Special Senses Flashcards
Eyeball has 6 primary components
- fibrious tunic
- vascular tunic
- nervous tunic (retina)
- lens
- anterior segment
- posterior segment
Fibrous tunic consists of ..
- sclera
- cornea
- conjunctiva
Sclera
avascular CT (white)
Cornea
avascular CT (transparent)
Conjuntiva
covers anterior surface of sclera, vascular mucous membrane (dilated vessels = bloodshot eyes)
Vascular tunic parts
- choroid
- ciliary body
- iris
- pupil
Choroid
contains melanin which prevents the reflection and scattering of light, highly vascular (posterior)
Ciliary body
ciliary muscle and ciliary processes, which controls the space of the lens and secrete aqueous humor
Iris
coloured part of eye
Pupil
hole in iris
Nervous tunic (retina) consists of the
- outer pigmented layer
- inner neural layer
- fovea centralis
- optic disc
Inner neural layer of retina’s 3 layers
- photoreceptors neurons
- bipolar cells
- ganglion cells
2 types of photoreceptors
- rods (black and white)
- cones (color)
Ganglion cells
axons from optic nerve (cranial nerve ll)
Fovea centralis
where light is focused, area of greatest visual acuity, no rods only cones
Optic disc
blind spot where blood vessels and optic nerve exit eye. no cones or rods
Lens
avascular, transparent
Cataracts =
clouding of lens
Anterior chamber
anterior to lens, contains aqueous humor (fluid similar to plasma) which drains into sinus located at junction between cornea and sclera
Posterior segment
posterior to lens, contains vitreous humor (gel like) and not replaced
Structural features of the ear
- external ear
- middle ear
- inner ear
- cochlea
External ear
conducts sound
Parts of external ear
- auricle
- auditory canal (meatus)
- tympanic membrane (eardrum)
Auricle/ pinna
elastic cartilage, covered in skin
Middle ear functions to
conducts sound
Parts of inner ear
- bony labyrinth
- membranous labyrinth
- vestibular nerve
Bony labyrinth lined with ..
periosteum and contains perilymph
Bony labyrinth contains the
- semicircular canals (equilibrium)
- vestibule (equilibrium)
- cochlea (hearing)
Membranous labyrinth contains what lymph
contains endolymph
Membranous labyrinth contains the ..
- semicircular duct
- utricle and saccule
- cochlear duct
Semicircular duct
inside canals and connects with the utricle
Utricle and saccule
inside vestibule
Cochlear duct
inside cochlea
Cochlea is a
coiled structure (2.5 coils)
Each cochlea coil has 3 channels
- scala vestibuli
- scala tympani
- scala media
Scala vestibuli
upper; perilymph and part of bony labyrinth
Scala tympani
lower; perilymph and part of bony labyrinth
Scala media
(cochlear duct) middle. continuation of membranous labyrinth. contains endolymph in all three membranes
Membranes of cochlea
- vestibular membrane
- basilar membrane
- tectorial membrane
Vestibular membrane
separates the cochlear duct and scala vestibuli
Basilar membrane
separates the cochlear duct and scala tympani
Tectorial membrane
cover hair cells of spiral organ
Receptors in inner ear
hair cells that synapse with neurons
Hair cells in inner ear send..
impulses to brain via cranial nerve Vlll (vestibulcochlear nerve)
Hairs of inner ear
cilia that extend to extend into endolymph
Middle ear consist of the 3 auditory ossicles and what tube
- malleus (against tympanic membrane of external ear)
- incus
- stapes (against oval window of inner ear)
- eustachian tube (auditory tube)
Functions of the ear include
- conduction of sound
- hearing and equilibrium (inner ear)
