Ear

Question 1

Three main divisions of the terrestrial mammalian ear:

Answer 1

External (outer) ear, Middle ear, Inner ear

Question 2

External ear

Answer 2

• auricle (pinna): collects sound waves from environment

- ear canal: vertical and horizontal parts

Question 3

Middle ear

Answer 3

• housed in tympanic part of temporal bone
• tympanic membrane (ear drum)
• tympanic bulla (tympanic cavity)
• auditory ossicles e/ associated muscles and ligaments
• communicates w/ nasopharynx via the auditory tube

Question 4

Inner ear

Answer 4

• responsible for balance(semicircular canal)
• Housed in petrous part of temporal bone
• osseous labyrinth
• membranous labyrinth (organs of inner ear)

Question 5

Three divisions of ear allow for transformation of sound pressure waves into electrical energy

Answer 5

• external ear captures sound waves & transmits energy to the middle ear via tympanic membrane
• ossicles of middle ear convert these pressure waves into mechanical energy
• vibrations at oval window by the stapes produces pressure waves e/in perilymph of inner ear
• movement of perilymph displaces the tectorial and basement membranes, stimulating firing of electrical impulses by cochlear neurons

Question 6

The external ear is necessary for sound collection and sound localization

Answer 6

• visible portion of external ear is supported by irregularly shaped auricular cartilage
• proximal end of this cartilage forms a canal (vertical and horizontal ear canals)
• distal end of this cartilage forms pinna, funnel to concentrate waves

Question 7

Shape of pinna is dependent upon

Answer 7

• the composition of the fibroelastic auricular cartilage
• the collagen/elastin composition varies among species and breeds
• non-erect, erect, semi-erect
• size & shape determines which sound frequencies are collected optimally and also many reduce noise
• vasculature helps cool body

Question 8

What gland produces ear wax?

Answer 8

ceruminous gland

adenomoas in cats

Question 9

Where do ticks like to collect?

Answer 9

cutaneous marginal pouch

Question 10

Annular cartilage

Answer 10

holds ear to skull

-connects cartilagenous meatus of horizontal canal w/ bony external acoustic meatus

Question 11

Scutiform cartilage

Answer 11

“sesmoid bone” attachment for auricular muscles and tendons

• flat, boot-shaped cartilage
• located medial & rostral to base of auricle
• aids in redirection

Question 12

Auricular muscle groups that allow auricle of each ear to move towards a sound source

Answer 12

• rostral auricular group

- caudal auricular group

Question 13

The middle ear is located in the air-filled tympanic cavity of the

Answer 13

temporal bone

Question 14

Only connection to external environment occurs through the

Answer 14

auditory tube

Question 15

What is the expanded ventral portion of the tympanic cavity?

Answer 15

tympanic bulla

Question 16

What is the bony promontory?

Answer 16

expansion of the petrous temporal bone

-protrudes into dorsal region of tympanic cavity

Question 17

Manubrium of the malleus is embedded in the

Answer 17

tympanic membrane

Question 18

Vibrations of the tympanic membrane move to the

Answer 18

malleus

Question 19

Contraction of ______ dampens the movement of the malleus

Answer 19

tensor tympani muscle

Question 20

Diarthrotic (synovial) joints connect the middle ear ossicles. Movement of the malleus will result in the movement of

Answer 20

the incus and stapes

Question 21

Contraction of the ________ dampens the movement of the stapes at the oval window

Answer 21

stapedial muscle