Chapter 8

Question 1

The cochlear duct contains the spiral organ
of Corti and is derived from which of the following?
(A) Both ectoderm and mesoderm
(B) Neural crest
(C) Endoderm
(D) Mesoderm
(E) Ectoderm

Answer 1

E. The cochlear duct is derived from a thickening of the surface ectoderm called the otic placode.

Question 2

The middle ear cavity
(A) is of mesodermal origin
(B) develops from pharyngeal pouch 1
(C) develops from pharyngeal arch 1
(D) develops from pharyngeal arch 2
(E) develops from the otic vesicle

Answer 2

B. The middle ear cavity develops from pharyngeal pouch 1 as it evaginates to form the tubotympanic
recess.

Question 3

The tubotympanic recess gives rise to
(A) a conduit that interconnects the middle
ear and the nasopharynx
(B) the external auditory meatus
(C) the internal auditory meatus
(D) the facial canal
(E) a conduit that interconnects the perilymphatic
space with the subarachnoid space

Answer 3

A. The tubotympanic recess is derived from pharyngeal pouch 1. It gives rise to the tympanic
cavity and the auditory (eustachian) tube; the auditory tube interconnects the tympanic cavity
with the nasopharynx.