Skeletal system
Skeletal System Components
- The skeletal system is comprised of bones, cartilage, ligaments, and other connective tissues.
- The body has approximately 206 bones, grouped into two main divisions: the axial skeleton and the appendicular skeleton.
- The axial skeleton includes the skull, vertebral column, and rib cage.
- The appendicular skeleton includes the limbs and girdles (shoulder bones and hip bones).
- Joint types range from immovable (e.g., skull sutures) to slightly movable (vertebral discs) and freely movable (elbow, knee).
Functions of the Skeletal System
- Support: The skeleton provides the structural frame to support the body's shape and maintains its posture.
- Protection: It shields vital organs, such as the brain, heart, and lungs.
- Movement: Bones act as levers with the help of muscles, enabling body movement.
- Mineral Storage: Bones store minerals like calcium and phosphorus which are essential for various cellular activities.
- Blood Cell Production: Bone marrow produces red and white blood cells in a process called haematopoiesis.
Bone Structure and Composition
- Bones are living tissues with a complex structure. They consist of a hard outer layer called compact bone and a spongy inner layer known as cancellous bone.
- Compact bone is dense, sturdy, and provides the bone its strength.
- Cancellous bone is lighter and contains trabeculae, which are small needle-like pieces of bone in a crisscross pattern with spaces for marrow.
- Bone marrow replenishes blood cells and is found within the cavities of certain bones.
- Bones are covered by a membrane called the periosteum, essential for nourishment, bone growth, and repair.
- The epiphysis and diaphysis are the ends and middle section of a long bone, respectively.
Bone Remodelling and Repair
- Bone remodelling is a lifelong process where old bone is replaced with new bone tissue.
- In response to stress or injury, the hard bone matrix is resorbed by osteoclasts, and new bone is formed by osteoblasts.
- Bone repair follows a series of steps starting from hematoma formation, fibrocartilaginous callus formation, bony callus formation, and finally bone remodelling.
Bone Categories
- Long bones (e.g., femur, tibia): Longer than they are wide and function as levers aiding in movement.
- Short bones (e.g., carpals, tarsals): Provide stability and support, less movement.
- Flat bones (e.g., skull, sternum): Protection of internal organs, muscle attachment.
- Irregular bones (e.g., vertebrae): Vary in shape and have multiple roles.
Remember, understanding the intricacies of the skeletal system can give you a better understanding of your body, improving both your training approach and injury-prevention strategies.