Special Senses- Ear Flashcards
Ear provides input for 2 senses
- Equilibrium- informs us of position of body in space by monitoring gravity, linear acceleration and rotation
- Hearing- enables us to detect and interpret sound waves
Regions of war
3
External ear
Gathers sound
Ear drum out- pinna, external auditory canal, ten panic membrane
Middle ear
Produces sound- behind eardrum ( ossicles- malleus, incus, stapes)
Inner ear
Interprets sound- within occipital bone
Outer
Pinba
MAde of cartlidge and skin and shaped like a funnel
Collects and directs sound into ear canal
Outer
External auditory canal
Tunnel that begins at external and extends inward towRd ear drum, lined with hairs
Outer
Tempanic membrane
Eardrum
Middle - between cochlea and ear drum
Auditory tube - 3 main functions ( runs mid ear down into throat)
- Equalize pressure between middle ear and nasopharyngeal ( ears popping)
- Protects middle ear from nasopharyngeal secretion and loud sound
- Ventilation and drainage of middle eAr
Balances air pressure at both sides of ear drum
Middle
Ossicles- conductive portion of hearing
Malleus- attached to tempanic membrane
Incus- trunk, connector function
Stapes- smallest bone in body, footplate inserts in oval window
Intensifies vibration of sound wave by 22 times enforce transmitting to oval window
Amplified of TM to smaller areas enables vibration of cochlear fluid
Vibrations equal energy
Oval window
Within vestibule- base of semicircular canals
Between middle and inner, transmits sound vibrations
Muscles of middle ear
Stapedius
Smallest skeletal muscle in the human body connected to stapes
Contacts- reduces stapes action( reduce amplification)
Contracts before speaking/chewing
Innervated by facial nerve VII
Internal ear
In temporal bone
Cochlea
Where hearing happens
3 chambers- vestibular (top), tempanic (bottom) cochlear duct ( middle)
Vestibular apparatus
Balance receptors
Vestibule
Base for semicircular canals
Organ of Corti electromechanical sensitive hair cells- hearing organ,needs activate to activate brai. Found in cochlea
Vestibulocochlear nerve CN 8
Carries impulse to brain which interprets the impulse as sound
Cochlear Canals are hollow
Filled with perilymph- excellent at transmitting energy(waves)
Hearing pathway
Receptor (organ of corti)— CN 8- vestibulocochlear— brain stem— thalamus— temporal lobe— cerebral cortex—
Equilibrium
2 types
Static- standing/sitting/laying- receptors in vestibule. Maintenance of position of body ( mainly head) relative to force of gravity
Saccule and urticle (organs) monitor static equilibrium, located in vestibule and contain macula- sensory organ
Otolithic membrane of saccule and urticle contains crystals (otoliths)— ear stones, and make it top heavy- monitored in internal ear with head movement ( back and forth)
Dynamic- moving. Receptors in semicircular canals. Maintenance of body position I response to sudden movement
Vestibular apparatus maintains the body at equilibrium and stabilizing eyes relative to movement
Canals contain crista ( flexible membrane) made of hair like cell and supporting cell covered by jelly like material (cupola)— movement stimulates hair cells
Semicircular canals
Hollow and contain endoliph (fluid) rotate body, fluid moves ( level bubble)
Ballooned out part where all canals meet us the ampulla
Neurological pathway (vestibular) equilibrium— most complex- not direct
Receptor ( saccule/ urticle) — vestibulocochlear nerve— brain stem- CN 6,4,3– impulse to vestibular area
