Question | Answer |
What does the inner ear consist of? | The inner ear can be divided into 3 sections- vestibule, cochlea, and semicircular canals
Also consists of 2 labyrinthine systems- osseous and membranous |
Osseous Labyrinth | -A system of canals and cavities in the petrous portion of the temporal bone
-vestibule forms the central portion
-semicircular canals lie posterior to the vestibule
-cochlea lies anterior and slightly inferior to vestibule |
Vestibule | Houses 2 structures concerned with balance: utricle and saccule
*Both of these structures contain sensory epithelia that are responsive for linear acceleration and effects of gravity |
Semicircular Canal | There are 3 semicircular canals- superior, posterior, and anterior
-Semicircular canals open into vestibule via 5 openings called ampula(e)
- ampullae contain sensory receptors for rotational acceleration |
Cochlea | -Medial portion of bony labyrinth
-Cochlea is where auditory portion of the ear is housed
-Snail coiled canal (2 3/4 turns)
-Cochlea is twisted around a central core pillar of bone called the modiolous |
Cochlea | -Divided into upper and lower ducts (upper-scala vestibule and lower-scala tympani)
-the s. vestibule and s. tympani are completely separated except near the apex where a tiny opening called the helicotrema permits communication between the two |
Cochlear Duct | -attaches to the outer wall of the cochlea via the spiral ligament
-superiorly the cochlear duct is seperated from the s. vestibule by Reissner's membrane (vestibular membrane) which extends from the osseous spiral lamina to outer wall of cochlea |
Cochlear Duct | Inferiorly, the cochlear duct is separated from the s. tympani by the basilar membrane which extends from the spiral lamina to the spiral ligament on the s. tympani side |
Basilar Membrane (Cochlear Duct) | -Basilar membrane is narrower and stiffer at base, broader at apex and has 2 parts:
1. one part is thin and extends from spiral lamina to outer pillars (zona arcuta)
2. one part is thicker and extends to the spiral ligament (zona pectinata) |
Membranous Labyrinth | -contained within the osseous labyrinth and resembles its shape
-filled with endolymph
-membranous labyrinth is found in the 3 semicircular canals, vestibule, cochlea, and cochlear duct |
Osseous Spiral Lamina | |