Temple LEA

Question 1

Embryology: At what week does the limb bud appear?

Answer 1

Week 4

Question 2

Embryology: During which week of gestation do limb buds flatten?

Answer 2

Week 5

Question 3

Embryology: At what week do the lower limb buds undergo their first rotation?

Answer 3

Week 6
In this first rotation, limbs move horizontally from the coronal to sagittal plane with soles of feet facing each other. Second rotation occurs in the following weeks.

Question 4

Embryology: During which week of gestation do the lower limbs undergo their second rotation?

Answer 4

Week 7-8
Limb buds internally rotate 90 degrees so that the knees and extensor compartment of the leg face anteriorly.

In contrast, the upper limbs externally rotate 90 degrees.

Question 5

Embryology: What is meant by by “pre-axial” and “post-axial”?

Answer 5

Pre-axial: developmentally ventral muscles or the anterior condensation of mesoderm. Innervated by anterior divisions of ventral rami.

Post-axial: developmentally dorsal muscles or the posterior condensation of mesoderm. Innervated by posterior divisions of ventral rami.

Question 6

Embryology: What two embryological tissues make up the limbs? What do they each give rise to?

Answer 6

Mesoderm: gives rise to bones, ligaments, tendon and dermis.

Ectoderm: gives rise to nerves, epidermis, nails, hair, and apical ectodermal ridge

Question 7

Embryology: Failure of apoptosis between toe rays during limb bud development leads to what congenital condition?

Answer 7

Syndactyly

Question 8

Embryology: By week 8 of gestation, the foot is in what position?

Answer 8

Plantarflexed and adducted (or the equines-supinated position)

Question 9

Embryology: All bones of the lower limb form from ______ precursors.

Answer 9

Cartilaginous

This process is known as endochondral ossification.

Question 10

Embryology: What are the developmentally ventral muscle compartments of the hip and thigh?

Answer 10

Posterior and medial muscle compartments.
(hamstrings and aDductors)
Remember: vEntral = prE-axial

Question 11

Embryology: What are the developmentally dorsal muscle compartments of the hip and thigh?

Answer 11

Anterior and lateral muscle compartments.
(quadriceps and aBductors)
Remember: dOrsal = pOst-axial

Question 12

Embryology: What are the developmentally ventral muscle compartments of the leg and foot?

Answer 12

Posterior (superficial and deep) muscle compartments of the leg.

Plantar intrinsic muscles of the foot.

Question 13

Embryology: What are the developmentally dorsal muscle compartments of the leg and foot?

Answer 13

Anterior and lateral muscle compartments of the leg.

Dorsal intrinsic muscles of the foot.

Question 14

Embryology: Pre-axial muscles are innervated by which divisions of ventral rami?

Answer 14

Anterior division

Question 15

Embryology: Post-axial muscles are inverted by which division of ventral rami?

Answer 15

Posterior division

Question 16

Embryology: Hip and thigh muscles that are developmentally ventral rise from what two skeletal landmarks?

Answer 16

Ischium and Pubis

Question 17

Embryology: name the anterior divisions of the lumbar and sacral plexuses.

Answer 17

Lumbar: obturator n., accessory obturator n.

Sacral: tibial n., N. to quadratus femoris, N. to obturator internus, pudendal n, posterior femoral cutaneous n.

These nerves innervate pre-axial muscle groups.

Question 18

Embryology: Hip and thigh muscles that are developmentally dorsal arise from what two skeletal landmarks?

Answer 18

Vertebral column and Ilium

Question 19

Embryology: Name the posterior division of the lumbar and sacral plexuses.

Answer 19

Lumbar: lateral femoral cutaneous n., femoral n.

Sacral: superior gluteal n., inferior gluteal n., common perineal n., posterior femoral cutaneous n.

These nerves innervate post-axial muscle groups.

Question 20

Embryology: What muscles, due to their innervations, have both developmentally ventral and dorsal components?

Answer 20

Biceps femoris: long head (tibial n.); short head (common peroneal n.)

Pectineus: femoral n. and obturator n.

Question 21

Embryology: A club foot deformity, seen in about 1/1000 births, is characterized by a foot in what position related to the three cardinal planes?

Answer 21

1. Plantarflexed/equinus (sagittal)
2. Adducted (transverse plane)
3. Inverted/varus (frontal plane)