Embryology: Back & Shoulder

Question 1

mesoderm

Answer 1

formed during gastrulation, gives rise to lateral plate mesoderm, intermediate mesoderm, and paraxial mesoderm

Question 2

paraxial mesoderm–>

Answer 2

somitomeres–> somites

Question 3

lateral plate mesoderm

Answer 3

bones- limbs, sternum

dermis- neck, trunk, and limbs

Question 4

intermediate mesoderm

Answer 4

urogenital system

Question 5

somitomeres

Answer 5

primordium of somites

Question 6

somitogenesis

Answer 6

paraxial mesoderm–> somitomeres–> somites

Question 7

sclerotome

Answer 7

Origin: core of somites
Comp: mesenchyme (embryonic connective tissue)
Dest. vertebrae, ribs, and annulus fibrosus

Question 8

mesenchyme

Answer 8

embryonic connective tissue, formed by all 3 germ layers; arise from somites of mesoderm

Question 9

dermatome

Answer 9

Origin: dorsal region of the somite
Comp:
Dest.: deep surface of back, dermis

Question 10

myotome

Answer 10

Origin: dorsomedial edge of somites
Comp:
Dest.: myoblasts that give rise to skeletal muscles of neck, trunk, and limbs

Question 11

nucleus pulposus

Answer 11

notochord > mesoderm

Question 12

annulus fibrosus

Answer 12

sclertome> somite> somitomere> paraxial mesoderm

Question 13

myoblasts

Answer 13

myotome > somite > paraxial mesoderm

Question 14

epaxial

Answer 14

dorsal region of myotome

Question 15

hypaxial

Answer 15

ventral region hypaxial myoblasts > myotome

Question 16

DPR

Answer 16

dorsal primary rami, innervate epaxial myoblasts that give rise to intrinsic back muscles

Question 17

VPR

Answer 17

ventral primary rami, innervate hypaxial myoblasts that give rise to muscles of the lateral trunk, limbs, ect.

Question 18

limb buds

Answer 18

outer layer: surface ectoderm

inner layer: parietal lateral plate mesoderm

Question 19

proximal-distal axis

Answer 19

growth from the bud to the tip of the limb bud

Signaling: AER apical ectodermal ridge

Question 20

preaxial-postaxial axis

Answer 20

postaxial structures: ulna and 5th digit

preaxial structure: radius and pollex

Question 21

dorsal-ventral axis

Answer 21

anterior-posterior direction in adults

signaling: surface ectoderm sleeve

Question 22

apical ectodermal ridge

Answer 22

a region of surface ectoderm that induces differentiation in underlying mesenchyme (according to the Progress Zone model)

Question 23

zone of polarizing activity

Answer 23

a mesenchymal region on the post-axial margin of the limb bud signals development of the pre-post axial limb pattern

Question 24

hand and foot plates

Answer 24

terminal portion of limb buds
digital rays: condensations of limbs
apoptosis separates the digits (except in ducks)

Question 25

wrist and ankle constrictures

Answer 25

the structures that separate hand and foot plates from limb plates

Question 26

ectodermal sleeve

Answer 26

what: surface ectoderm
role: dorsal-ventral patterning of lmib

Question 27

dorsal muscle mass

Answer 27

what: limb myoblasts on dorsal surface
innervation: VPR posterior divisions

Question 28

ventral muscle mass

Answer 28

what: limb myoblasts on ventral surface
innervation: VPR anterior divisions

Question 29

horizontal flexion of the limb

Answer 29

upper limb: lateral rotation (anatomical position)

lower limb: medial rotation

Question 30

lower limb rotation

Answer 30

medial— so muscles derived from the dorsal muscle mass and knee joint are found on the anterior aspect of the lower limb

Question 31

somitomeres 1-7

Answer 31

form the occipital region and skull

Question 32

the detloid is an example of a myotome that

Answer 32

split to also form the teres minor

Question 33

the erector spinae is an example of a myotome that

Answer 33

that fused to form a muscle