Module 3 - Nervous System: Auditory and Vestibular Systems Flashcards
Auricle (External Ear) (5)
1) Shaped to funnel sound waves
2) Can be seen externally
3) Composed of elastic cartilage, covered with skin
4) Rim (helix)
5) Lobule (lack of cartilage)
External Acoustic Meatus (External Ear) (3)
1) Tunnel between auricle and tympanic membrane
2) Composed of elastic cartilage near auricle and becomes a cylinder through the temporal bone
3) Lined with skin with hairs and glands that secrete cerumen (wax)
Tympanic membrane (External Ear) (3)
1) Canal terminates here
2) Thin membrane of connective tissue
3) Vibrates with sound, transmits sound energy to the middle ear
Tympanic Cavity (Middle Ear) (3)
1) Air filled chamber
2) Three bones
a) Malleus (hammer)
b) Incus (anvil)
c) Stapes (stirrup)
3) Malleus receives vibrations from tympanic membrane and conveys them towards the inner ear
Bony Labyrinth (Inner Ear) (2)
1) Fluid filled
2) Components
a) Vestible
b) Semicircular canals
c) Cochlea (looks like a snail)
Membranous Labyrinths (2)
1) Fluid filled
2) Components
a) Lie within the bony labyrinth
b) Utricle and Saccule (tiny stones inside that help with balance and equilibrium
Vestibular System (Inner Ear-Balance) (3)
1) Three Semicircular Canals
a) Fluid filled
2) Each canal contains equilibrium receptors
a) Action potentials in response to different head movements or rotation
3) Impulses sent along the vestibular portion of CN VIII
Cochlea (Inner Ear-Hearing) (3)
1) Spiral, bony chamber
2) Contains the membranous endolymph-filled cochlear duct
3) Houses organ of Corti and terminates at the cochlear nerve
Organ of Corti (Inner Ear-Hearing) (4)
1) Tectorial membrane
a) Sterocilia (tiny hairs)
2) Fluid receives vibrations and bends attached stereocilia
3) Mechanical movement initiates actions potential
4) Carried through the Cochlear nerve portion of CN VIII
Vestibulocochlear Nerve (Inner Ear) (2)
1) Vestibular branch - connected to semicircular canals
2) Cochlear branch - connected to cochlea
Facial Nerve (Inner Ear) (4)
1) CN VII also located in inner ear
2) Innervates stapedius muscle - attached to stapes
3) Controls amount of tension on the bone allowing for increased or decreased vibrations
4) Controls intensity of sounds (ears adjust to a loud concert because this nerve adjusts tension)
Hearing pathway
1) Cochlear nerve
2) Primary auditory cortex of the temporal lobe
3) Unique pathway - pathways cross to opposite side of the brain AND sends signals to the same side
Deafness types (2)
1) Partial
a) Impaired but not completely lost
2) Total
Conduction deafness (4)
1) Damage to outer or middle ear structures
2) Ceremun build up
3) Ossicle bone fusion
4) Partial
Nerve deafness (4)
1) Damage to nerve pathway
2) Receptor cells
3) Cochlear nerve or brain
4) Can be partial or complete
