Anatomy LECTURE senses

what is the wall of the eye made up of

fibrous tunic

vascular tunic

neural tunic/retina

protection and shape

sclera and cornea is located here

fibrous tunic

outer white portion, tough connective tissue giving the eye its shape

sclera

transparent convex shape, light enters and is bended

cornea

blood supply and controls vision

choroid, ciliary body, and iris is located here

vascular tunic

network of capillaries, provides nutrients to the retina

choroid

controls lens structure

ciliary body

colored portion, controls pupil size

iris

composed of ciliary muscle and suspensory ligaments

ciliary body

relaxation and contraction of the ciliary muscles alter the tension of suspensory ligaments thereby……

changing the shape of the lens

ciliary muscles are relaxed and move posteriorly, pulling the suspensory ligaments taut and flattening the lens.

far vision

Ciliary muscles are contracted (move forward), the suspensory ligaments are loose and the lens is spherical

near vision

protection/fibrous build up on lens

cloudy vision

cataracts

An increase in the amount of aqueous humor in the anterior and posterior chambers.

glaucoma

what is the iris made up of

made up of 2 muscles (sphincter and dilator pupillae)

• relay visual information to the brain

• neuronal layer contains photoreceptors that receive and converts visible light to nerve impulses that are transmitted to the brain

retina

fire in dim light

rods

fore in high intensity light and in color vision

cones

lacks photoreceptors (blind spot)

optic discs

lateral to the optic disc, is a rounded, yellowish region of the retina

• the area of sharpest vision due to highest proportion of cones and almost no rods

fovea centralis

what is the general structure of the outer ear

The external ear is located mostly on the outside of the body, and the middle and inner areas are housed within the petrous portion of the temporal bone.

what is the general function of the ear

movement of the inner ear fluid result in the sensations of hearing and equilibrium or balance

in the middle ear, what does the tympanic cavity do

maintains and open connection with the atmosphere through the auditory tube

•Opens through slit-like opening into the nasopharynx (upper throat) from the middle ear

•Air movement through this tube (as a result of chewing, yawning, and swallowing) allows the pressure to equalize on both sides of the tympanic membrane

tympanic cavity

what does the tympanic cavity of the middle ear house

the auditory ossicles (malleus, incus, and stapes)

amplify acoustics, help move the joints formed by the auditory ossicles when they become stiff from old age

hearing aid

Balance, detect rotation movement of the head

semicircular ducts

Hearing, convert sound waves into nerve impulse

cochlear ducts

what do the semicircular ducts and cochlear ducts have in common

both are fluid filled and contain receptors for hearing or equilibrium

position that indicates rotation

• tilting of the head displaces the fluid and bends the sterocilia

sterocilia or hair cells

what is the cochlear duct hearing impulses

1.Sound waves enter the external auditory canal

2.The sound waves cause the tympanic membrane to vibrate

3.Tympanic membrane vibrations cause the auditory ossicles to vibrate (amplifying the sound waves)

4.Pressure waves (fluid movement) are initiated in the cochlear duct to vibrate

5.Stimulation of the CN VIII occurs leading to the primary auditory cortex of the brain

conditions interfere with transmission of vibrations to inner ear

conductive deafness

what is damaged when you are deaf

tympanic membrane, otitis media, blockage of auditory canal and otosclerosis

fusion of auditory ossicles that prevents their free vibration

otosclerosis

death of hair cells ot any nervous system elements concerned with hearing

sensorineural (nerve) deafness

who can you get sensoruneural deafness

factory workers, musicians, constructions workers