Embryology of the Musculoskeletal and Integumentary Systems

Question 1

What week are the notochord and neural tube formed?

Answer 1

Week 3

Question 2

What forms the somites?

Answer 2

Paraxial mesoderm

Question 3

What do somites differentiate into?

Answer 3

Sclerotomes and dermatomes

Question 4

Where are the sclerotomes located are what do they form?

Answer 4

Located more central

Form vertebrae and ribs

Question 5

Where are the dermamyotomes located and what do they form?

Answer 5

More laterally

Muscles and dermis of skin

Question 6

At what day mark do scleratomes condense?

Answer 6

27 days (bone forming capacity)

Question 7

How many nerves innervate one vertebrae?

Answer 7

2 due to two scleratomes coming to together to form 1 disc

Question 8

What are the cranial sclerotomes made of?

Answer 8

Loose connective tissue

Question 9

What are the caudal sclerotomes made of?

Answer 9

Dense connective tissue

Question 10

How do sclerotomes shift?

Answer 10

The spinal nerves run through the scleratomes between the cranial and caudal portions; the cranial portion binds to the caudal portion above and the caudal portion binds to the cranial portion below

Question 11

What happens to the notochord?

Answer 11

It degenerates where the vertebrae form but stays in the nucleus pulposus

Question 12

What packs together to create balls of cartilage?

Answer 12

Mesoderm

Question 13

What are the balls of cartilage formed by the mesoderm called?

Answer 13

Chondrification centers

Question 14

Where are the primary ossification centers in the vertebrae?

Answer 14

One around the notochord

One on either side of the vertebral column

Question 15

Where is the neurocentral joint?

Answer 15

Joint between the vertebral body and the arch

Question 16

Which spinous processes ossify first?

Answer 16

Lumbar then cervical

Question 17

When does the development of limbs begin?

Answer 17

Near the end of week 4

Question 18

Where is the epaxial trunk located?

Answer 18

More dorsally

Question 19

Where is the hypaxial trunk located?

Answer 19

more anterior/ventrally

Question 20

What comes from the epaxial trunk?

Answer 20

Muscles that are superficial and go to the body wall (trapezius)

Question 21

What comes form the hypaxial trunk?

Answer 21

Muscles involved in flexion

Question 22

What type of ossification takes place in long bones?

Answer 22

Endochondral ossification

Question 23

What does endochondral ossification require to occur?

Answer 23

Cartilage model

Question 24

Where are the primary ossification centers in long bones?

Answer 24

At the end of the shaft

Question 25

What is the bone collar?

Answer 25

Forms around the periosteum; it serves to support the growing bone and allow vessels to go in (only around shaft not growth plate)

Question 26

What is the medullary cavity?

Answer 26

Cavity inside the bone that contains bone marrow

Question 27

When does ossification occur?

Answer 27

Before the end of the embryo stage (week 8)

Question 28

When does secondary ossification occur?

Answer 28

Around 2-3 years

Question 29

Which direction do ribs ossify?

Answer 29

Posteriorly to anteriorly

Question 30

Where do the upper limb buds come from?

Answer 30

Cervical somites

Question 31

Where do the lower limb buds come from?

Answer 31

Lumbar somites

Question 32

What is the apical ectodermal ridge?

Answer 32

Sends signals into mesenchyme to create zone of polarizing activity; essential for proper rotation of the limbs

Question 33

Which way do the upper limbs rotate?

Answer 33

90 degrees laterally

Question 34

Which way do the lower limbs rotate?

Answer 34

90 degrees medially

Question 35

What does the AER signal to create?

Answer 35

Digital rays in paddles

Question 36

Where does arterial blood supply for the limbs come from?

Answer 36

Dorsal aorta

Question 37

How do arteries grow with the growing limbs?

Answer 37

The dorsal aortic arteries are pulled with the growing limbs

Question 38

What are the branching arteries in adults called?

Answer 38

Primary axial arteries

Question 39

What is the absence of a limb called?

Answer 39

Amelia