Ch. 7.4 Skeletal System Key Terms
Appendicular Skeleton
The part of the skeleton that includes the bones of the limbs (upper and lower) and the girdles (pectoral and pelvic) that attach the limbs to the axial skeleton.
Axial Skeleton
The central part of the skeleton, consisting of the skull, vertebral column, and thoracic cage (ribs and sternum).
Skeletal System
The body system composed of bones, cartilages, ligaments, and tendons that provides support, protection, allows movement, and serves as a reservoir for minerals.
Joints
Also called articulations, these are the places where two or more bones meet. They are responsible for movement and stability.
Ligaments
Strong, fibrous connective tissue that connects bone to bone, primarily serving to support and strengthen joints.
Foramina
Openings, holes, or passages in a bone (or other structure), typically serving as a passageway for blood vessels and nerves.
Diaphysis
The shaft or central, long part of a long bone.
Epiphysis
The ends of a long bone, typically wider than the diaphysis, usually covered with articular cartilage.
Periosteum
A tough, fibrous membrane that covers the outer surface of a bone, except at the joint surfaces. It contains blood vessels, nerves, and bone-forming cells.
Endosteum
A thin vascular membrane that lines the inner surface of the medullary canal.
Medullary Canal
The hollow central cavity of the bone diaphysis (shaft), typically containing bone marrow.
Red Marrow
The type of bone marrow found in the epiphyses of long bones and in flat bones; it's responsible for hematopoiesis (production of red blood cells, white blood cells, and platelets).
Yellow Marrow
The type of bone marrow found in the medullary canal of long bones; it's primarily composed of fat cells and serves as a fat storage reserve.
Cranium
The part of the skull that encloses and protects the brain.
Fontanels
The "soft spots" on a baby's skull, which are areas of fibrous connective tissue where the skull bones haven't completely fused yet, allowing for brain growth and passage through the birth canal.
Sutures
Immovable, interlocking joints that connect the flat bones of the adult skull.
Sinuses
Air-filled, mucous membrane-lined cavities within certain bones of the skull (like the frontal, sphenoid, ethmoid, and maxillary bones). They lighten the skull and resonate.
Vertebrae
The bones that make up the backbone or spinal column, protecting the spinal cord and providing support.
Ribs
The curved bones that form the thoracic cage, protecting the heart and lungs. Humans typically have 12 pairs.
Sternum
The "breastbone," a flat bone located in the center of the chest to which the clavicles and most true ribs connect.
Clavicles
The "collarbones," two slender bones that connect the sternum to the scapulae, forming the anterior part of the pectoral girdle.
Scapulas
The "shoulder blades," two large, flat, triangular bones that form the posterior part of the pectoral girdle.
Humerus
The single long bone of the upper arm (brachium).
Radius
One of the two bones of the forearm (lower arm); it's on the thumb side and can rotate around the ulna.
Ulna
One of the two bones of the forearm (lower arm); it's on the pinky-finger side and is the primary bone forming the elbow joint.