anterior segment Flashcards
1
Q
what are the three parts of the uvea
A
- iris
- ciliary body
- choroid
2
Q
what is the uvea
A
- middle tunic
- vacular, pigmented
- derived from neuroectoderm, mesoderm
3
Q
what is the iris
A
- delicate vascular network
- connective tissue, muscle, nerves
- iris curvature mimics lens
4
Q
what are the 4 structures of the iris
A
- pupillary zone
- iris collarette
- ciliary zone
- corpora nigra
5
Q
iris muscle
A
- smooth muscle in dogs and cats
- controls pupil size, amount of light entering
6
Q
sphincter iris muscle
A
- constricts pupil
- circular arrangement
- parasympathetic, CN III
7
Q
dilator iris muscle
A
- dilates pupil
- radial arrangement
- sympathetic, CN V
8
Q
ciliary body
A
- smooth muscle
- bi-layered epithelium
- lens zonular attachment
9
Q
what is the function of the ciliary body
A
aqueous humor production!
- ultra-filtrate of plasma
- fills anterior and posterior chamber
- nutrition
aqueous humor drainage (angle)
10
Q
what does ciliary muscle contraction do
A
- releases tension on lense
- fills anterior and posterior chamber
- lens becomes “fatter”
11
Q
uvea immune mechanism
A
it is immune-competent - behaves as accessory lymph node
12
Q
what is the lens
A
- transparent structure
- focuses light rays on retina
- sits between iris and vitreous
13
Q
what does the lens compromise and what is it divided into
A
- comprises capsule, anterior epithelium, lens fibers
- divided into cortex and nucleus
14
Q
what is the lens surrounded by? epithelium structure?
A
- surrounded by elastic acellular capsule
- single layer of epithelial cells on inner surface of anterior capsule
- at equator, lens epithelial cells elongate into lens fibers, loose their nucleus and organelles
15
Q
what are lens fibers
A
- upright and inverted Y “sutures” can be seen in normal lens
- new layers of lens fibers formed at equator throughout life
- older fibers pushed toward center
