question 10

What is the function of the oblique fibres of the cilairy msucles?

Answer 10

Radiating from the scleral spur, increase the facilitation of aqueous outflow when contracting

Question 11

What is the function of the circular fibres?

Answer 11

Most internal, contraction slackens the tension in the zonular fibres increasing the refractive power of lens