Answer
Parts of long bone and their functions
Work Step by Step
Parts of long bone
Proximal and distal epiphyses : the proximal and distal ends of the long bone
Diaphysis or shaft: the long cylindrical middle of the bone
Metaphysis: region of the bone between the epiphyses and the diaphysis
Contains the hyaline cartilage growth plate that allows the bone to grow in length;
the cartilage is replaced by bone at about age twelve – leaving a residual epiphyseal line
The epihyseal line: residue of hyaline cartilage growth plate of metaphysis
Articular cone; area of spongy bone with red bone marrow
Articular cartilage: layer of hyaline cartilage at point of articulation between bones of a joint
Functions: --reduces friction; absorbs shock – at freely movable joints
Lacks periosteum and blood vessels.
Periosteum: Layer of vascular connective tissue that surrounds the long bone in areas where articular
cartilage is absent. Three are two periosteal layers:
a. Fibrous layer : dense irregular connective tissue
b. Osteogenic layer of bone producing cells. These cells enable bones to grow thicker, but not longer
Functions of periosteum : affords physical protection; assists in repair of fractures; provides points of
attachment for ligaments and tendons; source of Sharpey’s fibers that penetrate extracellular
matrix and fastens periosteum to bone proper.
Medullary cavity: this is the hollow cylindrical space within the diaphysis. It contains yellow bone
marrow (in adults) and blood blood vessels. The hollow architecture provides maximal mechanical
strength with minimal weight.
Endosteum: the endosteum is the lining of the medullary cavity. It consists of connective tissue and a
single layer of osteogenic cells.
Nutrient arteries; arteries bring nourishment and oxygen into the marrow cavity.
