Limb Development

Front 1

What week do limbs begin to develop embryonically?

Back 1

Initiation of limb development starts at week three

Front 2

The lower extremity limb buds start at what vertebral levels?

Back 2

L3-L5

Front 3

At what week does development of the LE limb buds begin?

Back 3

Day 28 (week 4)

Front 4

LE follows UE development and catches up at what week?

Back 4

8

Front 5

The core of the limb bud is derived from what tissue?

Back 5

mesenchyme

Front 6

The limb bud is surrounded by what?

Back 6

An epithelial lining called "Ectodermal cap"

Front 7

What is the signal source at the distal part of the limb bud?

Back 7

AER (like the seam at the end of a hot pocket"
"growth along Proximal to distal axis.

Front 8

LE morphogenesis occurs from between what weeks?

Back 8

From week 4-8

Front 9

Describe the state of morphogenesis at Week 4

Back 9

Elevation of tissue at the level L3-L5

Front 10

Describe the state of morphogenesis at Week 4+

Back 10

Rounded proximal portions of the LE limb buds can be distinguished
from the more tapered distal parts

Front 11

Describe the state of morphogenesis at week 5+

Back 11

All three LE sections are present (Thighs Legs Feet are distinct), [Foot plates] are present.

Front 12

Describe morphogenesis of LE at week 6+

Back 12

[toe rays] are visible in the foot plates, but the rims of the foot plates remain smooth (cartilage models are forming)

Front 13

Describe morphogeneis at the end of week 6!!! What day?

Back 13

Day 47, medial rotation begins, toe rays are MORE prominent but rims of foot plates are still smooth. NOTE: LE's begin to flex toward the [parasagital] plane

Front 14

Describe morphogenisis at week 7

Back 14

LEs longer and feet have begun to approach eachother at midline (medial rotation continues)
NOTCHES in rims of footplates

Front 15

Describe Morphogenesis at week 8

Back 15

LE’s longer and all regions are defined including the toes.
(Programmed cell death has occurred in the tissues between the toe
rays –individual toes are seen.) Medial rotation of LE is complete.

Front 16

Amelia

Back 16

Absence of one or more limbs

Front 17

Meromelia

Back 17

Absence of part of a limb

Front 18

Phocomelia

Back 18

Phoco= seal
absence of proximal limb structures (flipper like distal portions are present)

Front 19

Polydactyly

Back 19

presence of extra digits or parts of digits

Front 20

Syndactyly

Back 20

Fusion of digits

Front 21

Lateral Plate Mesoderm
SOMATIC part gives rise to what?

Back 21

Body wall and limb

Front 22

What week are the tiniest buds present indicating limb development?

Back 22

Week3

Front 23

LPM SOMATIC mesoderm gives rise to what parts of the UE/LE?

Back 23

Bones, Joints, Cartilage, Ligaments, Tendons, Fascia, Bood/lymphatic vessels
(General CT, BONES AND BLOOD)

Front 24

Cartilage models of bones form how, when?

Back 24

Cartilage models of LE bones
mesenchymal core at the initially develop as condensations within the
beginning of week 6.

Front 25

When do primary ossificatino centers begin to appear in the long bones?

Back 25

Primary centers of ossification begin to appear in the long bones of the LE in the
8th to 12th weeks.

Front 26

LPM is divided into what two sections?

Back 26

Loop on neural tube side: Somatic
Loop on notochord side:
Visceral: Guts

Front 27

How is nural crest relevant to LE?

Back 27

Gives rise to peripheral Posterior Root ganglia and nervous system, as well as schwann cells and some melanocytes

Front 28

How is notochord relevant to LE?

Back 28

Notochord becomes Nucleus pulposus which can herniate into the spinal cord

Front 29

PAM (NOT LPM) divides into what 3 "tomes?"

Back 29

Dermatome: Dermis
Myotome: Sk MM of LE
Sclerotome: Vertebral Column

Front 30

What is chondrification? when does it begin?

Back 30

Appearance of hyaline cartilage models of long bones, begins in week 6 in LE.
Begins as condensations of mesenchymal core

Front 31

When does endochondral ossification begin?

Back 31

8th -12th week after primary centers of ossification appear.

Front 32

in what part of the long bones do primary centers of ossification appear? When?

Back 32

Diaphyses of LE long bones 8-12 weeks

Front 33

Secondary centers of ossification in LE are called what? When do they begin to ossify?

Back 33

Epiphyses, a few secondary might start around birth but the majority start after.

Front 34

Week?

Back 34

4

Front 35

Week?

Back 35

4

Front 36

Week?

Back 36

4+

Front 37

Week?

Back 37

5

Front 38

week?

Back 38

5

Front 39

Week?

Back 39

6

Front 40

What week?

Back 40

6

Front 41

Week?

Back 41

8

Front 42

Whas dis? think developing LE

Back 42

Mesenchymal condensations giving rise to hyaline cartilage outlines of the bones of LE

Front 43

Whats this? From whence did it come?

Back 43

mesenchyme from Somatic LPM

Front 44

Was dis? what week is this?

Back 44

AER, 4+

Front 45

Name for condition

Back 45

amelia

Front 46

This is the process of what?

Back 46

Endochondral ossification

Front 47

name of condition

Back 47

Phocomelia

Front 48

diagnosis

Back 48

Syndactyly

Front 49

Where does paraxial mesoderm begin to develop?

Back 49

along the sides of the neural tube

Front 50

Somites are derived from what?

Back 50

Paraxial Mesoderm

Front 51

Somites give rise to what in the LE?

Back 51

Muscles

Front 52

Muscles of the LE are derived from what cells?

Back 52

Somitic mesoderm (from somites) NOT MESENCHYME FROM LPM SOMATIC CELLS, DONT MISS THIS ON THE EXAM!!!!!!!

Front 53

How do MM cells get into the already packed mesenchymal areas making bones, ct, and vessels?

Back 53

Myogenic cells from the myotome (part of the somite) will migrate into the limb bud and
fuse to form the skeletal muscle of the LE.
The connectives tissues present within the limb bud (derived from somAtic mesoderm)
Guide and form the scaffolding for this muscle formation process.

Front 54

What are the derivations of the Dorsal, middle, and ventral parts of the Somite?

Back 54

Dermatome (dorsal) dermis (not epidermis)
Myotome (middle) MM and some NN
Sclerotome (stomach side) gives rise to Spinal Vertebrae
(I tried to make that easy to remember
D, M, S

Front 55

Somite migration cells travel towards the neural tube and towards the belly, going towards the belly they have to cross a point of no return, called:

Back 55

Lateral SOMITIC fronteir
It's like the rio grande, on mexico side they're all Mexicans, once they cross they have a grip of names that they can become. My favorite is friend, Than's favorite is Wife, Hayden's favorite is chingaso.

Front 56

What is the primaxial domain?

Back 56

Myotime that migrates to the Primary axis of the body, the spinal region.
Associated with Neural tube and notochord,

Front 57

What do myotomes and dermatome form in the primaxial domain?

Back 57

Myotome: True back muscles
Dermatome: Dermis of the back

Front 58

What is the Abaxial domain?

Back 58

Ab= away from the body's main axis (when we were fish we didn't have these somites, when we began to walk on land they were formed, Abaxial- away from the axis) to body wall and limbs.
YOu know what Myotome and dermatomes do.

Front 59

Describe the traditional way of labeling Primaxial and abaxial.

Back 59

Myotome was divided into Epimere (like Primaxial- true back) and Hypomere (like abaxial- body wall and limb)
but the MM are organized as a dorsal and ventral MM mass guided by the bones.
This initially was extremely segmented, but muscles twist and fuse and segementation is lost.

Front 60

What is the MM/Somite rule?

Back 60

Muscles are derived from the somites of the same area that innervates them
LE is area L2,3,4

Front 61

Define Dorsal and Ventral muscle masses

Back 61

Initially the generic limb buds can be described as having: : Dorsal surfaces (or sides): continuous with back
Ventral surfaces (or sides): continuous with “belly”

Front 62

Define the association of movement and Dorsal/ventral muscle masses

Back 62

Musculature associated with these surfaces or sides: Dorsal (surface) muscle mass: primarily extensors (& abductors)
Ventral (surface) muscle mass: primarily flexors (& adductors

Front 63

What in the freak is the Limb bud axis? What areas are they?

Back 63

imaginary line drawn through the femur to the 2nd digit inferiorly.
Preaxial portion/border: tibia and hallux (medial)
Postaxial portion/border: Fibula and the 5th

Front 64

Pre/Post axial MM are associated with what actions?

Back 64

Preaxial: from ventral MM Mass; Flexors/adductors)
Postaxial: from dorsal MM (extensors, abductors)
PreVee FAd (only need to memorize one)

Front 65

What happens to pre/postaxial regions with the medial rotation of the femur?

Back 65

Preaxial moves to medial poserior
Postaxial moves to lateral/anterior

Front 66

Medial rotation of the femur happens on what pt of the femur?

Back 66

Occurs embryonically from the distal half of the femur (hip NOT affected by the rotation)

Front 67

Preaxial muscles are from what MM mass, become what MM?

Back 67

Ventral MM mass,
Iliopsoas, Pectineus,
Adductor longus, magnus, other flexors and adductors

Front 68

Postaxial muscles are from what MM mass, become what MM?

Back 68

Dorsal MM mass, Gluteal MM, extensors and abductors

Front 69

What pt of the femur is affected by rotation?

Back 69

distal 1/2, so the muscles that act on everything distal to the hip, like at the knee, STJ, and ankle, are affected by rotation.

Front 70

Knee: preaxial MM, from what mass?

Back 70

Ventral Muscle mass
Become hamstrings (biceps femoris, semitendinosus, membranosus) and knee flexors

Front 71

The medial and posterior compartments of the thigh are derived from what "axial Muscles" and therefore what MM mass?

Back 71

Preaxial MM, ventral MM Mass

Front 72

Knee: postaxial MM, from what mass?

Back 72

Dorsal MM mass, becomes quadriceps femoris, knee extensors

Front 73

Preaxial MM, from what MM mass become what cmopartments of the leg?

Back 73

Ventral MM mass, posterior leg, plantar foot

Front 74

Preaxial MM, from what MM Mass, have what action at ankle, STJ, toes?

Back 74

Plantarflexion
Inversion
Flexion

Front 75

Postaxial MM, from what MM mass, become what compartment of the leg and foot?

Back 75

Dorsal MM mass become anterior and lateral leg compartments/ dorsum of foot (extensors and abductors)

Front 76

Postaxial MM, from what MM mass, have what action at ankle, STJ, toes?

Back 76

Dorsiflexion
Inversion or eversion
Extension

Front 77

INTERMISSION

Back 77

Take a sip, take a deuce, say a prayer, tie a noose. Now back for another round.

Front 78

what do posterior primary rami innervate?

Back 78

True back MM and dermis of the back.

Front 79

During development of LE the Neural tube contributes what?

Back 79

Neural tube- Spinal cord- alpha motor neurons- Anterior Roots (exiting to LE)

Front 80

Describe the formation of initial spinal N during LE development

Back 80

Migrating axonal processes from motor neurons in the developing anterior horns of the spinal cord and the peripheral processes of sensory neurons located in the developing posterior root ganglia will join to form the initial spinal nerves.

Front 81

During dvelopment of LE the Neural Crest contributes what?

Back 81

(Not neural tube) PRG cells (sensory aspect) to form posterior horns, Schwann cells that myelinate PNS, Satellite cells

Front 82

What happens after inital spinal N are formed in development of the LE?

Back 82

Spinal nerves split to form posterior and anterior primary rami.

Front 83

When do NN inervate the LE?

Back 83

As soon as the limb bud forms, anterior primary rami will penetrate into the limb bud mesenchyme where they will innervate the LE muscles and dermis.

Front 84

What rami innervates the LE?

Back 84

Anterior, Posterior goes to true back mm and overlying dermis

Front 85

What happens to each anterior primary rmaus as it enters the base of the LE limb bud?

Back 85

It splits into an anterior and posteiror dividsion

Front 86

The Anterior division from the anterior primary ramus innervate what?

Back 86

Anterior divisions innervate preaxial MM,
Flexor Compartments and adductors and the dermis and skin overlying the preaxial Muscles
So.. to add to the other mnemonic PreVee FAd

Ant-PreVee Fad
Anterior Division to Preaxial (Ventral MM mass) that does Flexion/adduction

Front 87

The posterior division from the anterior primary ramus innervate what?

Back 87

Posterior division to postaxial muscles that will form the extensor compartments and abductors and the dermis of the skin overlying postaxial Muscles

Front 88

What domain are the MM of the LE? therefore what rami innervate them?

Back 88

Abaxial domain (hypomere)
Anterior primary rami

Front 89

What happens as a result of rotation of LE to the myotome arrangement that was so orderly?

Back 89

An adult M is formed from more than one myotome and its inervation comes from more than one anterior primary ramus

Front 90

what naming difference is there from the brachial plexus to LE?

Back 90

No trunks.

Front 91

Explain the Mnemonic again:

Back 91

Ant-PreVe FAd
Anterior division innervates the Preaxial domain (ventral muscle mass) that are the Flexors/Adductors
All you need to know is one.

Front 92

Explain the naming of lumbar and sacral plexuses

Back 92

Anterior primary rami from I2-S3 that then divide into ant/posterior divisions, that then come together to named nerve (example sciatic is parts of anterior/posterior divisions of certain anterior rami)

Front 93

Nerves formed from posterior divisions of the anterior primary rami innervate what? What are the names?

Back 93

Femoral, common fib
Extensors and abductors and lateral rotators (postaxial) and dermatomes on extensor surface

Front 94

Nerves formed from anterior divisions of anterior primary rami innervate what? what are the names?

Back 94

Ant-PreVe FAd
innervate flexors/adductors and medial rotators and dermatomes on flexor surfaces
Obturator N
Tibial N (medial and lateral plantar brs)

Front 95

What is the Pink,
Purple?
Blue"

Back 95

Primaxial
Abaxial
Lateral somitic frontier
"Manifest destiny"

Front 96

What are these three items in the limb bud? Top to bottom

Back 96

Dorsal MM mass
Chondrification (hyaline from mesenchymal)
Ventral MM Mass
Ant-PreVe FAd

Front 97

Explain Limb bud axes

Back 97