human skeleton

The human skeleton is an internal framework composed of bones and cartilage that provides support, shape, and protection to the body. It plays several critical roles, including: 1. **Support**: The skeleton gives structure to the body and supports soft tissues and organs. 2. **Protection**: It encases vital organs, such as the brain (skull), heart and lungs (ribcage), and spinal cord (vertebral column). 3. **Movement**: Bones serve as levers and attachment points for muscles, enabling movement when muscles contract. 4. **Mineral Storage**: The skeleton stores essential minerals, primarily calcium and phosphorus, and releases them into the bloodstream as needed. 5. **Hematopoiesis**: Certain bones contain bone marrow, where the production of blood cells (red blood cells, white blood cells, and platelets) occurs. ### Composition of the Skeleton - **Bones**: The adult human skeleton comprises 206 bones, which can be categorized into two main groups: - **Axial Skeleton**: Includes the skull, vertebral column, and ribcage (80 bones). - **Appendicular Skeleton**: Comprises the bones of the limbs and the pelvic and shoulder girdles (126 bones). - **Cartilage**: A flexible connective tissue found in areas such as joints, the ribcage, and the nose, which cushions and supports. ### Major Bones of the Human Skeleton 1. **Skull**: Protects the brain and supports the structures of the face. 2. **Clavicle (collarbone)**: Connects the arm to the body. 3. **Scapula (shoulder blade)**: Provides attachment points for muscles. 4. **Sternum (breastbone)**: Part of the ribcage, protects the heart and lungs. 5. **Ribs**: Form the ribcage, protecting thoracic organs. 6. **Vertebrae**: Make up the spine, protecting the spinal cord and providing structural support. 7. **Pelvis**: Supports the weight of the upper body and protects pelvic organs. 8. **Femur (thigh bone)**: The longest bone in the body, involved in walking and running. 9. **Tibia and Fibula**: The two bones of the lower leg. 10. **Humerus**: The upper arm bone. ### Joints Bones are connected by joints, which can be classified into different types based on their range of motion: - **Fibrous Joints**: Fixed, such as the sutures in the skull. - **Cartilaginous Joints**: Slightly movable, such as the joints between vertebrae. - **Synovial Joints**: Freely movable joints, such as the knee and elbow, characterized by a fluid-filled joint capsule. Maintaining bone health is vital for overall health, requiring adequate nutrition (calcium and vitamin D), regular exercise, and avoiding factors like smoking and excessive alcohol consumption.