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Flashcards in MS devo Deck (52):
1

What does paraxial mesoderm form in skeletal development?

vertebral columns, ribs, neurocranium

2

What does lateral plate mesoderm form in skeletal development?

pectoral girdle, limbs, sternum

3

What do neural crest cells form in skeletal development?

viscerocranium (bones on the front of your face), hyoid bone

4

Why do bones form through intramembranous ossification?

more rapid formation in areas urgently needed by fetus

ex: mandible, need for sucking on boobs

5

What makes up the axial skeleton?

vertebrae
ribs
sternum
skull

6

What makes up the appendicular skeleton?

pectoral girdle
pelvic girdle
limb bones

7

What does the viscerocranium (anterolateral facial bones) form from?

neural crest cells

8

What does the neurocranium form from?

paraxial mesoderm

(occipital somites)

9

What makes up the chondrocranium and how is it formed?

base of the skull (sphenoid, petrous temporal, portion of occipital)

form by endochondral ossification

10

What is the membranous neurocranium and how is it formed?

everything except the chondrocranium

form by intramembranous ossification

11

At what age do your skull sutures fuse?

5-7 yrs

12

What are the different fontanelles?

fontanelles: enlarged membranous spaces where more than 2 bones form

anterior fontanelle (largest on top of head)
anterolateral/sphenoidal fontanelle
posteriorlateral/mastoid fontanelle
posterior fontanelle

13

What is craniosynostosis?

premature closure of sutures

14

What happens if your saggital suture closes too early?

You have scaphocephaly.

your head is really long and skinny (like your face gets squished on either side

15

What happens if you coronal suture closes too early?

You have brachycephaly.

your head looks like a really wide and ugly football

16

In relation to the axial skeleton, what is NOT formed by paraxial mesoderm?

sternum
part of the skull

17

In relation to axial skeleton formation, what structures are derived from paraxial mesoderm?

vertebrae
annulus fibrosis of intervertebral discs
ribs
neurocranium

18

When do vertebrae start to develop?

4th week: sclerotome cells surround neural tube and notochord

19

What happens during vertebral resegmentation?

sclerotomes are devided in half: a less dense cranial portion, and a more dense caudal portion.

resegmentation: a cranial (less dense) and a caudal (more dense) segment FROM NEIGHBORING SCLEROTOMES meet up and join

20

What forms the annulus fibrosus of IV discs?

Dense (caudal) portion of sclerotome

21

How do the ribs develop?

they grow out as costal processes from developing thoracic vertebrae

22

How and when is the sternum induced to form?

induced to form by ribs growing anteriorly towards midline

10th week

sternum develops as two sternal bars from LATERAL plate somatic mesoderm

23

What does the appendicular skeleton develop from?

lateral plate somatic mesoderm

24

When does endochondral ossification take place?

5th week: mesenchyme buds start to form

6th week: hyaline cartilage models start to form (finished by 8th week)

25

When does ossification begin in long bones?

primary ossification centers appear around 7/8th week

26

What is achondroplasia?

disturbance of endochondral ossification
makes you really short

like aleah from teen mom

27

What is skeletal muscle derived from?

paraxial mesoderm

28

What is cardiac muscle derived from?

intraembryonic splanchnic mesoderm

29

What is smooth muscle derived from?

intraembryonic splanchnic mesoderm

30

When do myoblasts actively contract?

7th week

31

Where are progenitor cells for muscle tissues located on the dermomyotome?

vertrolateral lips (VLL)
dorsalmedial lips (DML)

32

What does the lateral somatic frontier separate?

paraxial mesoderm from lateral plate mesoderm

(primaxial domain and abaxial domain)

33

Where is the primaxial domain and what does it contain?

surrounds neural tube

contains only somite derived cells from DML, VLL

34

Where is the abaxial domain and what does it contain?

located laterally to primaxial domain

parietal layer of lateral plate mesoderm with a few somite derived cells (some VLL cells migrate across lateral somatic frontier)

35

What does the primaxial domain form?

back m.
shoulder girdle m.
intercostal m.

36

What does the abaxial domain form?

infrahyoid m.
pec major and minor m.
abdominal wall mm.
limb m.

37

What are epaxial muscles and what innervates them?

back muscles

dorsal primary rami

38

What are hypaxial muscles and what innervates them/

muscles of limb and body wall

ventral primary rami

39

What smooth muscles are derived from ectoderm?

neuroectoderm: dialate eyes

surface ectoderm: my epithelial cells of mammary, salivary, sweat glands

40

In general, what germ layer is muscle from?

mesoderm

41

When do limb buds emerge?

end of week 4

upper before lower

42

What is the structure of a limb bud?

mesenchymal core surrounded by surface ectoderm

43

What does the apical ectodermal ridge (AER) do?

signals nearby mesenchyme to keep being undiffentiated and dividing (called the progress zone)

44

What are cells further away from AER doing?

differentiating into cartilage, muscle

45

In what direction do limbs grow?

proximal to distal

46

How do the limbs rotate?

UL: rotates 90 deg laterally (so that thumb faces laterally)

LL: rotates 90 deg medially (big toe faces medial)

47

How and when do your hands/feet form?

6th week: cute little paddles

end of 6th week: mesechyme grows into paddles forming digital rays (outline of future digits)

cells inbetween fingers/toes in AER die

end of 8th week: mesenchyme differentiates into hyaline cartilage models

48

meromelia

absence of part of a limb

49

amelia

absence of whole limb

50

polydactyly

extra digits

51

syndactyly

fewer digits

52

What drug fucked up kid's limbs?

thalidomide