A&P Skeletal System Key Terminology Lecture A

axial skeleton

central skeleton; sternum, spine, skull

appendicular skeleton

extremities of the skeleton; arms and legs

Skeletal System

bones, joints, cartilages, and ligaments

Compact bone

homogeneous structure

Spongy Bone

Small needle-like pieces of bone. Very porous

Long Bones

Longer than they are wide. Have a shaft with heads at both ends. Contain mostly compact bone. Example femur and humerus

Short Bones

Generally cube-shaped. Contain mostly spongy bone. Example carpals and tarsals

Flat bones

Thin, flattened, and usually cured. Two thin layers of compact bone surround a layer of spongy bone. Examples skull, ribs, and sternum

Irregular bone

Irregular shape. Do not fit into other bone classification categories. Examples vertebrae and hip bones

Diaphysis

Shaft. Composed of compact bone

Epiphysis

Ends of the bone. Composed of mostly spongy bone

Periosteum

Outside covering of the diaphysis. Fibrous connective tissue membrane

Sharpey’s Fibers

Secure periosteum to underlying bone

Arteries

Supply bone cells with nutrients

Articular Cartilage

Covers the external surface of the epiphysis. Made of hyaline cartilage. Decreases friction at joint surfaces

Epiphyseal Plate

Flat plate of hyaline cartilage seen in young, growing bone

Epiphyseal Line

Remnant if the epiphyseal plate. Seen in adult bones

Medullary cavity

Cavity inside of the shaft. Contains either yellow or red marrow

Bone markings

Surface features of bones. Projections or processes. Depressions or cavities

Osteon (Haversian System)

A unit of bone containing central canal and matrix rings

Central (Haversian) Canal

Opening in the center of an osteon. Carries blood vessels and nerves

Perforating (Volkmans) Canal

Canal perpendicular to the central canal. Carries blood vessels and nerves

Lacunae

Cavities containing bone cells (osteocytes). Arranged in concentric ringsl

Lamellae

Rings around the central canal. Sites of lacunae

Canaliculi

Tiny canals. Radiate from central canal to lacunae. Form a transport system connecting all bone cells to a nutrient supply

Ossification

Bone growth

Bone remodeling

Performed by both osteoblasts and osteoclasts

Osteocytes

Mature bone cell

Osteoblast

Bone forming cell

Osteoclast

Bone destroying cell