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Flashcards in Axial Skeleton Development Deck (70):
1

somitomeres arise from where

paraxial mesoderm

2

what day do the somitomeres arise ?

day 18 approx

3

What day to the somites begin to form ?

day 20

4

somites differentiate into what ?

sclerotome and dermomyotome

5

how many occpipital, cervical, thoracic, lumbar, sacral and coccygeal somtes are there respectivelty

4,8,12,5,5,8-10

6

the ____________occipital somite and the cranial portion of the ________ cervical sclerotome help form the base of the occpital bone

fourth, first

7

how is the atlas formed ?

caudal half of the first cervical scleroome and the cranial half of the second cervical sclerotome

8

how is the first thoracic vertebrae formed ?

caudal half of the 8th cervical and the cranial half of the first thoracic sclerotome

9

the ribs form from

paraxial mesoderm

10

sterum forms from

somatic mesoderm

11

where do the intervertebral disks arise from ?>

a thin layer of mesenchymal cells between the cranial and caudal portions of the original sclerotome

12

notochord gives rise to what part of the interertebral disks

nucleus pulposis

13

annulus fibrosis develops from what /

sclerotome

14

scoliosis

abnormal curvature because of improper fusion or formation of the vertebral column

15

pescavatum

sucken in chest, deformity in sternal bone

16

hemivertebrae

abnormal fusion resulting from misformed vertebrae

17

spina bifida occulta

incomplete neural disk usually asymptomatic and accomapnied by a patch of hair over the lesion

18

Klippel Feil syndrome

short neck from reduced number of cervical vetebrae

19

chordoma

remnants of notochord may give rise to malignant tumors that invade bone they develop at the base of the skull in the lumbar region

20

vast majority of skeletal muscles are derived from what

paraxial mesoderm

21

muscles of the head arise from

somitomeres

22

muscles of the tonque, torso and limbs arise from

somites

23

extrinsic muscles of eye develop from

pre-optic somites

24

dorsal part of the myotome is formed by _____________ which migrate farther to form _____________ muscles

primaxial muscle cells, epaxial (instrinisc)

25

lateral part of myotome is formed by _____________ muscle cell precursors and gives rise to ____ muscles

abaxial, hypaxial

26

muscle dystrophies

conditions that result in weakness and muscle atrophy

27

accessory muscles

rectus sternalis

28

polan anomaly

congentical absence of pectoralis major

29

congenital torticollis

contracture or shortening of the sternocleidomastoid

30

slcerotome

gives rise to mesenchymal clles

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

61

dura mater arises from

ectoderm

62

spina bifida occulta

involves vertebral arch, patch of hair

63

spina bifida cystica

involves a cyst like sac containing CSF

64

spina bifida with meningocele

onyl meninges

65

spina bifida with meningomyelocele

involves some neural tissue (roootlets) meninges and CSF

66

spina bifida with myeloschisis

neural folds fail to fuse posteriorly
spinal cord is open to exterior
SERIOUS

67

spinal dural sinus

indicated by a dimple through the lumbar region, indicates the region of closure of the caudal nueropore; can be connected through a fibrous cord to dura mater

68

tethered cord syndrome

defect in secondary neurulation; conus medullaris and filum terminale are abnormally fixed to the vertebral column; associated with lower limb and bladder control problems

69

hirschprungs disease

1-5,000
delay in passage of meconium
results in constipation, vomiting, abdominal distension and rupture of cecum
characteristic feature revealed by barium enema
results from mutation in RET protooncogene
neural crest fail to reach the hind gut

70

neurofibromatosis (type 1)

1 in 4000
congenital disorder that affects ALL derivatives of neural crest cells and results in nerve sheath tumors and cafe aulait spots (pigmented spots in the skin)