BMS271 - Eye & Ear Flashcards
Eyelids (palpebrae)
connective + muscle tissue (muscle opens eyes = levator palpebrae)
lubricated by tarsal glands
closed by orbicularis oculi
Conjunctiva
transparent mucous membrane
covers inner surface of eyelids and anterior eyeball
Conjunctivitis – pink eye, contagious, bacterial, irritation, mechanical, injury
Lacrimal apparatus
lacrimal gland (superiolateral corner)
lacrimal canaliculi + sac (inferiomedial)
Lateral to medial
Extrinsic eye muscles
superior, inferior, lateral and medial rectus
superior and inferior oblique
Anatomy of the Eye
Three layers or tunics:
fibrous, vascular and nervous
Fibrous tunic
sclera (white of the eye)
cornea
Sclera
dense collagenous connective tissue which muscles attach to, firm, posterior 5/6ths of eye
Cornea
clear, avascular connective tissue, allows light to enter, refracts (bends) light rays, injury prone
Vascular tunic
choroid, ciliary body and iris
Choroid
underneath sclera, thin membrane, black
Ciliary body
smooth muscle sphincter attached to lens via suspensory ligaments
Iris
coloured, smooth muscle, regulates pupil size
Neural tunic
retina
macular lutea
Compartments and Lens
The eye is divided into two compartments named the anterior and posterior segments
They are separated by the lens
Lens = transparent, biconvex, epithelial tissue
The anterior segment is filled with fluid called aqueous humor, and is further divided into anterior and posterior chambers (separated by iris/pupil)
The posterior segment is filled with vitreous humor (jelly) and is much larger than the ant. seg.
These fluids help maintain the shape of the eye
Anatomy of Hearing
External, middle and inner ears
External ear
auricle external acoustic meatus tympanic membrane Tragus = little bit that does nothing Auricle or pinna = ear Lobule = ear lobe
Middle ear
Middle ear
- air filled space connected to pharyngotympanic tube
- ossicles = malleus, incus, stapes
- Middle ear separated from inner ear by round and oval windows
- Oval window deep to stapes
Inner ear
bony and membranous labyrinths (canals in bone filled with fluid, membranes and receptors)
Cochlear
Semicircular canals
Hearing
Soundwaves arrive at the tympanic membrane and cause it to vibrate
This in turn causes vibration of the malleus (hammer), incus (anvil) and stapes (stirrup)
The stapes is attached to the oval window of the cochlea (snail shell)
Vibration at the oval window causes vibration in the fluid inside the cochlea, which causes deformation (change in shape) of the basilar membrane
Hair cells (sensory receptors) in the membrane send action potentials in response to this deformation
Hearing loss
Conductive – problem with getting sounds waves, external, middle ear
Sensory neural loss – damage to nerve or cochlear
