Skeletal System Quiz

The skeletal system performs several crucial roles, including supporting the body, protecting vital organs, enabling movement, storing minerals (like calcium), and producing blood cells in the bone marrow.

A long bone, like the femur (thigh bone), has distinct sections: the diaphysis (shaft), epiphyses (ends), articular cartilage (smooth covering), periosteum (outer membrane), medullary cavity (hollow center), and endosteum (inner membrane).

Compact bone is dense and solid, forming the outer layer of most bones, providing strength. Spongy bone is lighter and porous, found mainly at the ends of long bones, providing flexibility. Both contain osteocytes (bone cells) but are structured differently.

Osteoblasts build new bone tissue, osteocytes maintain bone structure, and osteoclasts break down old bone tissue. These cells work together to remodel and repair bones.

During development, bones begin as cartilage models that are replaced by bone tissue. This process involves osteoblasts depositing calcium phosphate, forming strong mineralized bone.

Bones are constantly being remodeled, with osteoclasts breaking down old bone and osteoblasts building new bone. Hormones like parathyroid hormone (PTH) and calcitonin regulate this process to maintain calcium levels in the blood.

The axial skeleton (skull, vertebral column, rib cage) provides support and protection. The appendicular skeleton (limbs, shoulder girdle, pelvic girdle) enables movement and locomotion.

Joints are connections between bones, categorized as fibrous (immovable), cartilaginous (slightly movable), and synovial (freely movable). Synovial joints have a joint capsule, synovial fluid, and ligaments.

Synovial joints are classified by their shape and movement: ball-and-socket (wide range), hinge (one plane), pivot (rotation), gliding (sliding), condyloid (oval movement), saddle (two axes).

Bones have unique features like projections (for muscle attachment), depressions (for blood vessels), and openings (for nerves). These markings indicate function and aid in identification.