BIOL 1410 Lecture Notes - Lecture 20: Fovea Centralis, Ciliary Muscle, Optic Disc
1 May 2018
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TOPIC XX: SPECIAL SENSES
A) Special Senses: Eye
3 layered sphere filled with fluid
structural features:
1) Fibrous Tunic: avascular
parts:
a) sclera (white)
avascular connective tissue (CT)
b) cornea (transparent)
avascular CT
c) conjunctiva
covers anterior sclera
vascular mucous membrane
o when vessels dilate = bloodshot eyes
2) Vascular Tunic
parts:
a) choroid (posterior)
contains melanin
highly vascular
b) ciliary body (anterior)
ciliary muscle + ciliary processes – focus the lens
c) iris
coloured part of eye
d) pupil
hole in iris
3) Nervous (Sensory) Tunic = Retina:
parts:
a) outer pigmented layer
b) inner neural layer
3 layers of neurons:
i. Photoreceptors (2 types)
Rods – black + white
Cones - colour
ii. Bipolar Cells
iii. Ganglion Cells
axons from optic nerve (= Cranial Nerve II)
c) fovea centralis
where light is focused
= area of greatest visual acuity
no rods, just cones
d) optic disc
blind spot where blood vessels + optic nerve exit eye
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Document Summary
Topic xx: special senses: special senses: eye. Avascular connective tissue (ct: cornea (transparent) Vascular mucous membrane: when vessels dilate = bloodshot eyes, vascular tunic. Ciliary muscle + ciliary processes focus the lens: iris. Hole in iris: nervous (sensory) tunic = retina: Parts: outer pigmented layer, inner neural layer. 3 layers of neurons: photoreceptors (2 types) Cones - colour: bipolar cells, ganglion cells. Axons from optic nerve (= cranial nerve ii: fovea centralis. No rods, just cones: optic disc. Blind spot where blood vessels + optic nerve exit eye. Cataracts = clouding of lens: anterior segment. Contains aqueous humor fluid similar to plasma: posterior segment. Contains vitreous humor: gel-like, special senses: ear. Elastic cartilage, covered with skin: external auditory canal (meatus, tympanic membrane (eardrum, middle ear. Also called pharyngotympanic tube: ear ossicles, malleus. Secured to tympanic membrane: incus, stapes transmits sound to inner ear via oval window, inner ear (labyrinth) Parts: bony labyrinth tunnels in temporal bone, contain perilymph.
