Embryology: Musculoskeletal System Flashcards
The nucleus polposus is derived from which of the following?
A. Sclerotome
B. Notochord
C. Dermomyotome
D. Epimere
E. Ectoderm
A. Sclerotome
- dorsal forms vertebral arch
- ventral forms vertebral body
- lateral forms transverse process
B. Notochord
(note: anulus fibrosis from mesoderm)
C. Dermomyotome
- dermatome forms dermis of back and limbs
- myotome forms skeletal muscle precursors
D. Epimere
- dorsal rami of instrinsic back muscles
E. Ectoderm
- generally, develops into parts of the skin, the brain and the nervous system
Defective development of the epimere is most likely to affect which of the following muscles?
A. Erector spinae
B. Pronator teres
C. Rectus femoris
D. External oblique
E. Internal intercostal
A. Erector spinae
- Epimere –> instrinsic back muscles
B. Pronator teres
anterior condensation of hypomere –> upper limb: flexors and pronators
C. Rectus femoris
D. External oblique
E. Internal intercostal
Lobster claw deformity is caused by absence of the 3rd digit with frequent fusion of the thumb/index finger and the 4th/5th digits. This condition can be known by which of the following terms?
A. Phocomelia
B. Polydactyly
C. Ectrodactyly
D. Amelia
E. Micromelia
F. Meromelia
A. Phocomelia: Digits develop prematurely Proximal elements of limb absent aka flipper limb –> hands/feet without arms/thighs (associated with Thalidomide)
B. Polydactyly - additional digits due to high Shh in the ZPA; usually on ulnar side
C. Ectrodactyly - Lobster claw deformity
D. Amelia - Complete absence of a limb via loss of FGF signalling
E. Micromelia: Abnormally short segments of extremetities
F: Meromelia: Partial absence of a limb via loss of FGF signalling
Although most smooth muscle and cardiac muscle is derived from splanchnic mesoderm, the smooth muscle of the pupil is derived from:
A. Somites
B. Paraxial
C. Intermediate mesoderm
D. Neuroectoderm
E. Endoderm
D. Neuroectoderm
Which of the following bones is derived from paraxial mesoderm?
A. Parietal
B. Mandible
C. Frontal
D. Sphenoid
E. Maxilla
A. Parietal
Mandible, Frontal, Sphenoid + Sq. temporal, viserocranium, Maxilla from Neural Crest Cells
In which week do the limb buds first appear?
A. Week2
B. Week 3
C. Week 4
D. Week 5
C. Week 4
Musculoskeletal development occurs within which of the following time frames?
Between week 4 and week 8
Between week 3 and week 8
Between week 2 and week 7
Between week 3 and week 7
Between week 3 and week 8 - during embryonic period
A 24-year-old man presents to the emergency room with a stress fracture of the pars interarticularis on the 4th lumbar vertebra. What embryological cell population is this vertebra derived from?
A. Neural crest cells
B. Intermediate mesoderm
C. Lateral plate mesoderm
D. Paraxial mesoderm
keyword to question: ON LUMBAR VERTEBRA
D. Paraxial mesoderm forms ventral column + ribs, dermis of back, skeletal muscle, axial skeleton
A. Neural crest cells from Mandible, Frontal, Sphenoid + Sq. temporal, viserocranium, Maxilla
B. Intermediate mesoderm
C. Lateral plate mesoderm forms dermis of ventrolateral trunk and limbs, limb bones, sternum, appendicular skeleton
Pronator teres is primarily derived from which cell population?
Dermatome
Neural crest cells
Epimere of the myotome
Hypomere of the myotome
Lateral plate mesoderm
Dermatome
Neural crest cells
Epimere of the myotome
Hypomere of the myotome
Lateral plate mesoderm
A 31-year-old man is born with a rare congenital upper limb deformity affecting growth along the proximodistal axis is seen in the image above. Which of the following morphogens mediates normal limb patterning along this axis?
A. Sonic hedgehog
B. Bone morphogenic protein
C. Fibroblast growth factors
D. WNT7a
E. Noggin
C. Fibroblast growth factors: Development of the limb bud along the proximodistal axis
A. Sonic hedgehog: development of the limb bud along the craniocaudal axis
B. Bone morphogenic protein: controls cell death in interdigital areas
D. WNT7a: development of the limb bud along the dorsoventral axis
E. Noggin: (along w/ shh) cause the ventromedial part of somite to become mesenchyme again to form the SCLEROTOME
anterior vs posterior condensation of hypomere
(hint: upper limbs and lower limbs)
Anterior condensation forms
- Upper Limb – Flexor and Pronator muscles
- Lower Limb – Flexor and Adductor muscles
- flexors, pronators, adductors
Posterior condensations forms;
- Upper Limb – Extensor and Supinator muscles
- Lower Limb – Extensor and Abductor muscles
- extensors, supinators, abductors
