Embryo

Question 1

Derivation of skeletal system? (3)

Answer 1

Paraxial and lateral plate (parietal layer) mesoderm and neural crest

Question 2

Derivations of somitomeres in head region and somites from occipital region caudally?

Answer 2

Paraxial mesoderm

Question 3

Derivation of mesenchyme which can eventually differentiate into fibroblasts, chondroblasts or osteoblasts

Answer 3

Sclerotome

Question 4

What type of bone formation is utilized via mesenchyme within pre-existing membrane? (flat bones of skull, mandible, clavicle)

Answer 4

Intramembranous ossification

Question 5

What type of bone formation is utilized via mesenchyme that condenses and forms a cartilaginous model which is replaced by bony tissues? (Most long bones)

Answer 5

Intracartilagenous/endochondral ossification

Can result in skeletal dysplasia

Question 6

Derivation of skeleton of the face? Which pharyngeal arch?

Answer 6

Viscerocranium (via mesenchyme via neural crest)

1st and 2nd pharyngeal arch

Question 7

Derivation of protective case around the brain?

Answer 7

Neurocranium (via mesenchyme)

Question 8

The roof (flat bones) of the neurocranium develops via what type of ossification?

Answer 8

Intramembranous

Question 9

The base (basilar part of occipital bone, sphenoid, ethmoid, petrous and mastoid bones) develop via what type of ossification?

Answer 9

Intracartilagenous ossification; endochondral ossification

Question 10

Derivation of membranous neurocranium?

Answer 10

Neural crest cells (anterior to pituitary fossa)

Paraxial mesoderm (posterior to pituitary fossa)

Question 11

Derivative of hypodermic and dermis?

Answer 11

Dermatome via somites via somitomeres via paraxial mesoderm

Question 12

Derivative of epicure and hypomere?

Answer 12

Myotome via paraxial mesoderm

Question 13

Derivative of centrum/body of vertebrae, vertebral arch, costal element and transverse process?

Answer 13

Sclerotome via sclerotome via somites via somitomeres via paraxial mesoderm

Question 14

Derivative of vertebral body?

Answer 14

Caudal half and cranial half of mesenchymal cells of the sclerotome

Question 15

Chordoma is either a benign or malignant tumor that arises from remnants of what structure?

Answer 15

Notochord

Most lie in base of skull, extending into nasopharynx, and can occur in lumbosacral region

Question 16

Derivative of the bony portion of ribs?

Answer 16

Sclerotome cells that remain in paraxial mesoderm

Question 17

Derivative of costal cartilages of ribs?

Answer 17

Sclerotome cells that migrate across lateral somatic frontier into adjacent lateral plate mesoderm

Question 18

Derivative of sternum?

Answer 18

Parietal layer of lateral plate mesoderm which fuse at midline forming the cartilaginous model of manubrium

Question 19

Derivative of skeletal muscle?

Answer 19

Myotome via paraxial mesoderm

Question 20

Derivative of smooth muscle?

Answer 20

Splanchnic mesoderm surrounding the gut tube

Question 21

Derivative of cardiac muscle?

Answer 21

Splanchnic mesoderm surrounding the heart tube

Question 22

Derivative of extensor muscles of vertebral column of trunk musculature

Answer 22

Epimere of the Myotomes of the trunk region

Question 23

Derivative of antero-lateral muscles of body wall and limbs of the trunk musculature?

Answer 23

Hypomere of the myotomes of trunk region