Chapter 15 Balance Flashcards
What part of the ear involves balance?
The inner ear
The inner ear functions in …
Hearing and equilibrium
Where is the inner ear located?
Posterior to eye orbit , petrous portion of temporal bone
What are the 3 regions of the inner ear?
Cochlea, vestibule, semicircular canals (anterior to posterior)
Series of bony cavities with temporal bone
Bony labyrinth
What lines the bony labyrinth?
Endosteum
What fluid is contained in the bony labyrinth?
Perilymph
What is suspended within the bony labyrinth?
Membranous labyrinth
The membranous labyrinth is filled with ____ and surrounded by ____
Endolymph and perilymph
What is fluid like K+ rich icf
Endolymph
What does the membranous labyrinth consist of? (3 parts)
Cochlear duct, saccule and Utricle, and semicircular ducts
What conducts sound vibrations in hearing and respond to mechanical forces during body position changes and acceleration?
Fluids
Consists of utricle and saccule of the vestibule
Static labyrinth
What part of the vestibular area is anterior?
Saccule
What is predominately involved in evaluating position of head relative to gravity?
Static labyrinth
What responds to linear acceleration and deceleration (such as the change in car speed)
Static labyrinth
What maintains proper head position in response to change in linear motion (walking)?
Static labyrinth
What is involved in evaluating movements of the head?
Dynamic labyrinth
What labyrinth is associated with semicircular canals?
Dynamic labyrinth
What maintains proper head position in response to rotational movement (Turning)
Dynamic labyrinth
What epithelial tissue makes up the wall of the vestibule?
Simple cuboidal
What respond to the pull of gravity and report changes in head position?
Maculae
Maculae are located …
In equilibrium receptor regions
What has specialized 2-3 mm epithelium, consists of supporting cells and hair cells, and 1 cilium, and many microvilli?
Maculae
What gelatinous mass do the hair cells embed into?
Otolithic membrane
Crystal like structures composed of protein and CaCO3 rocks
Otoliths
What have no axons, and directly synapse with CN VIII?
Hair cells
What macula is perpendicular to the skull base?
Saccular macula
What macula is parallel to skull base?
Utricular macula
What determines the intensity of hair cell stimulation in balance?
Pattern of head movement
Info perceived by brain for balance is handled how..
Subconsciously
What is associated with semicircular canals and allows movement detection in all directions?
Dynamic equilibrium
What is the enlarged base at the bottom of semi circular Canals called and what does it hold
Ampulla, holds the equilibrium receptor
What is the equilibrium receptor called in dynamic equilibrium?
Crista ampullaris
What receptor responds to the rotational (angular) movements of the head?
Crista ampullaris
What consists of crest of epithelium and cupula, with sterocillia hair cells embedded in the cupula
Crista ampullaris
No otoliths in dynamic equilibrium means …
No gravitational pull
What is involved in evaluating movements of the head?
Dynamic equilibrium
What liquid moves the cupula to bend hair cells?
Endolymph
When semicircular canal starts to move with body…. (What way does the fluid go)
Endolymph is stationary and pushes cupula other direction
The displacement of the cupula is most intense when rate of head movement changes meaning we are…
Detecting changes in rate movements not movement alone
As movement continues the Endolymph will catch up to the cupula and this happens
Stimulation stops
When the head stops moving (dynamic labyrinth) the Endolymph moves again this time….
Displacing the cupula in the same direction the head moved
Nervous system pathway for balance receives info from …. (3 things)
- Inner ear signals
- Proprioception receptors
- Visual system
What is the sense of self movement, force and body position?
Proprioception
What process is mediated by proprioceptors in muscles, tendons and joints
Equilibrium
Signals are integrated to allow …
Body to maintain posture and balance
What part of the brain are we consciously aware of sensory input detection?
Cerebrum
APs associated with balance pathways are conducted to this place only
Vestibular area of cerebral cortex
As we age the # of _____ and # of ______ in saccule, utricle, and ampullae decrease
Hair cells and otoliths
Who are has decreased sensitivity to gravity, acceleration, and rotation?
Elderly
Old people have these symptoms that make them fall
Dizziness and vertigo
The neurons of maculae and Cristae ampullaris converge into…
Vestibular ganglion
The vestibular ganglion passes sensory info to the …. (What and where in brain)
Vestibular nucleus in the medulla (brain stem)
What influences postural muscles
Cerebellum
Vestibular nuclei axons synapse with motor nuclei of what CNs (3 cn for eye movement)
CN III, IV, VI
The vestibular nuclei in the Brian stem go where next in the brain?
Posterior ventral nucleus of the thalamus
When thalamic neurons go to vestibular areas of the cerebral cortex we have a …
Conscious awareness of balance
