Lesson 2 Final Flashcards
Special senses include:
*Smell
* Taste
* Sight
*Hearing
* Equilibrium
How many percent of all sensory receptors are in the eyes
70 percent
Anatomy of the eye
Accessory structures include the:
*Extrinsic eye muscles
* Eyelids
* Conjunctiva
* Lacrimal apparatus
Meet at the medial and lateral commissure (canthus)
Eyelids
Tarsal glands produce an oily secretion that lubricates the eye
Eyelashes
Membrane that lines the eyelids and eyeball
Conjunctiva
Connects with the transparent cornea
Conjunctiva
Lacrimal gland+ ducts
Lacrimal Apparatus
Produce lacrimal fluid (tears); situated in lateral end of each eye
Lacrimal gland
Tears drain across the eye into the lacrimal canaliculi, then the lacrimal sac, and into the nasolacrimal duct, which empties into the nasal cavity
Lacrimal Apparatus
Tears contain:
*Dilute salt
* Mucus
* Antibodies
* Lysozyme (enzyme that destroys bacteria)
Function of tears:
- Cleanse
- Protect
- Moisten
- Lubricate the eye
Six muscle attach to the outer surface of the eye
Extrinsic eye muscles
Produce gross eye movements
Extrinsic eye muscles
Three layers, or tunics, form the wall of the eyeball
- fibrous layer
- Vascular layer
- Sensory layer
Outside layer
Fibrous layer
Middle layer
Vascular layer
Inside layer
Sensory layer
Two types of fibrous layer
*Sclera
* Cornea
Two types of fibrous layer
*Sclera
* Cornea
White connective tissue
Sclera
Seen anteriorly as the “white of the eye”
Sclera
Transparent, central anterior portion
Cornea
Allows for light to pass through
Cornea
Choroid is a blood- rich nutritive layer that contains a pigment (prevents light from scattering)
Vascular layer
Regulates the amount of light entering eye
Iris
Rounded opening in the iris
Pupil
Signals leave the retina toward the brain through the optic nerve
Sensory layer
Retina contains two layers:
- Outer pigmented layer
- Inner neural layer
Where the optic nerve leaves the eyeball
Optic disc (blind spot)
Most are found toward the edges of the retina
Rods
Allow vision in dim light and peripheral vision
Rods
Allow for detailed color vision
Cones
Densest in the center of the retina
Cones
Lateral to blind spot
Fovea centralis