Axial Skeleton Development Flashcards Preview

Embryology > Axial Skeleton Development > Flashcards

Flashcards in Axial Skeleton Development Deck (70)
Loading flashcards...
31

mesemchyme develops into what three types of cells

fibroblasts, chondroblasts and osteoblasts

32

what gives rise to the sternum, shoulder and pelvic girdles

somatic layer of lateral place

33

what helps form many bones of the skull

neural crest cells

34

head somitomeres will form what parts othe the skull

cranial vault and the base of the skull

35

intramembranous ossification

occurs in mesencyme
forms a membranous sheat
mesenchyme condenses and becomes highly vascular
osteoblasts lay donw matrix
calcium is deposited
FLAT BONES of skull and most of the clavicle

36

endochondral osssification

from hyaline cartilage
occurs in preexisting cartilagenous model (starts by week 5)
occurs in the diaphysis (shaft)
cartilage cells hypertrophy, matrix becomes calcified and cells die
thin laye of bone is deposited under the perichondrium and becomes periosteum
invading cells differentiate into hemopoietic cells
LIMB bones

37

pathfinding

active movement of an axon toward a target

38

tropic substance

laminin related proteins

39

chemoaffinity hypothesis

axons can have differing affinities for molecules

40

pioneer axons

first axons to develop seem to play a role; there is a single axon that grows using the above methods to find a target and other axons follow

41

What are the ways an axon can find its target

tropic substnace
contact guidance theory
chemoaffinity hypothesis

42

growth cones

these are specializtion at the ends of an axon that are used to survey the environment

43

ventricular zone

layer of cells directly surrounding the ventricle

44

What are the three layers of the neural tube

ependymal layer-surrounds the central canal
mantle layer-middle layer contains cell bodies and astrocytes
marginal layer- contains nerve fibers and oligodendrocytes

45

sulcus limitans

separates the neural tube into dorsal and ventral areas

46

the mantle layer of the neural tube develops into two regions what are they

basal plate-motor cell bodies
alar plate- sensory relay cells

47

neural crest cells that remain close to the neural tube give rise to

ganglia (dorsal root and sensory ganglia for cranial nerves)

48

What three ways do the neural crest cells leave the neural tube ?

head and pharyngeal arches
autonomic ganglia in the torso
malanocytes

49

the last cells to leave the neural tube give rise too what cell type

melanocytes

50

What is the sequence of formation for spinal nerve

GSE
GVE
and then finally sensory GSA, and GVA

51

when does the process of myelination occur

late fetal period approx 20 weeks (motor before sensory)

52

when do the frontal lob tracts myelinate

2nd decade of life

53

myelination is largely complete by when

8 years of age

54

dermatome

area of the skin that is innervatedby a spinal cord segment, segmental and overlapping

55

myostome

innervation of skeletal muscle based on the relationship of the spinal nerve and somite

56

sympathetic innervation to head

t1-t4

57

sympathetic innervation to heart

t1-t4/5

58

sympathetic innervation to organs in the abdomen and pelvis

t5-t12

59

parasympathetics

vagus and S2,3 and 4

60

pia and arachnoid mater arise from

neural crest