Compact and Spongy Bone

University:
The University Of Western Ontario
Course:
ANAT 2200B | Systemic Anatomy of the Human Body
Academic year:

2022
Views:

381

Pages:

3
Author:

Kyuwon J.

● Spongy Bones ○ Cancellous Bone ■ Trabeculae ● thin bony plate, forms lattice structures ■ Marrow space ● located between trabeculae ○ Haemopoietic cells: blood cell precursors ○ Fat cells: yellow marrow ● used as strength support, reduced weight and support bone marrow ● Compact Bone ○ Dense solid structure in outer layer of bone ○ osteons (haversian system) ■ Central canal ● has blood vessels in nerves ■ Concentric lamellae ● rings on bone matrix surrounding canal ■ Osteocytes in lacunae ● live bone cells ● maintain bone matrix ■ Canaliculi ● small channels connecting osteocyte ● allows nutrient waste to be exchanged ■ Volkmann‘s channels ● transverse channels links adjacent osteons ● connects periosteum blood supply ■ Subperiosteal circumferential lamellae ● outer layer in periosteum will give structural strenght ● Blood supply ○ Nutrient artery ■ penetrate bone ■ supply nutrients to both spongy and compact bones ● Haversian canal (longitudinal supply) ● Volkmann‘s canal (transverse supply) ■ efficient delivery in oxygen and nutrients to osteocytes under mineralized matrix ■ Functions ● Spongy bones ○ support on light weight ○ shock absorptions ○ hematopoiesis ● Compact bones ○ strength ○ protection ○ resistance in bending ● allow bones for strong but light characteristics with functional movements Endochondral ossifications 1. Cartilage models a. hyaline cartilage will form the initial bone templates b. Chondroblasts producing cartilage matrix 2. 3. 4. 5. 6. c. surrounds periochondrium Early periosteum formations a. perichondirum differentiates to periosteum b. Osteoblasts shows up and builds up bone collar c. surrounds shaft(diaphysis) d. Collar will support the formation and restricts nutrient diffusions Development of bone collar a. chondrocytes hypertrophy i. cartilage matrix calcifies ii. death of chondrocytes in the center iii. space forms within cartilage Primary Ossifications Center (in shaft) Expansion of Ossifications a. bone trabeculae form in the marrow cavity b. periosteal bud will recruit osteoprogenitor cell, osteoclast, hematopoietic stem cells Secondary Ossification Center a. epiphyses i. end of bone b. gradually replaced with bone but… i. articular cartilage (in joints) ii. Epiphyseal plate (growth plates)