Musculoskeletal Development Flashcards Preview

Anatomy and Radiology - Test 1 > Musculoskeletal Development > Flashcards

Flashcards in Musculoskeletal Development Deck (48):
1

Paraxial mesoderm gives rise to

Most of axial skeleton, most skeletal muscles, and dermis of the skin

2

Lateral plate mesoderm gives ride to

Pectoral and pelvic girdle, sternum, and long bones of the limbs

3

Somite formation process

Paraxial mesoderm proliferates and organizes into two columns on either side of notochord
Longitudinal columns differentiate into series of paired masses called somites

4

Occipital somites form

Occipital bone

5

Caudal occipital somites form

First cervical vertebra

6

Sequence of somite formation

Rostral to caudal

7

Somite regions

Sclerotome
Myotome
Dermatome

8

Sclerotome is future

Axial skeleton

9

Myotome is future

skeletal muscles

10

Dermatome is future

Dermis of skin in axial regions

11

Scelrotome migration

Cells on medial side begin to migrate toward notochord and neural tube

12

What forms vertebral arch

Dorsally migrating sclerotomes that pass posterior to neural tube

13

What forms vertbral body

Ventral migrating sclerotome cells that surround and incorporate the ventral side of the neural tube

14

What happens to migrated slcerotome cells

Programmed cell death that shapes into primitive vertebral body and neural arch

15

Somite resegmentation

Somites will split into a rostral and caudal part
Rostral migrates and fuses with migrating somite cells from the caudal part of the more rostral somite

16

Purpose of somite resegmentation

Allows growing spinal nerve to pass between adjacent vertebrae

17

CS1

Rostral half migrates to fuse with lower occipital somite to form occipital bone along with the rostral four occipital somites

18

First cervical spine nerve located

Superior to the first cervical vertebrae

19

Rib development

Develop from costal processes of developing thoracic vertebrae (somites)
Elongate in week 5 to form ribs

20

Sternum development

Lateral plate somatic mesoderm differentiates into mesenchyme
Mesenchyme migrates anteriorly and condenses to form sternal bars
Sternal bars fuse at cranial ends first and then "zip"

21

Dermatome migration

Migrates to lateral part of somite to form dermis of the skin
Everywhere but head

22

Myotome migration

Most migrates ventrally, while some dorsal
Ventrally forms hypomere (muscles and limbs)
Dorsally forms epimere (true back muscles)

23

Hypomere

Becomes body wall and limbs
Hypomere of thorax and abdomen forms three layers

24

Muscles derived from hypomere innervated by

ventral primary rami of spinal nerves

25

Epimere

Migrates minimally and stays on posterior side of vertebral column

26

Epimere derivatives innervated by

dorsal primary rami of spinal nerves

27

Limb development

At end of fourth week, limb buds begin forming upper limb and lower limb
Somatic mesoderm induces ectoderm to form AER
AER induces mesoderm to continue dividing which lengthens the limb

28

Upper limb development spinal cord level

C4-T1

29

Lower limb development spinal cord level

L1-S3/4

30

Limb buds composed of

Composed of surface ectoderm and core of somatic mesoderm

31

AER

Apical ectodermal ridge
Induced by ectoderm
Induces mesoderm to continue divding and legnthen limb

32

Bones of limbs develop from

Mesenchyme from somatic lateral plate mesoderm that first forms cartilage

33

Precursor to bone development

Cartilage

34

Lateral plate mesoderm also contributes to cartilage of

Pectoral and pelvic girdles of each limb

35

What happens as hypomere enters the limb?

Splits into a ventral muscle mass and odrosal muscle mass

36

Ventral and dorsal muscle mass functions

Ventral - flexors, pronators, adductors
Dorsal - extensors, supinators, abductors

37

Dorsal and ventral mass innervation

Respective primary rami

38

Dorsal and ventral branches of the VENTRAL primary rami correlate with

posterior and anterior divisions of the brachial plexus

39

Timeline of limb development

5 weeks from day 24(upper)/28(lower)

40

Most sensitive period of limb formation

Weeks 4-5

41

What sculpts inter-digit regions

AER is turned off so cells stop dividing

42

Limb rotation

During development, upper limbs rotate laterally and lower limbs rotate medially

43

Meromelia

Absence of part of a limb

44

Polydactyly

Presence of extra digits

45

Amelia

Absence of one or more limbs

46

Syndactyly

Fusing of digits

47

Simple syndactyly

Cutaneous syndactyly
Failure of mesenchyme between digital rays to break down

48

Complex syndactyly

Digits joined by bone or cartilaginous union