11/14/2013

11/14/2013

Answers:

With regards to embryology, Meckel's cartilage leads to formation of the --- whereas Reichert cartilage leads to formation of the---.
A) Stapes Footplate; Sphenomandibular ligament 
B) Long Process of Incus; Stapes Suprastructure
C) Body of Incus; Mandible  
D) Head of Malleus; Manubrium of Malleus

-Meckel cartilage (from 1st pharyngeal arch) = head of malleus / body of incus  mandible / sphenomandibular ligament.
-Reichert cartilage (2nd pharyngeal arch) = manubrium of malleus, long process of incus, stapes suprastructure and tympanic part of stapes footplate. Also, facial nerve,muscles of facial expression, stapedius, upper hyoid and stylohyoid ligament.

All of the muscles of facial expression are innervated on their deep side except for what three exceptions?

Buccinator, Levator Anguli and Mentalis are the three muscles not innervated on their deep side. A good mnemonic to remember this is BLAM.

MC Questions:
Which ossicle requires the longest period of development?
A) Incus 
B) Stapes 
C) Malleus 
D) They are all equal

Free Response Question:
What does a "high riding" bulb refer to?

Quick Facts:

Congenital Cholesteatomas
-Congenital cholesteatomas = middle ear cholesteatoma in presence of intact TM w/o hx of perf, OM, otorrhea or oto surgery.
-Several features distinguish congential from aquired coleasteatomas:
-Acquired often present in setting of existing ear pathology.
-Acquired mass is often symptomatic (otorrhea, otalgia, hearing loss)
-Acquired is found to be expanding in direct continuity w/TM perf or retraction pocket.
-Congenital not associated w/ oto pathology, often clinically silent and discovered incidentally.
-Congenital tend to have well aerated mastoids, unlikely acquired.
-Pathogenesis unclear
-"classically” in anterosuperior quadrant of mesotympanum (27-67%)
-Small pearls next to long process of malleus (minimal ossicular involvement/hearing loss)
-Treat w/ surgical removal.
-Recur in 30-55% of cases after surgery.