Anatomy and Physiology

Question 1

External Ear parts

Answer 1

• Pinna/Auricle
• Ear canal/auditory canal
• surfaces of the ear drum

Question 2

Pinna/Auricle

Answer 2

• the part we see on the side of the head
• fibrocartilage
• connected to surrounding parts by ligaments, muscles, and fibrous tissue
• continues with the skin

Question 3

Ear canal/auditory canal

Answer 3

• runs btw. the pinna and the ear drum
• made up of cartilage, membrane and bone
• 1-2.5cm long and 0.5cm in diameter
• outer part of the canal is made up of cartilage
• inner part is made up of bone and is surrounded by skin
• skin of the inner canal contains hair and sebaceous glands for lubrication and produces ear wax
• forms an s shape curve
• cylinder is oval in shape and diameter is greater at the outer area than the inner
• somewhat flexible

Question 4

Ear wax issues in ear canal

Answer 4

• glands produce ear wax/cerumen which helps prevent dirt and small particles from entering the ear and discourages growth of bacteria
• canal can become completely plugged with wax and conductive hearing loss can occur
• stenosis can happen

Question 5

Stenosis

Answer 5

• when the ear canal becomes very narrow due to injury and infection

Question 6

Terminal part of external ear

Answer 6

• eardrum/tympanic membrane

Question 7

External ear function

Answer 7

• collects and directs sound waves into the ear canal and ear drum
• protects the ear drum
• can be subjected to skin disorders lime dermatitis

Question 8

Middle ear parts

Answer 8

• air filled cavity that has the mastoid cells (sound conducting mechanism) –> hammer (malleus), anvil (incus), stirrup (stapes)
• Eustachian tube

Question 9

Hammer/Malleus

Answer 9

• attached to the ear drum on one side with the anvil on the other

Question 10

Sound conducting mechanism

Answer 10

• has the three smallest bones
• hammer (malleus), anvil (incus), stirrup (stapes)

Question 11

Anvil/Incus

Answer 11

• attached to the stirrup which is attached to the oval window

Question 12

Ossicles

Answer 12

• hammer (malleus), anvil (incus), stirrup (stapes)
• held into place by ligaments and muscles
• specific muscles include the tensor tympani and stapedial muscles

Question 13

Tensor tympani and stapedial muscles

Answer 13

• stiffens the ear drum to protect the ear drum from loud noise

Question 14

Eustachian tube

Answer 14

• connects the middle ear to the back of the nose and throat
• when open it maintains equal pressure on each side of the ear drum
• can temporarily close due to allergies, colds, and infections
  
  • causes a feeling of fullness and discomfort b/c of pressure imbalances btw the outside and inside pressure of the middle ear

Question 15

Middle ear disorders

Answer 15

• otosclerosis, perforated ear drum, break in the ossicles

Question 16

Otosclerosis

Answer 16

• a bony growth that immobilizes one or all of the bones
• caused by loud noises or a hit to the head

Question 17

conductive hearing loss

Answer 17

• hearing loss due to a middle or outer ear problem

Question 18

How does sound travel from the outer to the inner ear?

Answer 18

• middle ear conducts sound energy from the outer to inner ear
• sound waves strike the ear drum, ossicles vibrate, stirrup vibrates the oval window
• as sound travels it is amplified b/c the oval window is smaller, the ossicles act as mechanical transformers and levers that increase sound energy to the inner ear

Question 19

Inner ear parts

Answer 19

• bony and membranous labyrinth
• cochlea
• vestibule
• semicircular canals
• balance organs
• cochlear duct
• sensory mechanism for both hearing and balance

Question 20

Bony labyrinth

Answer 20

• contains the cochlea, vestibule, and semi-circular canals
• filled with perilymph which houses the membranous labyrinth

Question 21

Membranous labyrinth

Answer 21

• contains the balance organs and cochlear duct
• filled with endolymph

Question 22

Sensory mechanism

Answer 22

• hearing and balance

Question 23

Cochlea

Answer 23

• sensory mechanism for hearing
• snail shaped
• connected to vestibule
• tiny hair cells attached to nerve endings
• nerve endings are attached to the 8th cranial nerve (auditory nerve)
• frequency sensitive
• higher frequencies are detected at the oval window at the base of the cochlea
• lower frequencies detected at apex of cochlea

Question 24

vestibule

Answer 24

between the cochlea and the semi-circular canals

Question 25

semicircular canals

Answer 25

help with balance

Question 26

oval window

Answer 26

- where the stapes is located - where sound presses on the inner ear

Question 27

sound movement through the oval window

Answer 27

- ossicular movement causes vibrations in the fluid of the cochlea - vibrating fluids cause the hair cells to vibrate - sound it transmitted to the brain

Question 28

round window

Answer 28

- exit point for sound pressure - provides a pressure release mechanism

Question 29

sensorineural hearing loss

Answer 29

- exposure to too much noise for too long - damages the hair cells = hearing loss - other causes include infection, cochlear injury, and oto-toxins (agents that can damage the inner ear as a side effect) - most common is noise exposure and aging