Skeletal System (Introduction)

Osteogenic, Osteoblast, Osteocytes, and Osteoclast

Cells

Intramembranous and Endochondral

Development

Compact and Spongy

Anatomy (Structure)

Epiphysis, Metaphysis, and Diaphysis

Anatomy (Parts)

Long, Short, Flat, and Irregular

Classification (Shape)

Axial and Appendicular

Classification (Location)

Organic and Inorganic

Composition

Organic 30-40%

Tissue fibers, bone corpuscles, ground substance; toughness and elasticity of bones

Inorganic 40-50%

Hydroxyapatite crystalized calcium phosphate salts; hardness and brittleness of bones

Osteogenic cells

Stem cells

Osteoblasts

Matrix-synthesizing cell responsible for bone growth.

Osteocytes

Mature bone cell that monitors and maintains the mineralized bone matrix.

Osteoclasts

Bone-resorbing cell

Bone remodeling

A process mediated by both osteoblasts and osteoclasts.

Intramembranous

Fibrous sheath similar to dermis of skin differentiates into osteoblast, mostly flat bones of skull, clavicle, and mandible.

Endochondral

Pre-existing model of hyaline cartilage, mostly vertebra, ribs, sternum, scapula, and pelvis.

Epiphysis

The expanded ends of a long bone which articulates with other bones to form joints and is primary site for red marrow in adults.

Metaphysis

The region between the epiphysis and the diaphysis which contains the epiphyseal plate in children and adolescents.

Diaphysis

The long central part of the long bone which houses the medullary cavity, which contains the yellow bone marrow.

Epiphyseal plate

It is located in the metaphysis of a long bone which is a layer of hyaline cartilage.

Endochondral ossification

Involves the replacement of hyaline cartilage with bone.

Long bones

Longer than they are wide; humerus, radius, ulna, metacarpal, phalanges, metatarsal, femurs, fibula, and tibia

Short bones

Cuboidal in shape; tarsals and carpals

Flat bones

Two thin plates of compact bone enclosing a layer of spongy bone.; sternum, cranial bones, scapulae, and ribs

Irregular bones

Bones without definite shape; vertebrae and sacrum