Anatomy - Ear

Question 1

Different parts of the ear

Answer 1

• external: cartilage, tube
• middle: cavity, bone, muscles
• internal: canal, sacs
• external and middle ears are mechanical - pass on the sounds
• internal ear is electrical - processes the sound

Question 2

External ear 2 parts

Answer 2

• auricle

- external acoustic meatus

Question 3

External ear

1) Auricle

Answer 3

• parts: skin, cartilage, ligaments, mucles
• nerves: V3, C2-3
• Function: protection, localise sound

Question 4

External ear:

2) external acoustic meatus

Answer 4

• 1 inch long, not straight, concave anteriorly
• parts: lateral 2/3 are cartilaginois made of hairs and glands, medial third is made up of bone
• relations: parotid anteriorally, mastoid air cells posteriorally
• nerves: V3, C2-3
• function: conduct and amplify sound towards tympanic membrane, protects and humidy the air

Question 5

Clinical issues of external ear

Answer 5

• ear viewing

- self-cleaning system

Question 6

Middle ear contents

Answer 6

• tympanic membrane
• ossicles
• muscles
• cavity

Question 7

Middle ear: tympanic membrane

Answer 7

• partitions external and middle ears
• concave laterally
• Surface: distinct covers
• parts: pars tensa attaches to malleus, pars flaccida
• nerves: V3/ X innervate the lateral part of tympanic membrane, IX is very sensitive and innervates the medial part of tympanic membrane
• Functions: receive sounds, first vibrator

Question 8

• clinical issues of tympanic membrane

Answer 8

• color: becomes red when inflammed
• cone of light
• perforations: small ones self correct but larger ones may require surgery

Question 9

Middle ear: ossicles

Answer 9

• types: malleus, incus, stapes (from tympanic membrane to inner ear). Connected by synovial joints
• workings: system of levelrs, some move, others are fixes
• function: transfer vibrations towards inner ear
• CLINICAL ISSUE: commonly infected

Question 10

Muscles of middle ear

Answer 10

• tensor tympani: from auditory tube to handle of malleus
• Stapedius: from posterior cavity to stapes
• Nerves: V3 for tensor, VII for stapedius
• Functions: dampen vibrations of tympanic membrane
• clinical issues: hyperacusis if vibrations are not dampened

Question 11

Internal ear two parts

Answer 11

• osseous labyrinth

- membranous labyrinth

Question 12

Osseous labyrinth

Answer 12

• structure: cavity in temporal bone, contains perilymph

- parts: semicircular canals, vestibule, cochlea

Question 13

Membranous labyrinth structure

Answer 13

• sacs continuous with osseus labyrinth
• closed system
• contains endolymph - important that it doesnt mix with perilymph
• endolymph production requires melanocyte - thats why albino may have trouble hearing

Question 14

Membranous labyrinth: parts

Answer 14

• semicircular ducts (in canals): cupula (kinetic labyrinth - movement)
• utricle and saccule (in vestibule): macula (static labyrinth - position)
• cochlea duct (in cochlea): organ of corti (hear)

Question 15

Membranous labyrinth nerves and function

Answer 15

• nerve: vestibulocochlear. Vestibular to cupula and macula, cochlear to organ of corti
• function: fluid shifts, position, movement, hearing

Question 16

Clinical issues of internal ear

Answer 16

• conductive deafness: external or middle ear
• Sensorineurol deafness: inner ear
• Meniere disease: vestibular and auditory disturbance, mixing of endolymph and perilymph. Occurs because of excessive nause, trauma or virus