Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
28 Cards in this Set
- Front
- Back
|
External Ear
|
-Function = collect sounds
-Auricle or pinna -External auditory canal -Ceruminous glands -tympanic membrane or eardrum |
|
|
Auricle or pinna
|
elastic cartilage covered with skin
|
|
|
External auditory canal
|
curved 1” tube of cartilage and bone
|
|
|
Ceruminous glands
|
Located in epidermis
produce cerumen = ear wax |
|
|
Middle Ear
|
Air filled cavity in the temporal bone
Bordered by tympanic membrane, round window and oval window Three ear bones Auditory tube leads to nasopharynx Helps to equalize pressure on both sides of eardrum |
|
|
Three ear bones
|
Malleus
Incus Stapes |
|
|
Inner Ear -
|
Bony Labyrinth
Membranous Labyrinth |
|
|
Inner Ear - Bony Labyrinth
|
Set of tubelike cavities in temporal bone
semicircular canals, vestibule, and cochlea lined with periosteum and filled with perilymph surrounds & protects membranous labyrinth |
|
|
Inner Ear - Membranous Labyrinth
|
Set of membranous tubes
Contain sensory receptors for hearing and balance Filled with endolymph Utricle, saccule, semicircular ducts, and cochlear duct |
|
|
Cochlear Anatomy
|
fluid filled channels found within the cochlea
scala vestibuli, scala tympani and cochlear duct Oval window connects with scala vestibuli |
|
|
Flow of Sound
|
Stapes vibrates oval window and endolymph in scala vestibuli
At helicotrema, vibration moves into scala tympani Fluid vibration dissipated at round window which bulges The central structure is vibrated (cochlear duct) |
|
|
Cochlear Cross Section
|
Partitions that separate the channels are Y shaped
Vestibular and basilar border the cochlear duct Supported on basilar membrane is the Organ of Corti Converts vibrations into nerve impulses |
|
|
Anatomy of the Organ of Corti
|
Epithelial tissue
Contain 16,000 hair cells have 30-100 stereocilia (microvilli ) Microvilli make contact with tectorial membrane Flexion of microvilli triggers associated nerves to fire |
|
|
Auditory Pathway
|
Cochlear branch of CN VIII sends signals to medulla oblongata
differences in the arrival of impulses from both ears, allows us to locate the source of a sound Fibers ascend to the inferior colliculus (mesencephalon – relay) Thalamus (diencephalon – relay) primary auditory cortex in the temporal lobe (telencephalon) |
|
|
Deafness
|
Sensory deafness
Conduction deafness Neuronal deafness |
|
|
Sensory Deafness
|
Sensory deafness
Damage or destruction of hair cells Once damaged, hair cells do not regrow Hearing aid just amplify sound for damaged hair cells Cochlear implants “mimic” normal hair cells if hair cells are totally destroyed |
|
|
Conduction Deafness
|
Conduction deafness
perforated eardrum otosclerosis |
|
|
Neuronal deafness
|
Problem with brain
|
|
|
Physiology of Equilibrium
|
Static equilibrium
Dynamic equilibrium |
|
|
Static equilibrium
|
Static equilibrium
maintain the position of the body (head) relative to the force of gravity macula receptors within saccule & utricle |
|
|
Dynamic equilibrium
|
maintain body position (head) during sudden movement of any type: rotational, linear, deceleration or acceleration
crista receptors within ampulla (rotational) macual receptors (linear) |
|
|
Vestibular Apparatus
|
Utricle and Saccule
Static equilibrium and linear acceleration Semicircular ducts with ampulla Rotational movement (driving around a corner, doing a cartwheel) |
|
|
Otolithic Organs:
|
Saccule & Utricle
|
|
|
Saccule & Utricle
|
Patch of hair cells in each chamber
Macula saccule and macula utricle Supporting cells secrete gelatinous layer otolithic membrane Otolithic membrane contains calcium carbonate crystals Otholith Helps increase density/inertia of membrane |
|
|
Detection of Position of Head
|
Movement of head causes otolithic membrane and crystals to move
Causes flexion of cilia/sterocilia of hair cells, which triggers neurons to fire an impulse |
|
|
Ampulla - Crista
|
Small elevation within each of three semicircular ducts
anterior, posterior & horizontal ducts detect different movements Hair cells covered with cupula of gelatinous material No otholiths Rotation causes fluid in canal to push cupula Causes flexion of hair cells that trigger neurons to signal |
|
|
Detection of Rotational Movement
|
When head moves, the attached semicircular ducts and hair cells move with it
endolymph fluid does not and bends the cupula and enclosed hair cells Nerve signals to the brain are generated indicating which direction the head has been rotated |
|
|
Equilibrium Pathways in the CNS
|
Fibers from vestibulocochlear nerve (VIII) end in the cerebellum (metencephalon)
Fibers from these areas connect to: cranial nerves that control eye and head and neck movements (III,IV,VI & XI) Spinal nerves that adjust postural skeletal muscle contractions in response to head movements Cerebellum receives constant updated sensory information which it sends to the motor areas of the cerebral cortex motor cortex can adjust its signals to maintain balance |
