Skeletal System Flashcards

Support, protection of organs, movement (with muscles), mineral storage (calcium/phosphorus), and blood cell production (hematopoiesis).

Long (femur), short (carpals), flat (sternum), and irregular (vertebrae). Some sources add sesamoid (patella).

Compact bone is dense, forming the outer shell (cortex) for strength. Spongy (cancellous) bone has a trabecular lattice, found at bone ends, housing red marrow.

The structural unit of compact bone: concentric lamellae of bone matrix surrounding a central (Haversian) canal containing blood vessels and nerves.

Osteoblasts build new bone matrix, osteocytes maintain bone tissue, and osteoclasts resorb (break down) bone.

A tough connective tissue membrane covering the outer surface of bone. It anchors tendons and ligaments and supplies blood for bone repair and growth.

A thin membrane lining the medullary cavity and trabecular surfaces of spongy bone. It contains osteoblasts and osteoclasts for remodeling.

Axial skeleton (80 bones): skull, vertebral column, ribs, sternum. Appendicular skeleton (126 bones): limbs, pectoral girdle, pelvic girdle.

Cervical 7, thoracic 12, lumbar 5, sacral 5 (fused), coccygeal 4 (fused). Total: 33 vertebrae, 26 individual bones.

A cartilage growth plate near the ends of long bones where longitudinal bone growth occurs. It ossifies into the epiphyseal line when growth is complete.

Hyaline (joint surfaces, trachea), elastic (ear, epiglottis), and fibrocartilage (intervertebral discs, menisci).

A thin layer of hyaline cartilage covering the ends of bones at synovial joints. It reduces friction and absorbs shock during movement.

Fibrous (sutures, no movement), cartilaginous (symphyses, limited movement), and synovial (freely movable, with a joint cavity).

Hinge (elbow), ball-and-socket (hip), pivot (atlas-axis), and condyloid (wrist). Others include saddle (thumb) and gliding (intercarpal).

Lubricates joint surfaces, reduces friction, nourishes articular cartilage, and absorbs shock within synovial joints.

A continuous process in which osteoclasts resorb old bone and osteoblasts deposit new bone, allowing the skeleton to adapt to stress and maintain calcium homeostasis.

Wolff's law states that bone remodels in response to mechanical stress, becoming thicker and stronger along lines of force.

Parathyroid hormone (stimulates osteoclasts, raises blood Ca2+), calcitonin (inhibits osteoclasts, lowers blood Ca2+), and growth hormone/sex hormones during development.

The hollow center of the diaphysis (shaft) of long bones. It contains yellow marrow (fat) in adults; red marrow fills it in children.

In the spongy bone of flat bones (sternum, pelvis, skull) and the proximal epiphyses of the humerus and femur. It produces blood cells.

Ligaments connect bone to bone, stabilizing joints. Tendons connect muscle to bone, transmitting force for movement.