The Ear

Question 1

External Ear:

Answer 1

1. Auricle (aka Pinna):
   - skin, fat, and elastic cartilage funnels sound waves and helps in localization.
2. External auditory meatus

Question 2

Middle Ear:

Answer 2

1. Tympanic membrane (aka ear drum)
2. Auditory ossicles:
   - malleus (hammer);attached to tympanic membrane
   - Incus (anvil); forms small synovial joint
   - Stapes (stirrup); moves in the “oval (vestibular) window” of the cochlea
3. Auditory (aka Eustachian) tube; cartilaginous airway to the nasopharynx; equalizes air pressure

Question 3

Inner Ear (labyrinth):

Answer 3

-fluid filled tubes and chambers within temporal bones

Question 4

Vestibular complex (inner ear):

Answer 4

1. filled with endolymph (fluid) from cochlear duct.
2. sends sensory information via vestibular division of vestibulocochlear nerve (VIII):
   A). Vestibule (utricle and saccule): contains receptors (maculae) to detect the position of the head. “static equilibrium”
   B). Semicircular canal (3):
   -oriented at right angles; one for each plane
   -contain crest of hair cells (cristae) within each ampulla, responding to head movement. “dynamic equilibrium”

Question 5

cochlea (inner ear):

Answer 5

1. Three parallel tubes within cancellous bone
2. Scala vestibuli:
   - continuous with–>scala tympani
   - contains perilymph fluid
   - conducts fluid pulsations from the oval (vestibular) window to the round (cochlear) window
3. scala media (cochlea duct) houses the spiral organ filled with endolymph

Question 6

spiral organ (organ of corti)

Answer 6

• extends down the length of the scala media.
• sensory hair cells mounted along basilar membrane
• hairs embedded in over overhanging tectorial membrane

-vibration of basilar membrane results in movement of hair cells which is converted into electrical impulses carried to the brain via the cochlear division of the vestibulocochlear nerve (VIII)