Chapter 20 - Lower Limb

Question 1

Which of the following arteries gives rise
to the axis artery of the lower limb?

(A) External iliac artery
(B) Femoral artery
(C) Profunda femoris artery
(D) Umbilical artery
(E) Inferior gluteal artery

Answer 1

D. Umbilical Artery

Early in development, the umbilical artery gives rise to the axis artery.

Question 2

The femur develops from which of the
following?

(A) Somite mesoderm
(B) Lateral plate mesoderm
(C) Intermediate mesoderm
(D) Extraembryonic mesoderm
(E) Sclerotome mesoderm

Answer 2

B. Lateral plate mesoderm

All bones of the lower limb form from lateral plate mesoderm that condenses along the
central axis of the lower limb bud.

Question 3

The rectus femoris muscle develops from
which of the following?

(A) Posterior condensation
(B) Anterior condensation
(C) Lateral plate mesoderm
(D) Extraembryonic mesoderm
(E) Sclerotome mesoderm

Answer 3

A. Posterior condensation

Somite mesoderm migrates into the limb bud and forms two condensations. The posterior
condensation of the lower limb gives rise to the extensors of the lower limb, which
attain an anterior location in the adult because of the medial rotation of 90.

Question 4

Which of the following muscles will the
posterior divisions of the lumbosacral plexus
innervate?

(A) Semitendinosus
(B) Semimembranosus
(C) Long head of biceps femoris
(D) Rectus femoris
(E) Gastrocnemius

Answer 4

D. Rectus femoris

One of the nerves that form from the posterior divisions of the lumbosacral plexus is the
femoral nerve. Posterior divisions of the lumbosacral plexus will innervate muscles derived
from the posterior condensation (extensors). Rectus femoris muscle is an extensor at the
knee joint. Note that rectus femoris muscle and the femoral nerve are related embryologically
to the posterior condensation and posterior divisions even though in the adult they are
located anterior. This occurs because of the medial rotation of 90.

Question 5

During weeks 6–8, the lower limb bud will
rotate

(A) Medially 90
(B) Laterally 90
(C) Medially 180
(D) Laterally 180
(E) No rotation occurs

Answer 5

A. Medially 90

The lower limb bud will rotate medially 90 so that the knee points anteriorly.