Limb Development Flashcards

1
Q

Preaxial region

A

thumb and radialis and anterior

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2
Q

Postaxial region

A

little finger and ulna can be posterior

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3
Q

Limb buds form when

A

4th week

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4
Q

when do we have primary ossification

A

12th week

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5
Q

when do we have digits

A

8th week

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6
Q

what does the limb forming mesodorm release

A

it releases FGF 10 which acts on the surface ectoderm to make the Apical Ectodermal ridge (AER)

forms the limb bud

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7
Q

Stylopod

A

forms the humerus and the femur

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8
Q

Zeugopod

A

forms the radius/ulna and the tibia and fibula

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9
Q

Autopod

A

forms the carpels and the meta carpals, digits and the tarsals, and metatarsals and digits

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10
Q

what occurs at 5th week

A

hand and foot plates
chondrification centers appear

motor neurons from the spinal cord enter the limb buds
sensory neurons will follow

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11
Q

what forms first upper or lower limbs?

A

upper limbs because more blood closer to the brain

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12
Q

what forms in 6th week

A

digital rays of the hand

entire limb skeleton is cartilaginous

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13
Q

what forms in week 7

A

Digital rays of the feet
osteogenesis of the long bones
rotation of the limbs

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14
Q

how does the upper limb rotate

A

90 degrees laterally occurs at week 7

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15
Q

how does the lower limb rotate

A

90 degrees medially occurs at week 7

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16
Q

what happens in the 8th week

A

separate digits are formed

apoptosis controlled by BMP

17
Q

limb musculature come from?

A

derived from the dorsolateral cells of the somite

hypomere

18
Q

torsion

A

happens at the lower limb

occurs at week 8 gives rise to the barber pole

19
Q

what goes into the limb bud arterial

A

intersegmental arteries from the dorsal aorta

gives rise to the primary axial artery

20
Q

Primary axial Artery

A

gives rise to the brachial artery in the upper arm

deep artery of the lower limb

after we get the remodeling of the arterys

21
Q

Club foot

A

Talipes Equinovarus

sole of foot turned medially and foot is inverted

happens in males more

22
Q

Developmental hip dysplasia

A

more common in females
underdevelopment of the acetabulum of the hip bone
general joint laxity

lots of dislocations

23
Q

what does Apical ectodermal ridge release

A

FGF4 and 8 to the mesoderm to stimulate growth

hox genes will make right shapes

24
Q

Dorsal surface patterning signaling:

A

the extensors are getting signaled by wnt7 and are set up by the AER

25
Ventral surface patterning signals:
the flexors are getting signaled by the BMP set up by AER
26
Anterior posterior patterning signal
established by the zone of Polarizing Activity (ZPA) on the little finger side, posterior side
27
what does zone of polarizing activity release and what do they do
SHH and retinoic acid these form the 5th 4th and 3rd digit on the ulna side
28
loss of ZPA
lost of digits on the posterior side
29
up regulation of the ZPA
additional posterior elements or fingers (polydactyly)
30
duplication of the ZPA
duplication of the posterior elements on both sides of the thumb
31
Syndactyly
loss of Apoptosis and BMP conjoined finger happens in week 8
32
Brachydactyly
short digits
33
Meromelia
missing part of limb | problem with the FGF and AER weeks 4-8
34
Phocomelia
hands and feet attached close to the body | problem with FGF and AER week 4-8
35
Amelia
lack of limb FGF and AER issue and occurs at week 5 can be caused by thalidomide
36
forked or split food or hand | ectrodactyly
center of AER degenerating hands: week 6 feet: week 7
37
Arthrogryposis
congenital joint contractures lead to neurological defects muscular abnormalities