Ear, Eye and Vestibular Anatomy Flashcards
Name the 2 cavities of the eyeball, their functions and what they are filled with
1) anterior segment, functions to maintain intra-ocular pressure, diffuses gases and nutrients, filled with aqueous humour
2) posterior segment, functions to maintain intra-ocular pressure and provides structural support, filled with vitreous humour
What causes glaucoma and what are the effects, symptoms and treatments
glaucoma is caused by increased intra-ocular pressure where there is an imbalance between production and clearance of aqueous humour, leads to blindness, symptoms include seeing halos around lights and blurred vision, treatment: eye drops with prostaglandins, b blockers, diuretics
describe the layers of the eyeball including position to one another and function
1) fibrous tunic
outer layer, provides structure
2) vascular tunic
middle layer, allows perception of light
3) retina
neural layer, high acuity area
How many rods and cones per retina?
120 million rods, 6 million cones
differentiate between the function of rods and cones
rods: high sensitivity, night vision, low acuity, vision in shades of grey
cones: low sensitivity, day vision, high acuity, colour vision
What structure facilitates peripheral vision?
rods
Outline the visual pathway.
retina -> ganglia -> optic nerve -> brain
How is visual info sent to the occipital lobe?
via optic radiation
What causes macular degeneration?
build up of waste products, blood vessels growing into retina or pigment epithelial cell death
What layers are affected in retinal detachment?
tearing or separation of pigmented vascular layer and neural layers
Name the 2 muscles in the iris and what it controls
pupillary dilator and constrictor, control how much light enters eye
What is the cornea’s role in light refraction?
fixed focusing ability
What is the lens’ role in light refraction?
adjustable focusing ability, flips image upside down
Describe a myopic eye
eyeball too long, focal point in front of retina
describe a hyperopic eye
eyeball too short, focal point behind retina
Name the starting and finishing structures of the middle ear
tympanic membrane to oval window
what is the function of the tympanic membrane?
to transmit sound to auditory ossicles
Name the 3 parts of the auditory ossicles
malleus, incus, stapes
which part of the auditory ossicles presses against oval window?
stapes
Which structure allows equalisation of pressure in the middle ear?
auditory/pharyngotympanic tube
Which structure does sound exit middle ear via?
oval
window
Name the 2 main structures within inner ear
vestibular apparatus and cochlear
List the 3 chambers of the cochlear.
scala vestibuli, cochlear duct, scala tympani
Describe the pathway of sound from the inner ear to brain
sound pushes tympanic membrane -> pushes cochlear hair cells -> neural signal
List the causes of conduction deafness
compacted ear wax, perforated ear drum, otis media (middle ear inflammation), osteoclerosis (overgrowth bony tissue fuses ossicles together)
describe the causes of senso neural deafness
damage to neural structures, loss of hair cells, stroke, tumours, cochlear nerve degeneration
What is the main function of the inner ear?
allows us to know where we are in space and if we are moving
Describe the function of the semicircular canals in the inner ear
allow detection of rotational or angular acceleration or deceleration
Describe the function of the otolith organs (utricle and saccule) in the inner ear
give us info about position of head relative to gravity and change of linear motion
What lubricates the eyeball and how is it spread across eye?
lacrimal fluid spread by palpebrae
