Anatomy and Physiology 2 Chapter 17 - Ear Anatomy

3 parts of the external ear and its function

1. auricle (pinna)

2. external acoustic meatus (auditory meatus, ear canal): includes ceruminous glands

3. tympanic membrane

collects and directs sound waves to the middle ear

auricle (pinna)

made of cartilage and has foldings so sound waves can travel into the ear

external acoustic meatus (auditory meatus)

ceruminous glands produce cerumen (earwax)

ceruminous glands

earwax provides protection against foreign invaders and funnel sound into the ear; blockage can occur which disrupts sound funneling into the ear

tympanic membrane

ear drum

2 parts of the middle ear and its function

1. bones (malleus, incus, and stapes)

2. muscles (tensor tympani and stapedius)

together with tympanic membrane, sound waves are transformed into vibration and sent to the inner ear

tensor tympani

inserts on the malleus and contraction reduces the amount of malleus movement

stapedius

inserts on stapes and contraction reduces its movement at oval window

3 parts of the inner ear and function of each part

1. semicircular canals: rotation (head movement)

2. utricle and saccule: acceleration and gravity (body movement)

3. cochlea: hearing

the inner ear is a bony labyrinth with __ (2)

1. endolymph: fluid that surrounds the membraneous labyrinth

2. perilymph: fluid that surrounds the bony labyrinth

*lymph movement activates sensory receptors

the vestibular complex is the ___ (2)

1. semicircular canal

2. vestibule (utricle and saccule)

4 parts of the semicircular canal and function

1. anterior duct: up and down movement (yes)

2. lateral duct: lateral movement (no)

3. posterior duct: side to side tilt movement

4. ampulla: expanded duct region

function of ampulla and cupula

when the endolymph moves, the cupula is moved, triggering the hair cells to detect movement and send info to the sensory nerve

4 parts of the vestibule (utricle and saccule) and their function

1. endolymphatic duct: secretes endolymph and connects utricle and saccule

2. endolymphatic sac: excess endolymph to blood

3. maculae: region of vestuble hair cells clusted in - utricle macula (sensitive to horizontal movement) and saccule macula (sensitive to vertical movement)

4. otolithic membrane: hair cells embedded in gelatinous structure in macula

5. otoliths: calcium carbonate crystals taht sit on top of otolithic membrane (move gelatinous material and changes pressure)

3 parts of the cochlea and their function

1. scala vestibule: chamber with perilymph receiving pressure

2. scala tympani: chamber with perilymph pressure going “out”

3. cochlear duct (scala media): chamber with spiral organ

3 parts of the spiral organ in the cochlear duct and their function

1. hair cells: embedded in epithelial cells

2. basilar membrane: holds hair cells

3. tectorial membrane: what hair cells press against when basilar membrane disturbed