OS III, EX II, Vestibular system Flashcards
Where is the vestibular system located?
Within the petrous portin of the temporal bone
what structures make up the vestibular system?
the bony labrynth and the membranous labyrinth
What is the bony labrynth subdevided into?
vestibule and semiciruclar canals
What is the membranous labrynth?
tube containing receptors for head movement
What is membranous labrynth subdivided into?
semicircular ducts and the saccule and uricle which are in the vestibule
What secretes endolymph?
cochlear ducts
how does endolymph drain?
into the dural sinuses via endolymphatic duct
What secretes perilymph?
periosteum
Where and how does perilymph drain?
drains into VCF via the perilymphatic duct
So were does both the perilymph and endolymph end up?
the sinuses, because CSF will resob into sinuses
What is meniere’s disease?
Transient vertigo and dissiness, nausea, eyemovements ets causes by excess endolymph secretion and fluid pressure
What are the three semicircular ducts?
Located in the temporal boneanterior, horizontal and posterior
How are the semicircular ducts arranged?
mutually perpendicular
How are the ducts named?
anterior is closer to face, horizontal is on bottom to side and post is pointing more to the back.
What are crista?
receptors
Where are the crista?
ampulla of each semiciruclar canal
what makes up the gelatinous mass?
epithelium of receptor hairs and supporting cells
What do the hair cells have?
single kinocilium (tallest hair bith something on top) and stereocilia that are projecting into the gelationus mass
what motions are the hair cells most sensitive to?
angular acceleration
when head turns, what happens to endolymph?:
its stays in place due to inertia causing a friciton
what convesy the net direction of head movements?
vestibbular activity, current through each loop
what would trigger an action potiential in vestibular nerve?
hair cells.
What is the macula?
Part of the receptor system, similar to the christa but with more hairs and otolith layer on top
what is an otoliths?
calcium barbonate stones embedded in a gelatinous layer
What are the two cilia types on hair cells?
Kinocilium and steriocilia
What are the layers of the macula?
neurons into macular hair cells, cilia into gel, otoliths on gel
How are the maculas of the utricle and saccule oriented?
at right angles to each other, Macula-verticle, Uricle - horizontal