Embryology

Question 1

What begins embryological genesis of the limbs?

Answer 1

Activation of mesenchymal cells in somatic lateral mesoderm

Question 2

What genes code for limbs?

Answer 2

HOX genes

Question 3

How do limb buds elongate?

Answer 3

Proliferation of mesenchyme

Question 4

What happens at the apex of limb buds?

Answer 4

Ectoderm thickens to form an apical ectodermal ridge

Question 5

What is the apical ectodermal ridge (AER)?

Answer 5

Differentiates into blood vessels, cartilate/bone models

Question 6

Apoptosis for interdigital regions is mediated by what?

Answer 6

Bone morphogenic proteins

Question 7

What type of ossification takes place in limb bones?

Answer 7

Endochondral

all EXCEPT clavicle

Question 8

How do upper limbs rotate?

Answer 8

90o laterally so extensors are on lateral surfaces

Question 9

How do lower limbs rotate?

Answer 9

90o medially so extensors are on anterior surfaces

Question 10

What is syndactyly?

Answer 10

Webbing (either skin or bone fusion)

Question 11

What are the causes of developmental dysplasia of the hip?

Answer 11

Abnormal development of acetabulum

Generalised joint laxity

Question 12

Abnormal development of acetabulum is commonly associated with what?

Answer 12

Congenital dislocation of hip

Common after breech deliveries

Question 13

Where is syndactyly most common/

Answer 13

Foot > hand