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6 Cards in this Set
- Front
- Back
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Definition of Ossification |
The process by which bone forms |
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Define the 2 different types of ossification |
Intramembranous - bone forms directly within the mesenchyme, which is arranged in sheer-like layers that resemble membranes Endochondral - bone forms within hyaline cartilage that develops from mesenchyme |
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List the steps on intramembranous ossification (4) |
1. Development of ossification center - mesenchymal cells cluster and differentiate 2. calcification - calcium and other mineral salts are deposited in the extracellular matrix and become calcified 3. Formation of trabeculae - extracellular matrix develops into trabeculae that fuses to spongy bone 4. Development of periosteum - mesenchume at periphery on bone condensed and forms the periosteum |
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List the steps of endochondral ossification (7) |
1. Initial condensation of mesenchyme 2. Growth of hyaline cartilage model 3. Osteoblasts lay down bony periosteal band 4. Fetal arteries penetrate diaphysial region of template, initiating ossification from the center (primary ossification) 5. Ossification spreads toward distal ends (development of medullary cavity) 6. Appearances of secondary ossification centers in distal ends 7. Ossification continues until only discrete epiphyseal plates remain cartilaginous (hyaline cartilage becomes articular cartilage) |
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Describe the 4 layers of the epiphyseal plate |
1. Zone of resting cartilage - nearest epiphysis, consists of small scattered chondrocytes 2. Zone of proliferating cartilage - slightly larger chondrocytes arranged like stacks of coins 3. Zone of Hypertrophic cartilage - large, maturing chondrocytes arranged in columns 4. Zone of Calcified Cartilage - a few cells thick, consisting of mainly dead chondrocytes surrounded by calcified extracellular matrix becoming the new diaphysis |
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Give examples of bones that form from intramembranous and endochondral ossification |
Intramembranous - Flat bones of the skull, most of the facial bones, mandible, and medial part of clavical Endochondral - femur, humerus, phalanges, etc. |
