Question 1

Which embryonic structure is primarily responsible for inducing the proliferation of mesenchymal cells in the limb bud, leading to proximodistal limb outgrowth?

Accepted Answer

Apical Ectodermal Ridge (AER)

Question 2

A newborn presents with webbing between the fingers, but the bones are not fused. Which term best describes this condition?

Accepted Answer

Cutaneous syndactyly

Question 3

During limb development, the upper limb buds appear before the lower limb buds. If the upper limb buds appear at day 26-27, when do the lower limb buds typically appear?

Accepted Answer

Day 28-29

Question 4

Which of the following best describes the fate of the sclerotome derived from somites?

Accepted Answer

Forms the axial skeleton, including vertebrae and part of the skull

Question 5

A teratogen disrupts the function of the Zone of Polarizing Activity (ZPA) during limb development. Which of the following abnormalities is most likely to result?

Accepted Answer

Abnormal anterior-posterior patterning of the limb (e.g., mirror-image digits)

Question 6

Which process is responsible for the separation of individual digits during limb development?

Accepted Answer

Apoptosis of mesenchyme between digital rays

Question 7

A child is born with a complete absence of one upper limb. Which term best describes this condition?

Accepted Answer

Amelia

Question 8

Which of the following statements about limb rotation during development is correct?

Accepted Answer

Upper limbs rotate laterally, lower limbs rotate medially

Question 9

The primary ossification centers in long bones begin to form at which week of development?

Accepted Answer

Week 8

Question 10

Which embryonic tissue gives rise to the bones, ligaments, and blood vessels of the limbs?

Accepted Answer

Lateral plate mesoderm

Question 11

A mutation affects the migration of hypaxial myotome cells during limb development. Which of the following is the most likely consequence?

Accepted Answer

Deficiency of limb musculature

Question 12

Which of the following best describes the sequence of events in endochondral ossification of limb bones?

Accepted Answer

Mesenchymal condensation → chondrification → ossification

Question 13

Which artery is the primary axial vessel in the developing upper limb and later gives rise to the brachial artery?

Accepted Answer

Primary axial artery

Question 14

A newborn is diagnosed with clubfoot. Which of the following best describes this condition?

Accepted Answer

Abnormal position of the talus

Question 15

Which of the following is TRUE regarding the timing of limb development?

Accepted Answer

Upper limb buds appear around day 26-27, lower limb buds about 2 days later

Question 16

Which of the following best explains why thalidomide exposure during the fourth week of embryonic development can cause severe limb abnormalities?

Accepted Answer

It interferes with limb bud formation during the most sensitive period

Question 17

Which of the following best describes the role of the epiphyseal plate in long bone growth?

Accepted Answer

It allows for longitudinal growth of the bone until adulthood

Question 18

A child is born with extra fingers on both hands. Which term best describes this condition?

Accepted Answer

Polydactyly

Question 19

Which of the following statements about the innervation of limb muscles is correct?

Accepted Answer

Hypaxial muscles are innervated by ventral rami of spinal nerves

Question 20

Which of the following best describes the embryological origin of the appendicular skeleton?

Accepted Answer

Parietal (somatic) layer of lateral plate mesoderm

Limb Development: Embryology, Anatomy, and Clinical Correlations

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