Flashcards in Axial Skeleton Development Deck (70)
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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
