Skeletal and Muscular Systems: Joints, Movements and Muscles | Physical Education for A Level - Year 13 PDF Download

Skeletal System

• The skeletal system offers support, protection, mobility, mineral and lipid storage, blood cell formation, and energy storage.
• It comprises bones, cartilage, ligaments, and tendons.
• The human skeleton typically consists of 206 bones, divided into axial (80 bones) and appendicular (126 bones) categories.
• The axial skeleton includes the skull, vertebral column, ribs, and sternum, while the appendicular skeleton encompasses the limbs and pelvic girdle.
• Bones are classified as long (e.g., femur), short (e.g., carpals), flat (e.g., scapula), or irregular (e.g., vertebrae).

Joints

• A joint, or articulation, is the point where two bones connect.
• Joints vary in mobility and are functionally classified as synarthroses (immovable), amphiarthroses (slightly movable), or diarthroses (freely movable).
• Structurally, joints are categorized as fibrous (connected by dense connective tissue), cartilaginous (linked by cartilage), or synovial (not directly connected).
• Synovial joints are surrounded by a fibrous articular capsule lined with a synovial membrane and contain synovial fluid for lubrication. Types include hinge, pivot, saddle, plane, condyloid, and ball-and-socket joints.

Movements at Joints

• Flexion decreases the angle between articulating bones, while extension increases it.
• Abduction moves a structure away from the body’s midline, whereas adduction moves it toward the midline.
• Rotation involves a body part moving around its own axis, either internally (toward the body’s center) or externally (away from the center).
• Circumduction describes a circular movement of a body segment.
• Pronation rotates the forearm to face the palm downward, while supination rotates it to face upward.

Muscular System

• The muscular system facilitates movement, maintains posture, stabilizes joints, and produces heat.
• Muscles are divided into three types: skeletal, cardiac, and smooth.
• Skeletal muscles, which are voluntary, contract and relax to move bones, while cardiac and smooth muscles are involuntary.
• Muscles operate in pairs as agonists (primary movers) and antagonists (opposing muscles for balance).
• Key muscle components include muscle fibers, myofibrils, actin and myosin filaments, sarcoplasmic reticulum, and sarcolemma, all essential for muscle contraction.