Section 4 Flashcards
1
Q
The ear is divided into three sections:
A
- inner ear
- middle ear
- external ear
2
Q
Describe briefly the external ear
A
- represents the structure of the ear you can touch
- sound waves from the environment travel through the external auditory canal to reach the tympanic membrane, causing it to vibrate
- ceruminous glands are microscopic and secrete ear wax
3
Q
What is the tympanic membrane?
A
- AKA the eardrum
- marks the boundary between the external and middle ear
- transmits sound from the external environment to the ossicles of the middle ear
4
Q
What impact is the perforated tympanic membrane likely to have on hearing?
A
- The effect is decreased or disrupted hearing
5
Q
Briefly describe the middle ear
A
- located within the temporal lobe
- spans from the tympanic membrane to the oval window
- sound waves involved with hearing are also transmitted through the middle ear
6
Q
Describe the parts of the middle ear
A
- Ossicles: small bones located in the middle ear
- Tympanic cavity: chamber in the temporal bone
- Round and oval windows: Areas at which the middle ear connects to the inner ear
- Eustachian tube: Connects the middle ear to the nasopharynx
7
Q
What are the ossicles, and what muscles are attaches to them?
A
- The ossicles are three small bones located in the middle ear
- they help transmit sound waves to the receptors in the inner ear
- the muscles attached to the ossicles (the tensor tympani and the stapedius) function to dampen very loud noises
8
Q
What are the three ossicles?
A
- Malleus (hammer): the most lateral ossicle that is attached to and behind the tympanic membrane
-Incus (anvil): sits between the malleus and the stapes - Stapes (stirrup): the smallest bone and sits in the oval window. It is about 1/3 the mass of the other ossicles. (also looks like a stirrup)
9
Q
What are the labyrinths, and where are they?
A
- Both the cochlea and vestibular apparatus are structured as two channels in the bone, called labyrinths (the membranous and bony labyrinths)
- the membranous labyrinth is within the bony labyrinth
- both labyrinths are filled with fluids that allow us to hear (cochlea) or become aware of and monitor the position of our head (vestibular apparatus)
- the membranous labyrinth is filled with endolymph and the bony labyrinth is filled with perilymph
10
Q
What is the vestibular apparatus and what is it composed of?
A
- The vestibular apparatus contains the receptors for equilibrium
- Composed of three structures:
1. semicircular canals: detect rotational movement (head moving up and down, side to side and tilting)
2. utricle
3. saccule: detect positional movement (head moving from one point in space to another, with respect to gravity and linear acceleration)
11
Q
What is the cochlea and what is it composed of?
A
- contains the receptors for hearing
- composed of three ducts: the vestibular duct, the tympanic duct, and the cochlear duct
12
Q
Describe the organs of Corti
A
- A specialized structure integral to hearing
- Found in the cochlear duct of the cochlea
- made up of specialized cochlear hair cells that rest on a basilar membrane
- when the membrane is moved by sound waves, the hair cells fire an impulse, which is sent to the brain via CN VIII for interpretation