MSK 35 - Development of the Upper and Lower Limb

Question 1

When and where do the upper and lower limb buds appear?

Answer 1

Question 2

What does a limb bud consist of and what causes it to form?

Answer 2

• A limb bud consists of a mesenchymal core (derived from the somatic layer of lateral plate mesoderm) covered by ectoderm
• Localized expression of homeobox (HOX) genes activates mesenchymal cells in the lateral mesoderm causing an apical ectodermal ridge (AER) to form. This is the start off the process of limb development.
• Mesenchyme will continue to condense and give rise to the skeleton & connective tissue.

Question 3

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Question 5

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Question 6

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Question 7

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Question 8

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Question 9

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Question 10

Facts to know about the apical ectodermal ridge (AER)

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Question 11

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Question 12

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Question 13

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Question 14

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Question 15

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Question 16

When do the hand and goot plates begin to develop?

Answer 16

Week 5

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Question 18

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Question 19

What major limb developments occur in weeks 6 & 7?

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Question 20

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Question 21

What major limb developments occur in week 8?

Answer 21

Separation of the fingers and toes

Question 22

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Question 23

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Question 24

Describe the positional changes of developing limbs.

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Question 25

Describe how the upper and lower limbs rotate medially/laterally.

Answer 25

Question 26

List the major milestones in the development of the cartilaginous bones of the upper and lower limbs.

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Question 28

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Question 29

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Question 30

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Question 31

Describe how limb musculature develops.

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Question 32

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Question 33

How and when do motor and sensory axons develop and enter the limb buds?

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Question 34

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Question 35

What is the precursor of a schwann cell? Where are schwann cells found and what do they form?

Answer 35

Question 36

Facts to know abou the development of limb arteries.

Answer 36

Question 37

Facts to know about syndactyly.

Answer 37

Question 38

Facts to know about polydactyly

Answer 38

Question 39

Facts to know about congenital talipes

Answer 39

Question 40

Facts to know about amelia and meromelia.

Answer 40

Question 41

Facts to know about ectrodactyly

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Question 42

Facts to know about amniotic band syndrome.

Answer 42

Question 43

Facts to know about VACTERL syndrome

Answer 43