Lecture 14 Osteogenesis and Joints

Question 1

Mineralization occurs via ____ ions.

Answer 1

Calcium

Question 2

Give some examples of bones that develop by intramembranous ossification.

Answer 2

Frontal
Parietal 
part of: 
  - occipital
  - temporal
  - mandible
  - maxilla

Question 3

What 3 things does intramembranous ossification require?

Answer 3

1) well-vascularized primitive connective tissue
2) bone formation is not preceded by the formation of a cartilage
3) an aggregate of mesenchymal cells differentiates directly into osteoid-producing osteoblasts

Question 4

True or False:

During intramembranous ossification bone formation is not preceded by the formation of a cartilage.

Answer 4

True

Question 5

To begin intramembranous bone formation, an aggregation of mesenchymal cells differentiate into what type of cell?

Answer 5

osteoblast

Question 6

Fill in the blank:

Osteoblasts secrete ____, trapping some of the osteoblasts (blastema).

Answer 6

osteoid

Question 7

During intramembranous bone formation osteoblasts secrete osteoid (which includes type I collagen & non-collagen proteins) which traps the osteoblasts (blastema). The trapped osteoblasts then turn into osteocytes, in which these osteocytes form what?

Answer 7

Osteocytes form a functional syncytium.

Question 8

What type of bone is formed during intramembranous ossification when numerous trabeculae fuse together?

Answer 8

Spongy Bone

Question 9

Membrane bone usually consists of two layers of compact bone that enclose a layer of what?

Answer 9

Spongy Bone

Question 10

During intramembranous ossification, what type of cells line the surface of the bone blastema?

Hint: this cell type is outlining the functional syncytium made by the interconnected cell processes of osteocytes.

Answer 10

Osteoblasts

Question 11

What cell type initiates the modeling of the primary bone tissue?

Answer 11

osteoclasts

Question 12

Fill in the Blank:

Although primary bone tissue formation begins as an ______ process, it soon becomes _________ growth.

Answer 12

interstitial process, it soon becomes appositional growth.

Question 13

At the surface of the osteoid, osteoblasts continue the appositional deposit of matrix. What are the two main components of this matrix?

Answer 13

Type I collagen & Non-collagenous Proteins

Question 14

True or False:

Calcification is a form of mineralization and is ossification.

Answer 14

False, calcification is a form of mineralization, but is not ossification.

Question 15

During endochondral bone formation, what is bone replacing?

Answer 15

Cartilage

Question 16

Where does the primary ossification center occur in the cartilage model?

Answer 16

In the future diaphysis.

Question 17

During endochondral bone formation the network of cartilage matrix is calcified by the deposition of calcium salts. Is this ossification?

Answer 17

NO, not ossification.

Question 18

What is happening in the vascular invasion zone?

Answer 18

Osteoblasts begin to deposit osteoid along the calcified cartilage.
The osteoid calcifies.

Question 19

How do osteoprogenitor cells, (which are derived from the perivascular mesenchyme) reach the primary ossification center and generate osteoblasts?

Answer 19

Vascular invasion zone - thus, osteoprogenitor cells travel into primary ossification center through the blood vessels.

Question 20

What is happening to the chondrocytes in the hypertrophic zone?

Answer 20

Chondrocytes become hypertrophic as the ossification front approaches.

Question 21

What is expressed in the proliferative zone?

Answer 21

proliferative chondrocytes start expressing Cbfa 1/Runx2 transcription factors.

Question 22

What cell type enlarges the bone marrow cavity?

Answer 22

Osteoclasts (osteoclasts “chase”)

Question 23

What is the definition of a joint?

Answer 23

A joint is where two bones come together.

Question 24

What are the two types of cartilaginous joints (amphiarthroses)?

Answer 24

1) symphysis

2) synchondrosis

Question 25

What is a cartilaginous joint?

Answer 25

A joint where bones are joined by hyaline or fibrocartilage.

Question 26

What type of cartilage joins a symphysis type cartilaginous joint? Also, give 2 examples of a symphysis type cartilaginous joint.

Answer 26

fibrocartilage - intervertebral discs and pubic symphysis

Question 27

What type of cartilage joins a synchondrosis type cartilaginous joint? Also, give 2 examples of a synchondroses type cartilaginous joint.

Answer 27

Hyaline cartilage - epiphyseal plates and the first sternocostal joint.

Question 28

What are the 3 sub-classes of fibrous joints (synarthroses)?

Answer 28

1) suture 2) gomphosis 3) syndesmosis

Question 29

What type of join is the fibrous joint (synarthroses)?

Answer 29

A join where bones are joined by collagenous and/or elastic fibrous connective tissue.

Question 30

Give an example of a suture type fibrous joint.

Answer 30

Examples are the joints between the bones of the calvaria.

Question 31

Give an example of a gomphosis type fibrous joint.

Answer 31

This is a "peg-in-the-socket joint such as the teeth in the alveoli.

Question 32

Give an example of a syndesmosis type fibrous joint.

Answer 32

Bones are joined by an interosseous fibrous membrane such as the fibrous membrane between the tibia and fibula.

Question 33

What are the 3 types of synovial joints (diarthroses)?

Answer 33

1) monaxial 2) biaxial 3) triaxial

Question 34

What is a synovial joint (diarthroses)?

Answer 34

These are the movable joints exemplified by a connective capsule surrounding a fluid-filled joint space.

Question 35

What are the two functions that ligaments play with a synovial joint?

Answer 35

Ligaments stabilize the capsule and the joint, as well as control and restrict direction and range of motion.

Question 36

What are the different types of synovial joints based on?

Answer 36

Based on degrees of freedom of movement.

Question 37

What are two different monaxial types of synovial joints and give an example of each?

Answer 37

Hinge Joint -> humeroulnar and knee joints Pivot Joints -> atlantoaxial and radioulnar joints

Question 38

Give 2 examples of a biaxial type synovial joint and examples found in the body.

Answer 38

Condyloid Joint -> metacarpophalangeal and atlantooccipital joints Saddle (sellaris) Joint -> first carpometacarpal joint

Question 39

Give an example of a triaxial type synovial joint and where it can be found in the body.

Answer 39

Ball-and-Socket Joint -> glenohumeral and femoroacetabular joints.

Question 40

In a synovial joint, is the inner synovial portion of the capsule vascularized? Is the outer fibrous portion of the capsule?

Answer 40

Yes, inner synovial portion of capsule is vascularized. No, outer fibrous portion of capsule is innervated but not vascularized.

Question 41

True or False: The synovial membrane has a basal lamina?

Answer 41

False, The synovial membrane does not have a basal lamina.

Question 42

How many layers of synovial cells make up the synovial membrane?

Answer 42

1-3 layers of synovial cells.

Question 43

What type of cartilage makes up articular cartilage? Does it have a perichondrium? And is it lined by a synovial membrane?

Answer 43

Hyaline Cartilage Lacks a perichondrium Not lined by a synovial membrane

Question 44

Is the joint capsule of a synovial joint vascularized by dense connective tissue, lined by synovial membrane, and attached to edges of articular cartilage?

Answer 44

Yes, vascularized dense connective tissue Yes, lined by synovial membrane Yes, attached to edges of articular cartilage

Question 45

What hyaluronic acid-protein complex does synovial cells produce?

Answer 45

mucin, which is in synovial fluid. ** mucin produces slick surface that is more slick than ice on ice.

Question 46

What are the 2 types of synovial cells?

Answer 46

type A -> macrophage-like type B -> fibroblast-like