Chapter 14 Limbs

Chapter 14  Limbs

Complete Chapter Questions And Answers
 

Sample Questions

MULTIPLE CHOICE

Directions: Each group of questions below consists of a numbered list of descriptive words or phrases accompanied by a diagram with certain parts indicated by letters or by a list of lettered headings. For each numbered word or phrase, select the lettered part or heading that matches it correctly, and then insert the letter in the space to the right of the appropriate number. Sometimes more than one numbered word or phrase may be correctly matched to the same lettered part or heading.

1. ________ Partial absence of a limb
a.
Upper limb
b.
Apical ectodermal ridge
c.
Somites
d.
Meromelia
e.
Lower limb

ANS: D
Meromelia (from Greek meros, part, and melos, extremity) is the term now used to classify all limb defects that involve partial absence of a limb or limbs—including hemimelia (absence of all or part of the distal half of a limb) and phocomelia (absence of the proximal part of a limb or limbs).

2. ________ Limb muscles
a.
Upper limb
b.
Apical ectodermal ridge
c.
Somites
d.
Meromelia
e.
Lower limb

ANS: C
The limb muscles develop from mesenchyme that is derived from mesenchyme in the myotome regions of the somites. Following mesenchymal-epithelial transformation, the muscle-forming cells—myoblasts—migrate into the primordia of the limbs.

3. ________ Rotates medially
a.
Upper limb
b.
Apical ectodermal ridge
c.
Somites
d.
Meromelia
e.
Lower limb

ANS: E
The developing lower limbs rotate medially through almost 90 degrees. As a result, the knees face anterolaterally.

4. ________ Rotates laterally
a.
Upper limb
b.
Apical ectodermal ridge
c.
Somites
d.
Meromelia
e.
Lower limb

ANS: A
The developing upper limbs rotate laterally through 90 degrees on their longitudinal axes; as a result, the elbows face dorsally or posteriorly in an embryo at the end of the eighth week.