STRUCTURES AND FUNCTIONS
The main functions of bone are support, protection of internal organs, voluntary
movement, blood cell production, and mineral storage.
Cylinder-shaped structural units (haversian systems) fit closely together in compact bone,
creating a dense bone structure.
Types of bone cells include osteoblasts, osteocytes, and osteoclasts.
o Osteoblasts synthesize organic bone matrix (collagen) and are the basic bone-
o Osteocytes are the mature bone cells.
o Osteoclasts participate in bone remodeling by assisting in the breakdown of bone
o Bone remodeling is removal of old bone by osteoclasts (resorption) and the
deposition of new bone by osteoblasts (ossification).
Each long bone consists of the epiphysis, diaphysis, and metaphysis.
o Epiphysis, the widened area found at end of a long bone, is composed of
cancellous bone. Epiphysis is the location of muscle attachment.
o Diaphysis is the main shaft of the bone. It provides structural support and is
composed of compact bone. Marrow is in the center.
o Metaphysis is the flared area of cancellous bone between the epiphysis and the
A joint (articulation) is where ends of two bones are in proximity and move in relation to
each other. Joints are classified according to degree of movement they allow.
Cartilage is a rigid connective tissue in synovial joints that serves as support for soft
tissue and provides articular surface for joint movement. Types of cartilage tissue include
hyaline, elastic, and fibrous.
Types of muscle tissue are cardiac (striated, involuntary), smooth (nonstriated,
involuntary), and skeletal (striated, voluntary) muscle.
A nerve fiber and the skeletal muscle fibers it stimulates are called a motor endplate. The
junction between axon of nerve cell and adjacent muscle cell is called the myoneural or
Ligaments and tendons are composed of dense, fibrous connective tissue. Tendons attach
muscles to bones, and ligaments connect bones to bones.
Fascia is defined as layers of connective tissue with intermeshed fibers that can
withstand limited stretching. Bursae are small sacs of connective tissue lined with synovial membrane and contain
Many functional problems experienced by the aging adult relate to changes of the
o Increased bone resorption an