Chapter 2 Flashcards
Describe how the eye converts light rays to a perceived image, naming the principal structures involved in the process.
Light Rays are reflected from an object are focused by the cornea and the lens to produce an upside down image of the object on the light sensitive retina. The retina converts the image to electric impulses, which are carried by the optic nerve to the brains visual cortex, where they produce the sensation of sight.
Name 4 primary structures included in the adnexa.
Orbit, extraocular muscles, eyelids, lacrimal apparatus.
Describe the structure and function of the orbit.
The bony cavity in the skull that houses the globe, extraocular muscles, blood vessels and nerves ; protects the globe from major injury by a rim of bone.
Match the 6 extraocular muscles with their functions
- Medial Rectus. A. Outward rotation
- Lateral Rectus. B. Upward rotation
- Superior Rectus. C. Downward rotation
- Inferior Rectus. D. Inward rotation
- Superior Oblique. E. Excyclotorsion, up and outward
- Inferior Oblique. F. Incyclotorsion, down and inward
- D
- A
- B
- C
- F
- E
What are the 3 functions of the of the eyelids?
To protect the eye from injury, to exclude light, and to aid in lubricating the ocular surface.
Name the three layers of the eyelid.
Outer layer of skin, middle layer of fibrous tissue and muscle, inner layer of tissue (conjunctiva).
What are the 2 principal functions of the Lacrimal Appartatus?
To produce and drain tears.
Give four reasons why tears are important to the functioning of the eye.
Ocular comfort, clear vision, provide moisture and nourish the eye
What is the relationship between the lacrimal gland, lacrimal sac and nasolacrimal duct?
Tears are produced by the lacrimal gland; tears are collected in the lacrimal sac; tears drain into the nasal cavity by means of the nasolacrimal duct.
Name the 3 layers of tear film and their functions.
The outer, oily layer helps prevent evaporation of moisture from the middle, aqueous layer; the middle layer provides moisture, oxygen, and nutrients to the cornea; the inner mucinous layer promotes even spread of the tear film.
What is the principal function of the cornea?
To focus light ray’s reflected to the eye, contributing about two-thirds of the focusing power of the eye.
Match the 5 layers of the corneal tissue with their functions. (Two of the layers preform the same function.)
- Endothelium A. Serves as first line of defense against infection and injury
- Epithelium B. Contributes rigidity
- Bowman membrane C. Acts as an anchor for epithelium
- Descemet membrane D. Maintains proper fluid balance
- Strom
- D
- A
- C
- B
- B
What is the main function of the Sclera?
To protect intraocular contents.
Why is a balance between the inflow and outflow of aqueous humor important?
To maintain intraocular pressure.
Describe the course of aqueous humor into and out of the eye, naming the principal ocular structures involved.
Aqueous humor enters the eye from behind the iris, flows across the back of the iris, through the pupil, and into the anterior chamber; it leaves the anterior chamber at the filtration angle and passes through the trabecular meshwork, the canal of Schlemm, aqueous veins and into the blood vessels.
