BIOL 4380 Lecture Notes - Lecture 9: Bony Labyrinth, Vestibulocochlear Nerve, Semicircular Canals
13 May 2018
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March 1st
• Chapters for the midterm: 9, 11, 13, 14 and 15.
• Vestiular sste → allos to fous our gaze oto soethig, ee ith oig our head.
Also it helps us be able to move our heads without snapping our neck! It also helps us protect
ourseles if e’re fallig. Whe fallig, lis ill e positioed i a a as to protet our od.
• A lot of terminology you will have to know for midterm 2!
• Vestibular system is very closely linked to our auditory system. The structure contiguous with
ohlea sharig its edolph, is alled the estiular larith it’s a sa of iteroeted
chambers), the labyrinth and the cochlea have the same embryonic origin. The labyrinth uses
hair cells sensing the motion, very similar to the hair cells in the cochlea.
• Translational and rotational movement of the head,
o Translational movement: when the head moves back and forth or left and right.
o Rotational movement: your head rotating or your body moving.
• Labyrinth is fairly deeply hidden inside the temporal bone of the skull. There are 2 otolith
organs: utricle and saccule. These are sacs filled with endolymph. They are connected by 3
semicircular canals (superior, posterior and horizontal). Why are there 3 of them? To sense
motions in the 3 dimensional space, along 3 axes.
• There are 3 structures where the canals meet the otolith, called the ampullae. Both the otolith
and ampullae have hair cells in them.
• The canal that connects cochlea to labyrinth are called canal reuniens.
• The nerve fibers that innervate both the cochlea and the labyrinth come largely through the
raial ere VIII → splits ito the auditor part ieratig ohlea ad estiular part
(innervating the labyrinth). Ignore facial nerve.
• All structures are filled with endolymph.
• The canals largely detect rotations and the otolith organs detect translations of your head.
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Document Summary
Chapters for the midterm: 9, 11, 13, 14 and 15: vesti(cid:271)ular s(cid:455)ste(cid:373) allo(cid:449)s to fo(cid:272)us (cid:455)our gaze o(cid:374)to so(cid:373)ethi(cid:374)g, e(cid:448)e(cid:374) (cid:449)ith (cid:373)o(cid:448)i(cid:374)g (cid:455)our head. Also it helps us be able to move our heads without snapping our neck! The structure contiguous with (cid:272)o(cid:272)hlea (cid:894)shari(cid:374)g its e(cid:374)dol(cid:455)(cid:373)ph(cid:895), is (cid:272)alled the (cid:448)esti(cid:271)ular la(cid:271)(cid:455)ri(cid:374)th (cid:894)it"s a sa(cid:272) of i(cid:374)ter(cid:272)o(cid:374)(cid:374)e(cid:272)ted chambers), the labyrinth and the cochlea have the same embryonic origin. Labyrinth is fairly deeply hidden inside the temporal bone of the skull. There are 2 otolith organs: utricle and saccule. They are connected by 3 semicircular canals (superior, posterior and horizontal). To sense motions in the 3 dimensional space, along 3 axes: there are 3 structures where the canals meet the otolith, called the ampullae. Ignore facial nerve: all structures are filled with endolymph, the canals largely detect rotations and the otolith organs detect translations of your head. In the exam, he might give a schematic figure for you to write the terminology.
