10/7/2013

10/7/2013

Answers:

The 1st branchial arch is the origin of--- whereas the 2nd branchial arch is the origin of---.
A) Head of Malleus; Stapes Footplate 
B)Stapes superstructure; long process of incus 
C)Short process of incus; Body of Malleus 
D)Head of the malleus; long process of malleus 
E) Stapes footplate; long process of incus

Embryologic origin of middle ear is complex:
-1st branchial arch = head of malleus and body/short process of incus
-2nd branchial arch = long process of malleus, long process of incus and stapes superstructure.
-otic capsule = stapes footplate

Name all five subsections of the middle ear cavity.

Mesotympanum, hypotympanum, protympanum, retrotympanum and attic

MC Questions:
Perilymph is rich in ---, Endolymph is rich in---.
A)Na, Cl 
B)Na, K 
C) Cl, Na 
D) Cl, K 
E) K, Na 
F) K, Cl

Free Response Question:
Name the three nerves that branch off the facial nerve in the temporal bone.

Quick Facts:
Passive Mechanics Within the Cochlea
-Tectorial membrane lies on top of organ of corti.
-Sound causes vibration of corti up and down. 
-Basilar membrane fixed to osseous spiral lamina
-Tectorial membrane fixed at different position.
-Movement causes shearing force.
-Base of cochlea = high frequency = lower mass, high stiffness
-Apex of cochlea = low frequency = higher mass, lower stiffness.