1. Ch 10 PNS, Part 4 (Hearing) Learning Objectives
Lend me your ear.
Ch 10 PNS, Part 4 (Hearing)
Learning Objectives
Be able to identify the structures of the ear (all)
Discuss the bones of the middle ear
Explain how we hear
Explain the mechanisms of balance & equilibrium in the ear

2. CSI: Can You Spot the Ear?
More info please >

3. Vacanti Mouse
It might look like the work of a mad scientist but the Vacanti mouse with what appears to be a human ear growing on its back is the real deal. You won't find this mouse at the circus; it was created at the University of Massachusetts in Dr. Charles Vacanti developed the mouse by putting a mold resembling the shape of a human ear onto its back.
Dr. Vacanti is helping researchers fine tune a technology that will let them re-grow ears and noses for people. It was a plastic surgeon who suggested growing ears on mice after seeing kids who were born with out ears or who'd had them torn off in accidents.
The 'ear' mold was made from special fibers that are biodegradable, much like dissolving stitches that doctors often use. Before the mold is implanted into the back of a hairless mouse, it is covered with cow cartilage cells. Blood from the mouse helps the cartilage cells grow and eventually replace the fibers. Researchers say that the rodent could have the ear removed and still remain alive and healthy.

4. Practice Activity: How Well Do You Know The Parts of the Ear?
Answer question #10, Page 211 in your workbook now.

5. Hearing and Balance Pgs 210-211
The three parts of the ear are the ______, ______, and ________ ear
The outer and middle ear are involved with _______
The inner ear functions in both hearing and ________
Receptors for hearing and balance:
Respond to separate stimuli
Are activated independently

6. Outer, Middle and Inner Ear
Label or bracket the three regions of the ear: outer, middle and inner on your diagram.

7. Outer Ear The auricle or ______ is composed of:
The helix (rim)
The lobule (earlobe)
External auditory canal
Short, curved tube filled with ceruminous or ____ glands
Tympanic membrane or ________
Thin connective tissue membrane that vibrates in response to sound
Transfers sound energy to the middle ear ossicles
Boundary between outer and middle ears
pinna
wax
eardrum

8. Middle Ear A small air-filled mucosa-lined ______
Flanked laterally by the ________
Flanked medially by the oval and round windows
Pharyngotympanic tube – connects the middle ear to the nasopharynx
_______ ________ in the middle ear cavity with the external air pressure
cavity
eardrum
Equalizes pressure

9. Middle Ear

10. Bones of the Middle Ear
The tympanic cavity contains three small bones: the ______,______, and ______.
Transmit vibratory motion of the eardrum to the oval window
malleus
incus
stapes
These bones are formally named the "malleus", the "incus", and the "stapes", but they are more commonly known as the "hammer", the "anvil" and the "stirrup".
Porpoise inner ear bones

11. Inner Ear ______ labyrinth __________ labyrinth
Tortuous channels worming their way through the temporal bone
Contains the _________, the __________, and the _________________
Filled with fluid called _________
__________ labyrinth
Series of membranous sacs within the bony labyrinth
Filled with a potassium-rich fluid
Bony
vestibule
cochlea
semicircular canals
perilymph
Membranous

12. Vestibule The central egg-shaped cavity of the bony labyrinth
Suspended in its perilymph are two sacs: the saccule and utricle
The saccule extends into the cochlea
The utricle extends into the semicircular canals
These sacs:
House equilibrium receptors called maculae
Respond to gravity and changes in the position of the head

13. Semicircular Canals
Three canals that each define two-thirds of a circle and lie in the three planes of space
Membranous semicircular ducts line each canal and communicate with the utricle
The ampulla is the swollen end of each canal and it houses equilibrium receptors in a region called the crista ampullaris
These receptors respond to angular movements of the head

14. Cochlea A spiral, conical, bony chamber that:
Extends from the anterior vestibule
Coils around a bony pillar called the modiolus
Contains the cochlear duct, which ends at the cochlear apex
Contains the organ of Corti (hearing receptor)

15. Internal Ear Anatomy
Instructions: Label the malleus, incus, stapes, eardrum, cochlea, vestibule, and semicircular canals on your practice diagram now.

16. How Do We Hear? Sound vibrations beat against the eardrum
The eardrum pushes against the ossicles, which presses fluid in the inner ear against the oval and round windows
This movement sets up shearing forces that pull on hair cells
Moving hair cells stimulates the cochlear nerve that sends impulses to the brain

17. Hearing & Balance

18. Balance & Equilibrium Vestibular apparatus – __________
in the semicircular canals and vestibule
Maintains our _________________ in space
Vestibular receptors monitor static equilibrium
Semicircular canal receptors monitor dynamic equilibrium
equilibrium receptors
orientation and balance

19. Balance & Equilibrium continued
Maculae are the sensory receptors for static equilibrium
Contain supporting cells and hair cells
Otolithic membrane is a jellylike mass studded with tiny CaCO3 stones called _________
Utricular hairs respond to ________movement
Saccular hairs respond to _______ movement
otoliths
horizontal
vertical