14_Devo Block 3.1 Musculoskeletal System

Front 1

What embryonic progenitor tissues are used to form the skeleton? What are progenitor skeletal cells?

Back 1

Mesoderm. Mensenchyme

Front 2

Skeletal progenitor mesenchyme is derived from different tissues based on where it is. In the Trunk progenitors are derived from two sources: (2) In the Head, they're derived from: (2) p.3

Back 2

Trunk: Paraxial and Somatic Mesoderm
Head: Neural Crest Ectomesenchyme, Head Mesoderm

Front 3

Define Preskeletal Condensation

Back 3

It's the site of future bone/cartilage formation.

Front 4

STFM (skeletal tissue forming mesenchyme) produce two important TFs. What are they what do they induce?

Back 4

STFM producing Sox-9 induces cartilage formation
STFM producing Runx-2 produces bone

Front 5

What happens to mice with RunX Null Mutation?

Back 5

They become cyanotic and die bc they do not from bone, they're ribs are flexible cartilage that compress lungs.

Front 6

Describe how cartilage forms.

Back 6

preskeletal condensation of STFM (under influence of signals from nearby tissue) --> Sox9 is produced --> condroblasts --> secrete cartilage matrix, no chondrocytes --> cartilage.

Front 7

What is the primary ossification center?

Back 7

Initial ossification center in a developing bone. Long bone = shaft. Flat bone = center. Controlled by hormones.

Front 8

What is bone age?

Back 8

Amount of epiphyseal cartilage that's retained.

Front 9

Cells from which half of the sclerotome contributes to the formation of the vertebral body, small parts of the neural arch and distal rib? (p7):

Back 9

Anterior half

Front 10

What is the sclerotome?

Back 10

See your notes, p1b. They are the cells that arise from the somatocoel when the epithelial mesenchym of the somite reverts back to scleratome mesenchyme.

Front 11

Cells from which half of the sclerotome contributes to the formation of the ventral body, transverse process, proximal rib, main part of distal rib and main part of neural arch?

Back 11

Posterior half

Front 12

What controls regionalization of the vertebral column (e.g. cervical, lumbar, etc)? (p.7)

Back 12

Nested expression of Hox genes along the cranial-caudal axis of the embryo

Front 13

What controls Hox expression?

Back 13

Retinoic acid

Front 14

Null mutation of Hox expression causes what? What about gain of function?

Back 14

Null mutation = cranialization of vertebral segments.
Gain of function = caudalizes vertebral segments.

Front 15

What structure allows for growth in the vertebra? (p8)

Back 15

Neural Central Junction

Front 16

Describe Klippel-Feil Sequence:
1. Frequency/Genetics
2. Characteristics (4)
3. Associated with:
4. % have (3)

Back 16

1. 1/40,000; Recessive
2. Several fused cervical vertebrae, shortened neck, low nuchal hair line, limited cervical spine motility
3. Associated with Genitourinary, cardiopulmonary, hearing defects
4. 20-30% have undescended scapulae, cervical rib, scoliosis (60%)

Front 17

Describe Sacralization

(BTW: How many Lumbars and Sacrum vertebrae are there?)

Back 17

Sacralization: Fusion of 5th lumbar vertebrae to sacrum. Thus it appears that there are 4 lumbar vertebrae and 6 fused sacral vertebrae.
(5 Lumbar and 5 Sacral)

Front 18

Describe Lumbarization. Is this better or worse than Sacralization?

Back 18

1st sacral verebrae is not fused to the sacrum. Thus it appears that there are 6 lumbar vertebrae and 4 sacral vertebrae. This causes hypermobility and that tends to cause more problems than lumbarization.

Front 19

Failure of fusion of the neural arches of vertebra:

Back 19

Dysraphism

Front 20

Condition where one or a few adjacent vertebrae have unfused spinous processes:
1. What is the major classification of this?
2. What is the mild asymptomatic form of this?

Back 20

Spina Bifida
1. Dyraphism
2. Spina bifida occulta

Front 21

What is the primordial tissue for:
1. Proximal Rib
2. Distal Rib
3. Sternum

Back 21

1. Scleratome and Somatocoel
2. Lateral scleratome
3. Somatic mesoderm

Front 22

Posterior depression of sternum:
Ventral protrusion of sternum:

Back 22

Pectus Excavatum
Pectus Carniatum

Front 23

Classify these skull bones as cranial or viscerocranium and endochondrial or intramembranous ossification.

Back 23

1. Chondrocranium (Cranium/Endo)
2. Fascial Bones (Viscero/Intra)
3. Jaws (Viscero/Intra)
4. Calvaria (Cranium/Intra)
5. Ossicles (Viscero/Endo)
6. Styloid process (Viscero/Endo)

Front 24

The skull is derived from two germ layers:

Back 24

Paraxial Mesoderm and Neural Crest Ectomesenchyme

Front 25

The Chondrocranium is composed of four bones:

Back 25

1. Petrous portion of temporal bone. (paired)
2. Base of occipital bone (unpaired)
3. Spenoid (unpaired)
4. Ethmoid (unpaired)

Front 26

In the chondrocranium, cartilages forming above the pituitary are derived from:
Cartilages forming below pituitary:

Back 26

Above: Neural crest ectomesenchyme
Below: Occipital somite (1-4) sclaratome tissue

Front 27

Where are the growth plates in the cranium?

Back 27

Between the Sphenoid and Ethmoid and between the Sphenoid and Occipital.

Front 28

Intersections between cranial sutures that run perpendicular to each other are called:
What is they're function?

Back 28

Fontanelles.
Function is to allow bones to interlock as pass through birth canal.

Front 29

Saggital sutures fusing prematurely cause:
Coronal sutures fusing prematurely cause:

Back 29

Saggital: Scaphocephaly
Coronal: Acrocephaly (tall) or Brachycephaly (wide, short) skull

Front 30

Craniosynostosis is associated with mutations in:

Back 30

FGF receptor

Front 31

Microcephaly?

Back 31

Normal face size but calvaria is small due to defect or absence of brain growth.

Front 32

Vertebrae are derived from:
Intervertebral discs are derived from:

Back 32

Vert: Sclerotome portion of somites
IV discs: scleratome (and perhaps notochord)

Front 33

What is Generalized Tissue Dysplasia?

Back 33

a defect in Extracellular Matrix (ECM) affecting growth in one part or all of the skeleton.

Front 34

What Generalized Skeletal Tissue Dysplasia is an example of Germ Line Mosaicism?

Back 34

Achondroplasia

Front 35

What is the primary precursor for muscle tissue?

Back 35

Mesoderm

Front 36

What are the derivatives of:
1. Skeletal m
2. Smooth, visceral smooth and cardiac muscle
3. Vascular smooth m.
4. Smooth m of constrictor and dilator pupilae m; myoepithelia cells of mammary and sweat glands:

Back 36

1. Paraxial mesoderm
2. Splanchnic mesoderm
3. Local mesoderm
4. Ectoderm