Development of the Nervous and Musculoskeletal Systems for Limb Formation 2 Flashcards Preview

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Flashcards in Development of the Nervous and Musculoskeletal Systems for Limb Formation 2 Deck (77)
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1
Q

The sternum and appendicular skeleton, including the shoulder and pelvic girdles and limbs, arise from

A

Somatic mesoderm

2
Q

Projects from the anterolateral body wall and contains mesenchyme originating from somatic mesoderm and myoblasts originating from somitic

A

Limb bud

3
Q

The mesenchyme (somatic mesoderm) and myoblasts (somitic mesoderm) of the limb bud will differentiate to form

A

Connective tissues and skeletal muscles of limb respectively

4
Q

The chick embryo skull shows an unstained mesenchyme membrane that will soon undergo
intramembranous ossification to form

A

Flat bones of the skull

5
Q

Ossification continues after birth and ossification centers are completed at specific ages with varying rates between

A

Male and female

6
Q

Mesenchymal cells of the somitic dermatome and somatic mesoderm invade tissues deep to the surface ectoderm to form the

A

Dermis

7
Q

Forms the epidermis and epidermal derivatives like hair, nails, and sweat glands

A

Surface ectoderm

8
Q

Form the mesenchyme that differentiates into dermis connective tissue in the face and neck

A

Neural crest cells

9
Q

With the exception of some smooth muscle, skeletal, smooth, and cardiac muscle are all formed from the

A

Mesoderm

10
Q

In the MSK system, skeletal muscle is derived from

A

Paraxial mesoderm (which differentiates into somites and then myotomes)

11
Q

Myotomes contain cells that either remain in the somite region or migrate to the somatic mesoderm. These precursor muscle cells are called

A

Myoblasts

12
Q

Forms from the migration of somitic mesoderm cells into the somatic mesoderm

A

Skeletal muscle

13
Q

Myoblasts that do not migrate form the

A

Primaxial skeletal muscles of the back

14
Q

Include rhomboids, levator scapulae, latissimus dorsi, intercostals, and shoulder girdle muscles

A

Primaxial muscles

15
Q

Myoblasts that migrate to the somatic mesoderm form

A

Abaxial muscles of anterolateral body wall and limbs

16
Q

To form the large, cylindrical, multinucleate muscle fibers/cells seen in skeletal muscle, myoblasts fuse to form a

A

Syncytium

17
Q

Lie adjacent to skeletal muscle fibers and serve as stem cells to offer limited capacity for regeneration of damages skeletal muscle tissue

A

Satellite cells

18
Q

Nerves and muscle cells arise from the same level

adjacent to the

A

Neural tube

19
Q

A defect characterized by absence of the pectoralis muscles

A

Poland’s sequence

20
Q

Can present clinically with a flattened pectoral region, a missing anterior axillary fold, and a displaced nipple

A

Poland’s sequence

21
Q

Curves the embryo into a C-shape, with the embryo curving out towards the dorsal side

A

Cephalo/cranial-caudal folding of the embryo

22
Q

The process where the edges of the flat embryo bend and fuse ventrally in the midline to form a cylindrically shaped embryo

A

Lateral folding

23
Q

In lateral folding, the embryo is now a tube with two internal tubes, which are the

A

Gut tube and neural tube

24
Q

The epidermis and underlying tissues along

the anterior body wall are derived from the ventral folding and fusion of

A

Ectoderm and parietal mesoderm

25
Q

Also with folding of the lateral edges, the endoderm

fuses and creates the

A

Gut tube

26
Q

The gut tube is surrounded by the

-lies between the lateral plate mesoderm layers with parietal and visceral mesoderm

A

Intraembryonic coelom (body cavity)

27
Q

Defects can arise when the ventral body wall of the thorax, abdomen, or pelvis fail to

A

Fuse

28
Q

Incomplete fusion in the thorax can lead to

A

Ectopia cordis (heart on the outside), gastroschisis (abdominal viscera on outside), and bladder extrophy (bladder on outside)

29
Q

Limb buds project from the anterolateral body wall by the end of

A

Week 4 of development

30
Q

Made up of a core of somatic mesoderm derived

mesenchyme covered by ectoderm

A

Limb buds

31
Q

The upper limb appears first, at day 24, followed by the hind limb at

A

Day 28

32
Q

Occurs between the fifth and eighth weeks and

involves growth, induction, apoptosis, and patterning, as described below

A

Differentiation of the limb buds

33
Q

Surface ectoderm cells overlying the distal border of

the limb thickens into an

A

Apical ectodermal ridge (AER)

34
Q

Acts as a signaling center that induces nearby mesenchyme (through FGF secretion) to proliferate rapidly without differentiating to maintain distal outgrowth of limb mesenchyme

A

The AER

35
Q

The area of mesenchyme proliferation and elongation is called the

A

Progress zone

36
Q

As the limb elongates, the AER moves distally. This distal movement allows the proximal portions of the limb to

A

Differentiate and develop into cartilage and bone

37
Q

As the limb grows, cells near the proximal end are exposed to retinoic acid that causes them to differentiate into

A

Proximal bones

38
Q

Digits begin formation at the DISTAL end when apoptosis occurs in the

A

AER

39
Q

Final separation by apoptosis occurs between the webbing or rays in the interdigital spaces to form

A

Digits

40
Q

The fusion of two or more digits that may result from incomplete apoptosis between digits

A

Syndactyly

41
Q

Responsible for the differences in the structure of digits so that there is a “pinky side” and a “thumb side”

A

Zone of polarizing activity (ZPA)

42
Q

Communicates with the ZPA, which is a cluster of mesenchymal cells that secrete SHH to induce differentiation of anterior-posterior patterning of digits

A

The AER

43
Q

Dorsalizing factors that interact with ventralizing factors (such as engrailed-1) to establish the dorso-ventral axis of the limb

A

WNT7 and LMX1

44
Q

WNT7 and LMX1 lead to a limb with an

A

Extensor muscle side and a flexor muscle side

45
Q

Disruption of the proximal-distal development of the limbs results from loss of

A

FGF signaling

46
Q

Disruption of the proximal-distal development of the limbs can result in

A

Amelia (lack of limb), Meromelia (partial lack of limb), and adactylyl (absense of digits)

47
Q

Polydactyly (extra digits) and syndactylyl (fusion of digits) may be the result of

A

BMP or SHH disregulation or disruption

48
Q

At 7 weeks, what happens to the limbs?

A

They rotate

49
Q

Most cartilage templates of limb bones form between

A

5 and 12 weeks

50
Q

Ossification of proximal bones in the upper limb begins in the

A

7th week

51
Q

Ossification of proximal bones in the lower limb begins in the

A

8th week

52
Q

Most bones show ossification by the 12th week, although ischium and pubis not until the

A

15th and 20th weeks

53
Q

Smaller tarsal and carpal bones are not ossified until

A

Childhood

54
Q

As the AER advances distally with mesenchymal cell proliferation, proximal mesenchymal cells differentiate into

A

Chondroblasts (during week 6)

55
Q

Bone is vascular and replaces the avascular cartilage, which has a size limit due to reliance on

A

Diffusion through matrix for nutrients/waste exchange

56
Q

Cartilage calcification in the diaphysis (shaft) of long bones results in poor oxygen diffusion through the

A

Avascular cartilage

57
Q

As a result, the cartilaghe breaks down and is removed by

A

Osteoclasts

58
Q

Blood vessels invade the diaphysis and are accompanied by

A

Osteoblasts

59
Q

As cartilage is removed by osteoclasts, osteoblasts secrete bone matrix to form the

-occurs during prenatal development

A

Primary ossification center

60
Q

Primary ossification centers are formed during prenatal development and are present in all long bones of limbs by the

A

12th week of development

61
Q

At birth, diaphyses of bones are completely ossified, but the ends, the epiphyses, are still

A

Hyaline cartilage

62
Q

Primary and secondary ossification centers form on either side of a cartilaginous

A

Epiphyseal growth plate

63
Q

The growth plate is made of hyaline cartilage that has chondrocytes that can proliferate in response to

A

Growth hormone from adenohypohpysis

64
Q

Located at the growth plate retain the ability to divide when stimulated by growth factors in order to increase length of long bones

A

Chondrocytes

65
Q

Once growth is completed into adulthood (20-25 years of age), the original primary and secondary ossification centers will meet as bone fills in the growth plates to
form the

A

Epiphyseal line (and bone lengthening stops)

66
Q

The most common form of skeletal dysplasia (1/20,000 live births) and primarily affects long bones

A

Achondroplasia

67
Q

A gene associated with achondroplasia is

A

FGFR3

68
Q

One of the results of achondroplasia is shortened extremities due to reduced chondrocyte proliferation at

A

Growth plates

69
Q

Occurs while connective tissues are developing in somatic mesoderm

A

Muscle formation

70
Q

Somitic mesoderm invades somatic mesoderm during

A

Week 5

71
Q

Develops from ventral and dorsal condensations of somitic mesenchyme

A

Limb musculature

72
Q

The dorsal mass forms

A

Extensors and supinators of upper limb

and

Extensors and abductors of lower limb

73
Q

The ventral mass forms

A

Flexors and pronators of upper limb

and

Flexors and adductors of lower limb

74
Q

Based on induction of neuroepithelium to form neurons and neuroglia of the CNS and of neural crest to form neurons and neuroglia of the PNS

A

Nervous System Formation

75
Q

Based on origins from somites and somatic mesoderm

A

MSK formation

76
Q

Transforms the flat trilaminar disc into a cylindrical, C-shaped embryo whose limb buds project from the anterolateral wall

A

Body folding

77
Q

Involves orchestration of somatic mesoderm differentiation and migration of myotome myoblast cells with their innervation

A

Limb formation

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