What are the three tunics of the eyeball?

What are the three tunics of the eyeball?

The wall of the eye is composed of three layers: the fibrous tunic, vascular tunic, and neural tunic.

What makes up the vascular tunic?

The vascular tunic is comprised of three distinct regions, (1) the iris, (2) the ciliary body, and (3) the choroid. The vascular tunic is mesodermal in origin and is situated between the outer fibrous tunic and the inner nervous tunic. The vascular tunic is also refered to as the uvea.

What is the fibrous tunic?

The fibrous tunic is composed of the sclera and the cornea. The sclera covers nearly the entire surface of the eyeball. With its external surface being white-coloured, it is commonly known as the “white of the eye”. The transparent cornea occupies the front center part of the external tunic.

What tunic does the cornea belong to?

The sclera and cornea form the fibrous tunic of the bulb of the eye; the sclera is opaque, and constitutes the posterior five-sixths of the tunic; the cornea is transparent, and forms the anterior sixth.

What are tunics anatomy?

In modern biology in general, tunica occurs as a technical or anatomical term mainly in botany and zoology. It usually refers to membranous structures that line or cover particular organs. An organ or organism that has a tunic(a) may be said to be tunicate, as in a tunicate bulb.

What is the major function of aqueous Humour?

The major functions of aqueous humor include maintaining intraocular pressure, providing nutrients to the cornea and lens (which are avascular), and removing wastes from the cornea and lens.

Where is aqueous humor drained?

Aqueous humour drains out of the eye through the trabecular meshwork. The trabecular meshwork is a spongy mass of tiny canals located in the drainage angle. The drainage angle is located between the iris and the clear covering of the eye (cornea), where the iris meets the white outer covering (sclera) of the eye.

What are tunics of the eye?

The eye is made up of three layers: the outer layer called the fibrous tunic, which consists of the sclera and the cornea; the middle layer responsible for nourishment, called the vascular tunic, which consists of the iris, the choroid, and the ciliary body; and the inner layer of photoreceptors and neurons called the …

What is a tunic in zoology?

In biology, a tunica (/ˈtuːnɪkə/; UK: /ˈtʃuːn. ɪ. kə/) (plural tunicae) is a layer, coat, sheath, or similar covering. The word came to English from the New Latin of science and medicine. An organ or organism that has a tunic(a) may be said to be tunicate, as in a tunicate bulb.

What is another word for tunic?

synonyms for tunic

• blouse.
• coat.
• jacket.
• robe.
• chiton.
• kirtle.
• surcoat.
• toga.

FIG. 869– Horizontal section of the eyeball. From without inward the three tunics are: (1) A fibrous tunic, (Fig. 869) consisting of the sclera behind and the cornea in front; (2) a vascular pigmented tunic, comprising, from behind forward, the choroid, ciliary body, and iris; and (3) a nervous tunic, the retina.

How is the vascular tunic of the eye formed?

—The vascular tunic of the eye is formed from behind forward by the choroid, the ciliary body, and the iris. The choroid invests the posterior five-sixths of the bulb, and extends as far forward as the ora serrata of the retina. The ciliary body connects the choroid to the circumference of the iris.

What is the projecting transparent part of the external tunic?

The Cornea.—The cornea is the projecting transparent part of the external tunic, and forms the anterior sixth of the surface of the bulb. It is almost circular in outline, occasionally a little broader in the transverse than in the vertical direction.

What is the shape of the cornea?

The cornea is dense and of uniform thickness throughout; its posterior surface is perfectly circular in outline, and exceeds the anterior surface slightly in diameter.