Limb Development

Question 1

Preaxial region

Answer 1

thumb and radialis and anterior

Question 2

Postaxial region

Answer 2

little finger and ulna can be posterior

Question 3

Limb buds form when

Answer 3

4th week

Question 4

when do we have primary ossification

Answer 4

12th week

Question 5

when do we have digits

Answer 5

8th week

Question 6

what does the limb forming mesodorm release

Answer 6

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

forms the limb bud

Question 7

Stylopod

Answer 7

forms the humerus and the femur

Question 8

Zeugopod

Answer 8

forms the radius/ulna and the tibia and fibula

Question 9

Autopod

Answer 9

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

Question 10

what occurs at 5th week

Answer 10

hand and foot plates
chondrification centers appear

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

Question 11

what forms first upper or lower limbs?

Answer 11

upper limbs because more blood closer to the brain

Question 12

what forms in 6th week

Answer 12

digital rays of the hand

entire limb skeleton is cartilaginous

Question 13

what forms in week 7

Answer 13

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

Question 14

how does the upper limb rotate

Answer 14

90 degrees laterally occurs at week 7

Question 15

how does the lower limb rotate

Answer 15

90 degrees medially occurs at week 7

Question 16

what happens in the 8th week

Answer 16

separate digits are formed

apoptosis controlled by BMP

Question 17

limb musculature come from?

Answer 17

derived from the dorsolateral cells of the somite

hypomere

Question 18

torsion

Answer 18

happens at the lower limb

occurs at week 8 gives rise to the barber pole

Question 19

what goes into the limb bud arterial

Answer 19

intersegmental arteries from the dorsal aorta

gives rise to the primary axial artery

Question 20

Primary axial Artery

Answer 20

gives rise to the brachial artery in the upper arm

deep artery of the lower limb

after we get the remodeling of the arterys

Question 21

Club foot

Answer 21

Talipes Equinovarus

sole of foot turned medially and foot is inverted

happens in males more

Question 22

Developmental hip dysplasia

Answer 22

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

lots of dislocations

Question 23

what does Apical ectodermal ridge release

Answer 23

FGF4 and 8 to the mesoderm to stimulate growth

hox genes will make right shapes

Question 24

Dorsal surface patterning signaling:

Answer 24

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

Question 25

Ventral surface patterning signals:

Answer 25

the flexors are getting signaled by the BMP set up by AER

Question 26

Anterior posterior patterning signal

Answer 26

established by the zone of Polarizing Activity (ZPA) on the little finger side, posterior side

Question 27

what does zone of polarizing activity release and what do they do

Answer 27

SHH and retinoic acid

these form the 5th 4th and 3rd digit on the ulna side

Question 28

loss of ZPA

Answer 28

lost of digits on the posterior side

Question 29

up regulation of the ZPA

Answer 29

additional posterior elements or fingers (polydactyly)

Question 30

duplication of the ZPA

Answer 30

duplication of the posterior elements on both sides of the thumb

Question 31

Syndactyly

Answer 31

loss of Apoptosis and BMP
conjoined finger
happens in week 8

Question 32

Brachydactyly

Answer 32

short digits

Question 33

Meromelia

Answer 33

missing part of limb

problem with the FGF and AER weeks 4-8

Question 34

Phocomelia

Answer 34

hands and feet attached close to the body

problem with FGF and AER week 4-8

Question 35

Amelia

Answer 35

lack of limb
FGF and AER issue and occurs at week 5

can be caused by thalidomide

Question 36

forked or split food or hand

ectrodactyly

Answer 36

center of AER degenerating

hands: week 6
feet: week 7

Question 37

Arthrogryposis

Answer 37

congenital joint contractures
lead to neurological defects
muscular abnormalities