Anatomy and Physiology

Question 1

Orbit

Answer 1

Bony structures in the skull that houses the eyeball (globe).

Question 2

7 Bones of the orbit

Answer 2

Ethmoid
Frontal
Lacrimal
Maxillary
Palatine
Sphenoid
Zygomatic

Question 3

Cranial Nerves:
III
IV
VI
VII

Answer 3

Oculomotor-opens eye, elevation, depression, adduction, extortion/elevation, accommodation (parasympathetic).
Trochlear-intortion/depression
Abducens-abduction
Facial Nerve-Closes eye

Question 4

Cranial Nerves and muscles:
III
IV
VI
VII

Answer 4

Occulomotor-Levator Palpebrae, Superior rectus, inferior rectus, medial rectus, inferior oblique, ciliary muscle
Trochlear- Superior oblique
Abducens-lateral rectus
Facila nerve-Orbicularis oculi

Question 5

OCC III parasympathetic

OCC III sympathetic

Answer 5

Iris sphincter muscle-constricts pupil

Iris Dilator Muscle-dilates pupil

Question 6

Eyeball (globe)

Answer 6

Structures that focus and transmit light to the brain for the sense of sight
average length-24 mm
average keratometry (measurement of the curvature of the anterior surface of the cornea)-42.50 d

Question 7

Cornea

Answer 7

clear, dome shaped, avascular (no blood vessels), comprised of 5 layers, provides 2/3 of the refracting power of the eye (bends light rays into retina), average central thickness (500 microns) 0.5mm

Question 8

Anterior Chamber

Answer 8

Space between corneal endothelium and iris surface

Contains aqueous humor to maintain intraocular pressure

Question 9

Iris

Answer 9

Colored portion of eye
Regulates amount of light entering globe
Contains sphincter and dilator muscles that control pupil size.

Question 10

Crystalline Lens

Answer 10

Clear, disc shape
Helps bring rays of light into focus on the retina. When the ciliary muscle in relaxed during distance vision, the crystalline lens counts for up to 1/3 of the eye’s refracting power. The process of accommodation occurs when the ciliary muscle contracts, releasing tension on the zomular fibers and allowing the crystalline lens to expand, resulting in increased plus power of the eye that allows for near vision. The process of accommodation decreases after the age of 40.

Question 11

3 parts of crystalline lens:

Answer 11

Capsule, cortex, nucleus

Question 12

Angular structure

Answer 12

Aqueous humor is produced by ciliary body.
Flow of aqueous humor
Behind the iris into posterior chamber
Through the pupil and into anterior chamber
Out through the trabecular meshwork
Into the Canal of Schlemn
Exiting eye through episcleral veins

Question 13

Vitreous body

Answer 13

Clear, gel-like substance
Occupies 2/3 of the volume of the eye
Provides for some retinal nutrition

Question 14

Retina

Answer 14

Receives light impulses and transmit them to the brain via the optic nerve.
10 layers
Two photoreceptor types
     Rods-120 M
     Cones-6M

Question 15

Layers of the retina

Answer 15

Bruch's membrane
Pigment epithelium
Rods and cones
External limiting membrane
Outer nuclear layer
Outer Plexiform layer
Inner nuclear layer
Inner plexiform layer
Ganglion cell layer
Capillary
Nerve fiber layer
Internal limiting membrane

Question 16

Choroid

Answer 16

Intraocular blood supply for the retina

Question 17

Schlera

Answer 17

protective outer layer of the eye (covered by the conjunctiva)

Question 18

Limbus

Answer 18

Junction between the corneal epithelium and conjunctiva

Question 19

Lacrimal Gland

Answer 19

responsible for tear production

Question 20

Medial rectus
Lateral rectus
Superior rectus

Answer 20

Rotates eye inward
Rotates eye outward
Turns eye upward

Question 21

Inferior rectus
Superior oblique
Inferior oblique

Answer 21

Turns eye downward
Rotates eye down and inward
Rotates eye up and outward

Question 22

Eyelids

Answer 22

Upper and lower moveable folds that acts as shutters
Protect the eye
Keep out light
Spread tear film evenly over cornea

Question 23

Puncta

Answer 23

Tiny openings on upper and lower eyelid margins near nose that drains excess tears (puncture is the singular form)

Question 24

Eyelashes (cilia)

Answer 24

Sweep away airborne dust particles and other foreign matter when eyelids blink

Question 25

Levator Palpebrae superioris muscle

Answer 25

Elevates eyelid

Question 26

Orbicularis oculi muscle

Answer 26

Circular muscle that closes eyelid

Question 27

Conjunctiva

Answer 27

Translucent membrane from limbus to inner portion of the lid margin

Question 28

Three areas of the conjunctiva:

Answer 28

Bulbar-covers eyeball
Palpebral-lines inner surface of upper and lower eyelid
Fornix-where bulbar and palpebral conjunctiva meet

Question 29

Tear film: Three layers

Answer 29

Outer: lipid (oily)- secreted by meibomian gland (prevents evaporation of tears)
Middle: aqueous-secreted by lacrimal gland (supplies cornea with moisture, nutrients and oxygen)
Inner: Mucous-secreted by goblet cells (promotes even spread of tear film over cornea)

Question 30

Tear production

Answer 30

Main volume of tear production arises from the lacrimal gland

Question 31

Tear outflow

Answer 31

Punctum—>Canaliculi—>Lacrimal Sac—>Nasolacrimal Duct

Question 32

Tears leave the eye in the following manner:

Answer 32

The tear film is spread over the ocular surface by the closure of the lids with each blink.
The blink mechanism (tear pump) directs the tears toward the puncture; into the canaliculi; to the lacrimal sac; and then the nasolacrimal duct

Question 33

Uveal tract

Answer 33

Composed of iris choroid and ciliary body
Pigment layers of the eye
Contains most of the intraocular blood vessels

Question 34

Rods

Answer 34

120 millions rods (ration 20:1-rods:cones)
Concentrated in peripheral retina
Function best in dim light
Allows detection of movement peripherally

Question 35

Cones

Answer 35

6 million cones
Concentrated in macula
Function best in lighted conditions
Allows fine resolution and detection of colors

Question 36

Optic Disc

Answer 36

Area in retina where retinal nerve fibers leave the eye (resulting in a physiological blind spot)