Musculoskeletal System Flashcards Preview

Anatomy 6511 > Musculoskeletal System > Flashcards

Flashcards in Musculoskeletal System Deck (63)
1

Appendicular Skeleton

Pectoral girdle
Pelvic girdle
Limb bones

2

Axial Skeleton

Vertebrae
Ribs
Sternum
Skull

3

Mesoderm

Dev to Paraxial mesoderm (somites)
Lateral plate somatic mesoderm

origin for musculoskeletal system

4

Neural crest cells

Another origin for musculoskeletal system

5

Paraxial mesoderm -->

Mesenchyme --> Vertebral column, ribs, & neurocranium

6

Lateral plate mesoderm -->

Mesenchyme --> Pectoral girdle, pelvic girdle, limbs, & sternum

7

Neural crest cells-->

Mesenchyme--> Viscerocranium & hyoid bone

8

Sclerotome

forms all of the axial skeleton except:
Sternum & a portion of the skull

9

Paraxial Mesoderm Derivatives

Vertebrae
Annulus fibrosus of intervertebral discs
Ribs
Neurocranium

10

Vertebrae Development - 4th week

4th week: sclerotome cells surround neural tube & notochord

11

Each sclerotome segment has

Less dense cranial portion
Dense caudal portion

12

Dense portion (sclerotome

Annulus fibrosus of IV discs
Fuses with less dense portion of sclerotome immediately inferior to form the vertebral body

13

Sclerotomes Undergo Resegmentation

6th week: chondrification occurs

Ossification:
Begins 7th week
3-5 years: vertebral arch halves fuse
3-6 years: vertebral arch fuses with body
~25 years: ossification complete

14

Dev of Annulus Fibrosus of IV Discs

Sclerotome-->
intersegmental mesenchyme -->annulus fibrosus

15

Rib dev.

Grow out as lateral extensions of costal processes developing from thoracic vertebrae & wrap around anteriorly

Synovial joint forms where costal process meets vertebra

16

Development of the Sternum

Induced to form by ribs at ventral midline from lateral plate somatic mesoderm
10th week:
Develops as two sternal bars that will fuse cranially to caudally
Later fuse to form manubrium, sternal body, and xiphoid process

17

Viscerocranium

anterolateral facial bones

18

Neurocranium

bones encasing the brain

19

Development of the Neurocranium

Occipital somites form a portion of the neurocranium

20

Cartilaginous Neurocranium

Base of skull
Sphenoid, petrous portion of temporal bone, portion of occipital bone
Form by endochondral ossification

All other parts of
Form by intramembranous

21

Membranous Neurocranium

Flat bones that surround the brain
Formed by intramembranous ossification

22

Fontanelles

Enlarged membranous spaces where more than 2 bones meet

23

Development of Appendicular Skeleton

Differentiates from mesenchyme of lateral plate somatic mesoderm

24

Endochondral Ossification

5th week: condensations of mesenchyme appear in limb buds

6th week: mesenchymal bone models undergo chondrification to form hyaline cartilage models

7th/8th week: ossification begins in long bones
Occurs initially in diaphysis from primary ossification centers

25

Skeletal muscle origin

Derived from paraxial mesoderm

26

Cardiac muscle origin

Cardiac muscle
Derived from intraembryonic splanchnic mesoderm surrounding developing heart

27

Smooth muscle origin

Smooth muscle
Of G.I. tract: Derived from intraembryonic splanchnic mesoderm surrounding gut tube

28

Somites differentiate into:

Sclerotome
Myotome
Dermatome
-skeletal muscle dev.

29

Somites give rise to:

Axial skeleton (most)
Associated musculature
Overlying dermis of back

30

Myoblasts

specialized mesoderm cells
Fuse together to form skeletal muscle
Actively contract by week 7

31

Progenitor cells for muscle tissues derived from

the ventrolateral and dorsomedial lips of the dermomyotome

32

Lateral somitic frontier

separates paraxial mesoderm from lateral plate somatic mesoderm

33

Primaxial domain

surrounds neural tube and contains only somite-derived cells **adjacent to the neural tube -very close to it.

Dorsomedial lip (DML) & a few Ventrolateral lip (VLL) cells left at the myotome will form the:
Musculature of the back
Shoulder girdle muscles
Intercostal muscles

34

Abaxial domain

parietal layer of lateral plate mesodem with somite-derived cells

Most Ventrolateral lip (VLL) myoblasts migrate across the frontier into lateral plate somatic mesoderm to form:
Infrahyoid muscles
Pectoralis major & minor muscles
Abdominal wall muscles
Limb muscles

35

Myotome

Each myotome divides into:
Epaxial group (dorsal/posterior)
Hypaxial group (ventral/anterior)

Each spinal nerve divides into:
Dorsal primary ramus
Ventral primary ramus:

36

Epaxial muscles -->

back muscles -->dorsal primary rami

37

Hypaxial muscles -->

muscles of the limbs + body wall --> ventral primary rami

38

Cardiac Muscle dev

Derived from intraembryonic splanchnic mesoderm
Gives rise to mesenchyme surrounding developing heart tube

39

Smooth Muscle dev

Derived from intraembryonic splanchnic mesoderm
Wall of gut & gut tube derivatives
Most large arteries (i.e., aorta)

40

Neuroectoderm

Sphincter pupillae m. & dilator pupillae m. of iris
-derived from ectoderm.

41

Surface ectoderm

Myoepithelial cells of mammary, salivary, & sweat glands

42

Limb Development

Limb buds emerge toward end of week 4
Upper limbs (UL) appear 1st
Lower limbs (LL) appear 1-2 days later

43

Limb Bud

Core of mesenchyme, lined by surface ectoderm

Mesenchyme forms connective tissue of the limb
Cartilage, bone, dermis, blood vessels

44

Elongation of the Limbs

Apical ectodermal ridge (AER) sends signaling factors to nearby mesenchyme of progress zone
Keeps cells undifferentiated and rapidly dividing to form more limb tissue

Limb grows proximally to distally

45

Migratory Cells Invade Limb Bud

Melanocytes
From neural crest
Sensory axons & Schwann cells
From neural crest
Myoblasts
From myotome of VLL
Motor axons
From neural

46

Outgrowth of Limbs, Weeks

4-8. Epaxial muscles
Dorsal primary rami

Hypaxial muscles
Ventral primary rami
Will divide to form dorsal & ventral branches to compartments

47

Limb buds initially grow straight out

laterally, followed by:
UL lateral rotation by 90° & LL medial rotation by 90 degrees

48

Week 6: “paddle stage”

End of week 6
Mesenchyme is condensing to form digital rays
Outlines of future digits

Organized apoptosis of cells in AER divides paddle into 5 digits

End of week 8
Mesenchyme will differentiate as hyaline cartilage in digits due to AER induction

49

Apoptosis in AER forms

Digits

50

Meromelia

absence of part of a limb

51

Amelia

absence of entire limb

52

Polydactyly

extra digits

53

Syndactyly

two or more fused digits

54

Sternum

Lateral plate mesoderm

55

Skull

Neural crest cells in origin

56

Portion of occipital somite

fuses with cranial portion of cranial 1. Bottom of spinal cord tapers off.

57

Manubrium

first to form, forms downward.

58

Each vertebral level will have

Ossification centers, begin to ossify from 12th week onward.

59

Bottom of skull with nerves

Endochondrial ossification

60

Rest of skull (flat bones)

Intermembranous ossification

61

Myogenic

Myoblasts on hold

62

Primaxial and abaxial

Helps determine dorsal and ventral ramus innervation.

63

Local molecular clues differentiate between

Cardiac and smooth muscle.