Anatomy Of The Human Eye

Front 1

Layers of the Eye

Back 1

Fibrous, Vascular & Inner

Front 2

Composition of the Fibrous Layer

Back 2

Sclera & Cornea

Front 3

Composition of the Vascular Layer

Back 3

Choroid, Ciliary Body & Iris

Front 4

Composition of the Inner Layer

Back 4

(Retina) Pigmented & Neutral Layers

Front 5

Sclera

Back 5

Posterior portion of fibrous layer (white). Hard protection which shapes the eye and forms a sturdy anchoring site for extrinsic eye muscles. Posteriorly pierced by the optic nerve.

Front 6

Cornea

Back 6

Anterior sixth of fibrous layer which bulges anteriorly from its junction with the sclera. A window which lets light enter the eye. Both faces of cornea covered by epithelial sheets. Well supplied with nerve endings (mostly pain receptors). No blood vessels.

Front 7

Choroid

Back 7

Blood vessel-rich, dark brown membrane that forms the posterior five-sixths of the vascular layer. Its blood vessels nourish all eye layers. Brown pigment helps absorb light to prevent light scattering and reflecting. Incomplete posteriorly where optic nerve leaves the eye.

Front 8

Composition of the Ciliary Body

Back 8

Ciliary Muscles, Ciliary Processes & Cilary Zonule. Anteriorly in the vascular layer, the cilary body is a thickened ring of tissue that encircles the lens.

Front 9

Cilary Muscles

Back 9

Interlacing smooth muscle bundles to control lens shape (in cilary body of vascular layer).

Front 10

Cilary Processes

Back 10

Posterior surface of cilary muscles thrown into radiating folds. Secrete fluid that fills the cavity of the anterior segment of the eyeball (in cilary body of vascular layer).

Front 11

Cilary Zonule

Back 11

Suspensory ligament. Extends from cilary processes to the lens to help hold it in upright position (in cilary body of vascular layer).

Front 12

Iris

Back 12

Anterior portion of vascular layer (coloured part of eye). Lies between cornea and the lens, continuous with the cilary body posteriorly. The round central opening is the pupil which allows light to enter the eye. Muscle fibers allow it to act as a felexively activated diaphragm to vary pupil size.

Front 13

Muscles of the Iris

Back 13

Sphincter Pupillae (Circular Muscles) & Dilator Pupillae (Radial Muscles)

Front 14

Sphincter Pupillae

Back 14

Circular muscles of the iris in the vascular layer (anteriorly). In close vision and bright light they contract to make the pupil constrict. Controlled by Parasympathetic fibers.

Front 15

Dilator Pupillae

Back 15

Radial muscles of the iris in the vascular layer (anteriorly). In distant vision and dim light they contract and the pupil dialates to allow more light in. Controlled by Sympathetic fibers.

Front 16

Pigmented Layer of the Retina

Back 16

The outer layer of the retina which is a single-cell-thick-lining which abuts the choroid, and extends anteriorly to cover the ciliary body and the posterior face of the iris. The pigment cells absorb light and prevent it from scattering in the eye. Participates in photoreceptor cell renewal (vitamin A stores).

Front 17

Neutral Layer of the Retina

Back 17

Transparent inner layer which extends anteriorly to the posterior margin of the cilary body (ora serrata). Neutron composition from posterior to anterior: Photoreceptors, Bipolar Cells, Ganglion Cells. Optic disk, where the optic nerve exits the eye, is a weak spot in the fundus (posterior wall) as it is not reinforced by the sclera - is called the blind spot because it lacks photoreceptors.

Front 18

Composition of Neutrons in Neutral Layer of Retina (posterior to anterior)

Back 18

Photoreceptors, Bipolar Cells, Ganglion Cells.

Front 19

Two Types of Photoreceptors in Neutral Layer of Retina

Back 19

Rods & Cones

Front 20

Rods

Back 20

Dim-light and peripheral vision receptors, but do not provide sharp images or colour vision (photoreceptors in Neutral Layer of the Retina).

Front 21

Cones

Back 21

Vision receptors for bright light and provide high resolution colour vision (photoreceptors in Neutral Layer of the Retina).