Lecture 11 - Osteogenesis and Joints Flashcards
Describe intramembranous bone formation.
- MESENCHYMAL cells DIFFERENTIATE into osteoblasts
- osteoblasts secrete OSTEOID contains, COLLAGEN I and non-collagenous fibers
- some become trapped forming BLASTEMA, differentiate into OSTEOCYTES
- mineralization occurs with Ca++
- primary ossification centers become TRABECULAE
- trabeculae fuse to form SPONGY BONE
Describe endochondral bone formation from the primary ossification center.
- primary ossification center occurs diaphysis of cartilage model
- chondrocytes become hypertrophic
- chondrocytes secrete vascular endothelial growth factor
- vascular bud forms and brings osteoprogenitor cells
- hypertrophic cartilage undergoes apoptosis, strands of calcified matrix is left behind
- osteoid is deposited on calcified matrix
- osteoid is calcified (ossification)
How is the periosteum formed?
-during the formation of primary ossification center, perichondrium secretes osteoid and is now periosteum
Where do secondary ossification centers occur?
-in the epiphyses
What separates the diaphysis and epiphyses?
-epiphyseal plates (growth plates)
What are the major zones in the epiphyseal plate and what occurs in each zone?
Reserve zone:
-hyaline cartilage responsible
Proliferation zone:
-chondrocytes align in columns
Hypertrophic zone:
-chondrocytes undergo apoptosis and matrix is calcified
Vascular invasion zone:
-penetration of blood vessels and introduction of osteoprogenitor cells
What is an amphiarthrosis and what are the different types?
Cartilagenous joints (hyaline or fibrocartilage
- symphysis: fibrocartilage (pubic symphysis and intervertebral discs)
- synchondrosis: hyaline cartilage (epiphyseal plates and sternocostal joint)
What is a synarthrosis joint and what are the types?
Fibrous joint
- suture: between bones of he calveria
- gomphosis: between teeth and alveoli
- syndesmosis: interosseous membranes
What are diarthrosis joints and what are the types?
Synovial joints
Monoaxial
- hinge (humeroulnar and knee)
- pivot (atlantoaxial and radioulnar)
Biaxial
- condyloid (metacarpophalangeal and atlantooccipital)
- saddle (first carpometacarpal)
Triaxial
-ball and socket (glenohumeral and femoroacetabular)
What are the different components of synovial joints? (5)
- articular cartilage
- joint capsule
- synovial membrane
- synovial fluid
- synovial cells
What are characteristics of the articular cartilage in synovial joints?
- hyaline cartilage
- lacks perichondrium (does not heal)
What are characteristics of the joint capsule in synovial joints?
- dense CT
- vascularized
- lined by synovial membrane
- attaches to edges of articular cartilage
What are characteristics of the synovial membrane in synovial joints?
- 1-3 layers of synovial cells
- highly vascularized (fenestrated capillaries = leaky)
- no basal lamina
What are characteristics of the synovial fluids in synovial joints?
- contains mucin (hyaluronic acid-protein complex)
- produced by synovial cells
What are the types of synovial cells in synovial joints?
- type A: macrophage-like
- type B: fibroblast-like
