A&P Chapter 15 Flashcards
Accessory structures of the eye do what?
Protects the eye and aids in eye function?
What are the accessory structures of the eye?
Eyebrows, eyelids, eyelashes, conjunctiva, lacrimal gland, and 6 extrinsic eye muscles
What is the lacrimal gland?
Accessory structure that makes tears to lubricate the eyes
Where is the lacrimal gland located?
Lateral upper eye
How are tears produced?
- The lacrimal gland produces and secretes tears (lacrimal secretions)
- Tears enter the conjunctival sac via the excretory ducts of the lacrimal gland
- Tears flow down and across the eyeball
- Tears enter the lacrimal canaliculi at openings called lacrimal puncta
- Tears drain into the lacrimal sac
- From the lacrimal sac, tears empty via the nasolacrimal duct into the inferior meatus of the nasal cavity
What is the conjunctiva?
Transparent lining of eye and lid surfaces
What is the conjunctiva made of?
Specialized stratified columnar epithelium. Contains numerous goblet cells to moisten eye, many blood vessels to nourish sclera, abundant nerve endings
Does the conjunctiva cover the cornea?
No, so it doesn’t interfere with light passage
What is conjunctivitis?
Pink eye. Inflammation of the conjunctiva resulting in reddened irritated eyes. Caused by bacteria or viruses. Highly contagious
What does the lateral rectus do, and which cranial nerve controls it?
Moves eye laterally and the VI (abducens) nerve
What does the medial rectus do and which cranial nerve controls it?
Moves eye medially and the III (oculomotor) nerve
What does the superior rectus do and which cranial nerve controls it?
Elevates the eye and turns it medially and the III (oculomotor) nerve
What does the inferior rectus do and which cranial nerve controls it?
Depresses eye and turns it medially and the III (oculomotor) nerves
What does the inferior oblique do and which cranial nerve controls it?
Elevates the eye and turns it laterally and III (oculomotor) nerves
What does the superior oblique do and which cranial nerve controls it?
Depresses the eye and turns it laterally and IV (trochlear) nerve
How can you remember the eye muscles and associated cranial nerves?
LR 6 SO 4 all else 3
The interior structures of the eye contains two cavities, what are they?
- Posterior cavity (behind lens)
- Anterior cavity (in front of lens)
Where is permanent vitreous humor located?
Posterior cavity (behind lens)
Where is the circulating aqueous humor located?
Anterior cavity (in front of lens)
What is glaucoma?
Condition in which drainage of aqueous humor is blocked, causing fluid to back up and increase pressure within the eye
What is the physiology of glaucoma?
Pressures may increase to dangerous levels and compress the retina and optic nerve, leading to blindness
What are the symptoms of glaucoma?
Few early signs, but late signs include seeing halos around lights and blurred vision
What is the detection of glaucoma?
Intraocular pressure determined by directing putt of air at cornea and measuring amount of corneal deformation. Test should be done yearly after age 40
What is the treatment of glaucoma?
Eye drops that increase rate of aqueous humor drainage or decrease its production; laser therapy or surgery
What is the cornea?
The clear connective tissue layer in the front of the eyeball that bulges
What is the lens?
Flexible disc that bends light to focus it on the retina
What is the ciliary body?
The muscles that change the shape of the lens
What are the characteristics of the lens?
Biconvex, transparent, flexible, and avascular
How does the lens change shape?
Via suspensory ligaments and ciliary muscle to precisely focus light on the retina
What are cataracts?
Clouding of the lens
What causes cataracts?
Can be congenital, consequences of aging, diabetes mellitus, heavy smoking, frequent exposure to intense sunlight
What is the treatment for cataracts?
Lens can be replaced surgically with an artificial lens
What is the sclera?
The white connective tissue layer on the outside of most of the eyeball
What is the choroid?
Internal blood supply of eyeball
What is the retina?
Innermost eyeball layer that detects light
What does the pigmented layer of the retina do?
Absorbs light and prevents its scattering, phagocytizes photoreceptor cell fragments, and stores vitamin A