Development of Musculoskeletal System and Skin

Question 1

What sclerotomal structure develops to allow the nerves to reach the nearby myotomes and dermatomes?

Answer 1

Von Ebner’s fissure

Question 2

What is the only mature remnant of the notochord?

Answer 2

Nucleus pulposus

Question 3

What is the last region of the vertebrae to ossify?

Answer 3

Spinous process

Question 4

Regional differences between vertebrae and ribs are influenced by the expression of what family of genes?

Answer 4

Hox genes

Question 5

Failure of inferior fusion of the sternal bars results to what sternal deformity?

Answer 5

Bifid xiphoid process

Question 6

The epimere gives rise to what muscle group?

Answer 6

Intrinsic muscles of the back

Question 7

Failure of muscle development during embryogenesis results in several sets of developmental anomalies. What muscle fails to form in Poland syndrome?

Answer 7

Pectoralis muscle

Question 8

Prune belly syndrome is a developmental anomaly that presents as a failure to form which muscle?

Answer 8

Abdominal muscles

Question 9

One of the malformations of the tail segment is fusion of rear limb buds. What is this condition called?

Answer 9

Sirenomelia

Question 10

Failure of apoptosis on interdigital tissues of the hands and feet results to what type of congenital defect?

Answer 10

Syndactyly

Question 11

The limb bone arises from which type of mesoderm?

Answer 11

Lateral plate mesoderm

Question 12

What is the first step in endochondral ossification?

Answer 12

Artery invades the middle of the cartilage

Question 13

The secondary ossification centers are found in what area of the long bones?

Answer 13

Epiphysis

Question 14

What condition is caused by a mutation of the FGFR3 protein, which results in early failure of endochondral ossification due to premature closure of the epiphyseal plates?

Answer 14

Achondroplasia

Question 15

What condition arises when there is excessive growth hormone released after the growth plates have closed?

Answer 15

Acromegaly

Question 16

With regards to outgrowth of the limb buds, which structure is on the tip of the bud and what signal is produced in it?

Answer 16

The apical epidermal ridge (AER), the signal produced is fibroblast growth factor 8 (FGF8), which interacts with mesenchyme to keep the limb growing. Implanting FGF8 into an embryo could induce the formation of additional limbs

Question 17

What is the molecular marker that signals for medio-lateral patterning? Where is it localized?

Answer 17

The protein Sonic Hedgehog (Shh)

It is localized in the medial region of the developing limb, the zone of polarizing activity (ZPA)

Question 18

What congenital anomaly arises due to disruption of limb initiation and presents with normal looking hands or feet but without the intervening long bones?

Answer 18

Phocomelia

Question 19

What anti nausea medication was previously prescribed to pregnant patients, which resulted in offspring with underdeveloped or absent limbs?

Answer 19

Thalidomide

Question 20

Which components do skin come from?

Answer 20

Both ectoderm and mesoderm

Question 21

Where do the epidermis and dermis originate from?

Answer 21

The epidermis is the outermost layer derived from ectoderm that covers the embryo

The dermis is the inner layer derived from mesoderm. The lateral plate mesoderm and dermatome of the somites contribute to the dermis in different parts of the body

Question 22

The basal later of the epidermis proliferates and creates what layer of cells that protects the growing embryo?

Answer 22

The periderm

Question 23

What is the vernix caseosa?

Answer 23

The waxy or cheese like substance found coating the skin of newborn human babies. It keeps the embryo safe from amniotic fluid

Question 25

What is the innermost layer of the mature epidermis?

Answer 25

Stratum germinatum

Question 26

Melanoblasts are derived from which embryonic origin?

Answer 26

Neural crest cells

Question 27

Failure of migration of neural crest cells may result in what condition characterized by the absence of pigment in skin, hair, and retina

Answer 27

Albinism

Question 28

Cells that create the hair itself are derived from?

Answer 28

The epidermis

Question 29

What are the 2 additional associated structures a mature hair follicle has?

Answer 29

Sebaceous glands and arrector pili muscles

Question 30

What are lanugo hair?

Answer 30

Fine coating of hair covering most of the child’s body at birth, disappears and is replaced by hair on head

Question 31

Which structure supplies blood to the growing follicle?

Answer 31

Papilla

Question 32

The nail plate is produced by which structure in the appendages?

Answer 32

Proximal nail fold

Question 33

What do the deciduous set of teeth consist of?

Answer 33

2 incisors
1 canine
2 molars

Question 34

What are they replaced by?

Answer 34

2 incisors
1 canine
2 premolars
3 molars (3rd is wisdom tooth)

Question 35

What is the site of tooth formation?

Answer 35

Dental lamina

Question 36

What is the hardest mineralized substance in the human body?

Answer 36

Enamel

Question 37

What group of cells produce mineralized enamel

Answer 37

Ameloblasts

Question 38

Dentin is produced by what group of cells?

Answer 38

Odontoblasts

Question 39

What covers the root of teeth?

Answer 39

Cementum

Question 40

What medication is noted to cause teeth staining when exposed to during teeth formation?

Answer 40

Tetracycline

Question 41

What are the contractile cells that surround sweat glands and propel sweat up the lumen and onto the surface of the skin?

Answer 41

Myoepithelial cells