10/4/2013

10/4/2013

Answers:

A common starting point for cholesteatoma is...
A) Shrapnell membrane 
B) Pars Tensa 
C) EAC 
D) Eustachian tube 
E) None of the above

Shrapnell membrane aka Pars Flaccida is superior to the anterior and posterior malleal folds and is a common place where cholesteatomas start.

Describe the "tragal pointer"

The "tragal pointer" refers to the fact that the facial nerve is often found 1cm deep and 1cm inferior to the tragus.

MC Questions:
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

Free Response Question:
Name all five subsections of the middle ear cavity.

Quick Facts:
Inner Ear Fluid Compartments
-2 fluid filled chambers:    
-Outer = perilymph = sodium rich (similar to CSF)    
-Inner = endolymph = potassium rich (similar to intracellular fluid)
-Marginal cells in stria vascularis pump K+ to make differential.
-This electrochemical gradient provides energy to power sensory cells.
-System is unique in that sensory cells rely on other cells to provide energy.