layers of RETINA

Question 1

a complex peripheral nervous mechanism composed of many elements

Answer 1

RETINA

Question 2

RETINA Came from the word “rete” which means

Answer 2

NETWORK (a network of neurons- visual cells, bipolar cells & ganglionic cells)

Question 3

thickness of retina

Answer 3

0.1mm - 0.5 mm

Question 4

retina is attached to the

Answer 4

underlying choroid only at the optic disc and ora serrata

Question 5

• Consists of a thin, single layer of hexagonal cells which contain minute crystals of a black pigment • Its flat cells are so closely applied to the choroid that in separating the retina from the choroid, the pigment layer is apt to adhere to the choroid • The pigment aids in absorbing light (lacking in albinos)

Answer 5

1. RETINAL PIGMENTED EPITHELIUM (RPE)

Question 6

the elements of the retina which receive the light stimulus & in which is generated the nerve impulse- “visual cells”

Answer 6

Layers of rods and cones/THE VISUAL CELLS (SENSORY EPITHELIUM)- SENSORY NEUROEPITHELIUM

Question 7

length and diameter of rods

Answer 7

0.06 mm long, 0.002 mm in diameter

Question 8

number of rods in the each eye

Answer 8

•130,000,000

Question 9

length and diameter of cones

Answer 9

0.035 mm in length, 0.006 mm in diameter

Question 10

number of cones in each eye

Answer 10

•6,000,000 in number/eye

Question 11

•Sieve-like membrane through the perforations of which rods & cones project, not a distinct membrane but a structure formed by the joining of the outer ends of the fibers of Mueller.

Answer 11

EXTERNAL LIMITING LAYER

Question 12

•Contains the cell bodies of rods and cones

Answer 12

OUTER NUCLEUS LAYER

Question 13

•Synapse of axons of visual cells & dendrites of bipolar cells & horizontal cells

Answer 13

OUTER MOLECULAR LAYER (OUTER PLEXIFORM LAYER)

Question 14

cells lying in the inner nuclear layer that make contact with cones (to convey impulses from the visual cells to the ganglionic cells)

Answer 14

BIPOLAR CELLS-

Question 15

cells that are devoid of dendrons but abundantly supplied with many much branching dendrons which lie wholly within the inner molecular layer

Answer 15

AMACRINE CELLS-

Question 16

cells in which connect the cones with each other - called association fibers by which one part of the retina may influence another

Answer 16

HORIZONTAL CELLS-

Question 17

make connections with the axons of the bipolar cells

Answer 17

GANGLIONIC CELLS-

Question 18

•Contains amacrine, bipolar, & horizontal cells, nuclei of Mueller’s fibers & capillaries of CRA

Answer 18

INNER NUCLEAR LAYER

Question 19

•Synapse of axons of bipolar cells & dendrites of ganglionic cells & amacrine cells

Answer 19

INNER MOLECULAR LAYER (INNER PLEXIFORM LAYER)

Question 20

•Contains large cell bodies whose neurons send axons into nerve fiber layer

Answer 20

GANGLIONIC CELL LAYER

Question 21

•Forms the 90 degree angle

Answer 21

NERVE FIBER LAYER

Question 22

•Between nerve fiber layer & vitreous; the inner limit of the retina; partially performed by the ends of the Mueller’s fibers

Answer 22

INTERNAL LIMITING LAYER

Question 23

• the yellow spot- lying about 3.0 mm to the temporal side of the optic disc

Answer 23

MACULA LUTEA

Question 24

diameter of macula

Answer 24

measures about 1mm - 3.0 mm in diameter

Question 25

macula is yellowish due to the yellowish pigment in the bipolar cells & ganglionic layers called?

Answer 25

xanthophylls

Question 26

-Retinal area of greatest visual acuity (in daylight vision) -in the center of macula the retina is very much thinned down (0.1 mm) giving rise to a little pit or depression displacement by the bipolar cells and ganglionic neurons towards the periphery of the macula; leaving only the visual cells layer

Answer 26

FOVEA CENTRALIS

Question 27

• are found only nerve fibers - absence of the retina renders this spot incapable of receiving impressions of light known as blind spot (Mariotte’s spot)

Answer 27

OPTIC DISC

Question 28

other term for blind spot

Answer 28

Mariotte’s spot

Question 29

A small depression in the center of the disc, where CRA enters & the CRV leaves in the eye

Answer 29

PHYSIOLOGICAL CUP

Question 30

•A dentate line about 8.5 mm back of the sclero-corneal junction

Answer 30

ORA SERRATA- (ORA-MARGIN; SERRA- A SAW)

Question 31

•3.0-3.5 mm, fibers from the ganglionic cells on reaching the surface of the retina bend at right angles & course over the retina to reach the optic disc

Answer 31

OPTIC NERVE

Question 32

nerve fibers from the ganglionic cell layer to their exit through the canal

Answer 32

Non-myelinated (medullated) nerve fibers

Question 33

nerve fibers after passage through canal but they are devoid of neurilemma.

Answer 33

Myelinated (Medullated) nerve fibers