Ear 1

Question 1

Name the 3 regions the ear is divided into

Answer 1

external (outer) ear
middle ear
internal (inner) ear

Question 2

Describe the function of the external/outer ear

Answer 2

to collect sound waves and direct them inwards

Question 3

Name the 3 parts the external ear consists of

Answer 3

Pinna/Auricle
External Auditory Canal/Meatus (EAM)
Tympanic Membrane

Question 4

Describe the pinna/auricle

Answer 4

flap of elastic cartilage covered in thick skin

Question 5

Describe the EAM - external auditory meatus

Answer 5

2.5cm curved tube in the temporal bone that leads to the tympanic membrane, hairs and sebaceous glands which secrete cerumen (ear wax) near the exterior opening prevent objects from entering the ear

Question 6

Describe the tympanic membrane (eardrum)

Answer 6

thin, semi-transparent partition between the EAM and middle ear, concave external surface covered with skin, convex internal surface covered with mucous membrane

Question 7

Describe the middle ear

Answer 7

an air filled cavity within the petrous portion of the temporal bone, separated from the external ear by the tympanic membrane, separated from the internal ear by a thin body partition containing 2 openings = oval window and round window

Question 8

Describe how the Auditory/Eustachian tube fits in

Answer 8

the anterior wall of the middle ear contains an opening that leads directly to the Eustachian tube, connects the middle ear with the nasopharynx

Question 9

Describe the function of the Auditory/Eustachian tube

Answer 9

to equalise air pressure on both sides of the tympanic membrane, otherwise rupture of this membrane can occur, also a route for pathogens to travel from the nose and throat to the middle ear - can lead to infection such as otitis media

Question 10

Name where the auditory ossicles lie and their names and shape

Answer 10

lie within the middle ear, 3 smallest bones in the body
The malleus (hammer)
The incus (anvil)
The stapes (stirrup)

Question 11

Describe how the auditory ossicles are connected, attached and their roles

Answer 11

connected to each other by synovial joints, the ossicles are attached to the cavity by ligaments and muscles, they reduced the amplitude and range of oscillations within the ear to protect it from damage due to loud noise

Question 12

Describe how each auditory ossicle is attached

Answer 12

the handle of the malleus is attached to the internal surface of the tympanic membrane, the head of the malleus articulates with the body of the incus, the incus articulates with the head of the stapes, the base of the stapes fits into the oval window which sits between the middle and inner ear, below the oval window is the round window

Question 13

Describe the inner ear

Answer 13

also known as the labyrinth, a complex series of canals that form the bony and membranous labyrinth, located in the petrous portion of the temporal bone

Question 14

Name the 3 series of cavities the bony labyrinth is divided into

Answer 14

vestibule
cochlea
semicircular canals

Question 15

What are all 3 cavities filled with

Answer 15

fluid called perilymph

Question 16

Describe the membranous labyrinth

Answer 16

the perilymph of the bony labyrinth surrounds the membranous labyrinth, its a series of sacs and tubes lying insde and following the same form as the bony labyrinth

Question 17

What does the membranous labyrinth contain

Answer 17

endolymph

Question 18

Describe the semicircular canals

Answer 18

3 bony canals that project upward and posteriorly from the vestibule , each lie at approx right angles to each other, due to their positions = called anterior, posterior and lateral semicircular canals, the ends of each enlarge into a swelling called the ampulla
the membranous labyrinth within the canals are the semicircular ducts

Question 19

Describe the cochlea

Answer 19

lies anterior to the vestibule, shell-like appearance, 2 & 3/4 turns, contains hair cells that act as receptors for auditory sensation, the free ends of the hair cells extend into the endolymph of the membranous labyrinth, the basal ends of these cells are in contact with the fibres of the cochlear branch of vestibulocochlear nerve (CNVIII)