Skeletal System — Core Principles
Core Principles
The skeletal system is the body's internal framework, composed of bones, cartilage, ligaments, and tendons. It's broadly divided into the axial skeleton (skull, vertebral column, rib cage) for protection and central support, and the appendicular skeleton (limbs and girdles) for movement.
Bones provide structural support, protect vital organs, and act as levers for muscle action. They also store essential minerals like calcium and phosphorus, and house bone marrow for blood cell production (hematopoiesis).
Cartilage provides flexibility and cushioning in joints. Ligaments connect bones to bones, stabilizing joints, while tendons connect muscles to bones, facilitating movement. Joints, classified as fibrous (immovable), cartilaginous (slightly movable), or synovial (freely movable), dictate the range of motion.
Understanding the number and names of bones, types of joints, and common disorders like osteoporosis and arthritis is key for NEET.
Important Differences
vs Axial Skeleton vs. Appendicular Skeleton
| Aspect | This Topic | Axial Skeleton vs. Appendicular Skeleton |
|---|---|---|
| Composition | Skull, vertebral column, sternum, ribs (80 bones) | Pectoral and pelvic girdles, bones of upper and lower limbs (126 bones) |
| Primary Function | Protection of vital organs (brain, spinal cord, heart, lungs) and central body support | Locomotion, manipulation of objects, and attachment for muscles of movement |
| Mobility | Generally less mobile, providing stability | Generally more mobile, facilitating a wide range of movements |
| Examples of Bones | Cranium, vertebrae, sternum, true ribs | Humerus, femur, scapula, coxal bone |