Deck 14: Limbs

Question 1

________ Exerts an inductive influence

A)Upper limb
B)Apical ectodermal ridge
C)Somites
D)Meromelia
E)Lower limb

Answer 1

B
The apical ectodermal ridge (AER)is a thickened,epithelial plaque at the distal end of each limb bud.The AER exerts an inductive influence on the limb mesenchyme that initiates growth and development of the limbs.There is no further elaboration of distal structures (hands and fingers)if the ridge is removed experimentally.

Question 2

________ Absence of the limbs

A)Dermatome
B)Phocomelia
C)Digital rays
D)End of fourth week
E)Amelia

Answer 2

E
Amelia refers to absence of a limb(s).This condition resulted when thalidomide was ingested by pregnant women early in the fourth week after fertilization.

Question 3

________ Type of meromelia

A)Dermatome
B)Phocomelia
C)Digital rays
D)End of fourth week
E)Amelia

Answer 3

B
Phocomelia is a type of meromelia (partial absence of the limbs).In this type of meromelia,the limbs have a flipper-like appearance.The term "phocomelia" is not commonly used;meromelia is the preferred term for all defects involving partial absence of a limb(s).

Question 4

________ Rotates medially

A)Upper limb
B)Apical ectodermal ridge
C)Somites
D)Meromelia
E)Lower limb

Question 5

________ Rotates laterally

A)Upper limb
B)Apical ectodermal ridge
C)Somites
D)Meromelia
E)Lower limb

Question 6

________ Area of skin supplied by a spinal nerve

A)Dermatome
B)Phocomelia
C)Digital rays
D)End of fourth week
E)Amelia

Question 7

________ Partial absence of a limb

A)Upper limb
B)Apical ectodermal ridge
C)Somites
D)Meromelia
E)Lower limb

Question 8

________ Lower limb bud

A)Dermatome
B)Phocomelia
C)Digital rays
D)End of fourth week
E)Amelia

Question 9

________ Limb muscles

A)Upper limb
B)Apical ectodermal ridge
C)Somites
D)Meromelia
E)Lower limb

Question 10

________ Condensations of mesenchyme

A)Dermatome
B)Phocomelia
C)Digital rays
D)End of fourth week
E)Amelia