Embryology of the Lower Limb Quiz
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Questions and Answers

During which weeks of development do the upper and lower limb buds become visible as outpocketings from the ventrolateral body wall?

  • Weeks 5-8 (correct)
  • Weeks 9-12
  • Weeks 4-5
  • Weeks 1-4

    • At what level does the upper limb bud appear during development?

  • T3-T6
  • T7-T10
  • C1-C3
  • C4-T2 (correct)

    • At what level does the lower limb bud appear, in relation to vertebral levels?

  • L2-S2 (correct)
  • S6-Co1
  • L1-L3
  • S3-S5

    • What is the purpose of studying the timing, position, and pattern of formation of the limb buds?

    <p>To understand the adult pattern of anatomy</p> Signup and view all the answers

    What developmental events occur at the end of the fourth week of development?

    <p>Formation of limb buds</p> Signup and view all the answers

    What factors influence the pattern of innervation of the limbs?

    <p>Position and pattern of formation of the limb buds</p> Signup and view all the answers

    What is the main cause of split foot?

    <p>Excessive programmed cell death in the interdigital spaces</p> Signup and view all the answers

    During which weeks of development is the most sensitive period for teratogen-induced limb malformations?

    <p>Fourth and fifth weeks</p> Signup and view all the answers

    Which gene initiates the development of forelimbs?

    <p>Tbx5</p> Signup and view all the answers

    What is essential for limb bud development in the proximal to distal axis?

    <p>Apical Ectodermal Ridge (AER)</p> Signup and view all the answers

    Which gene regulates the anteroposterior axis of limb development?

    <p>Sonic Hedgehog (SHH)</p> Signup and view all the answers

    What controls the dorsoventral axis in limb development?

    <p>HOX genes</p> Signup and view all the answers

    What does the limb bud consist of?

    <p>Core of mesenchyme derived from somatopleuric lateral plate mesoderm and ventrolateral cells of the somites</p> Signup and view all the answers

    What creates the progress zone in the mesoderm during limb development?

    <p>Fibroblast Growth Factors (FGFs)</p> Signup and view all the answers

    What happens as the limb grows in relation to Zone of Polarizing Activity (ZPA)?

    <p>ZPA moves distally away from AER</p> Signup and view all the answers

    What genes regulate bone patterning, muscle pattern, joint orientation, and epidermal differentiation in limb development?

    <p>HOX genes</p> Signup and view all the answers

    What is the main function of the Apical Ectodermal Ridge (AER) in limb bud development?

    <p>To promote cell proliferation and prevent differentiation</p> Signup and view all the answers

    What regulates the differentiation of the extensor and flexor compartments in limb development?

    <p>HOX gene expression</p> Signup and view all the answers

    What causes the proper order and pattern of digits in limb development?

    <p>Misexpression of ZPA or SHH in the anterior margin of a limb</p> Signup and view all the answers

    Which gene initiates the development of forelimbs?

    <p>Tbx5</p> Signup and view all the answers

    What is responsible for regulating the anteroposterior (craniocaudal) axis in limb development?

    <p>Zone of polarizing activity (ZPA)</p> Signup and view all the answers

    What is the role of FGFs (fibroblast growth factors) in limb bud development?

    <p>Creating the progress zone in the adjacent mesoderm</p> Signup and view all the answers

    Which part of the limb bud receives branches from C5-T1 Nerves?

    <p>Upper Limb buds</p> Signup and view all the answers

    What causes webbed digits in limb development?

    <p>Inhibition of BMPs</p> Signup and view all the answers

    What causes mirror image duplication of limb structures (polydactyly)?

    <p>Misexpression of SHH in the anterior margin of a limb</p> Signup and view all the answers

    What stimulates cell proliferation and prevents differentiation during limb bud development?

    <p>FGFs secreted by the AER</p> Signup and view all the answers

    Which genetic factor controls both digit number and digit pattern in limb development?

    <p>SHH secreted by ZAP</p> Signup and view all the answers

    What causes syndactyly in limb development?

    <p>Misexpression of SHH in the anterior margin of a limb</p> Signup and view all the answers

    During limb development, what process leads to the removal of interdigital tissue to create separate digits?

    <p>Apoptosis</p> Signup and view all the answers

    Which molecule appears to be the inductive signal for positioning of joints during limb development?

    <p>WNT14</p> Signup and view all the answers

    What is the main source of limb musculature during limb development?

    <p>Myotomes of the somite</p> Signup and view all the answers

    What leads to the formation of a joint cavity during limb development?

    <p>Cell death</p> Signup and view all the answers

    Which nerve supply is responsible for the upper limb buds during limb development?

    <p>C5-T1 Nerves</p> Signup and view all the answers

    Which statement best describes the rotation of limbs during development?

    <p>Upper limb rotates 90o laterally, whereas the lower limb rotates 90o medially.</p> Signup and view all the answers

    Which teratogen was used as a sedative and antinauseant in the 1960s and caused interruption of AER function and proximodistal limb growth?

    <p>Thalidomide</p> Signup and view all the answers

    Which developmental defect is characterized by absence of all digits on a limb?

    <p>Adactyly</p> Signup and view all the answers

    What causes polydactyly during limb development?

    <p>'Too many parts of the AER'</p> Signup and view all the answers

    What leads to brachydactyly during limb development?

    <p>Disruption of AER function</p> Signup and view all the answers

    What causes split foot during limb development?

    <p>Excessive programmed cell death in interdigital spaces</p> Signup and view all the answers

    What was the period of vulnerability for teratogen-induced limb malformations?

    <p>5th-8th week</p> Signup and view all the answers

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