Musculoskeletal system

By Dr. Safa Ahmed Rheumatologist (MSc.) • It is the system that gives the humans the ability to move. • It provides them with support, protection and stability in addition to movement. • It is composed of bones, muscles, cartilage, tendons, ligaments and other connective tissues. • Adult human has 206 bones. • Classification of bones: there 5 types of bones: 1. Long bones: ex. Tibia, femur. 2. Short bones: tarsals and carpal bones. 3. Flat bones: scapula, ilium, skull bones. 4. Irregular bones: sphenoid bone, vertebrae, mandible. 5. Sesamoid bones: patella (largest sesamoid bone in body). The skeleton • It is divided into: 1. Axial skeleton: composed of the skull, vertebral column and rib cage. 2. Appendicular skeleton: shoulder girdle, pelvic girdle and the limbs (upper and lower). Function of the bones (skeleton)

• Provide attachment for tissues, organs and muscles. • Protection of vital organs. • Production of all RBCs, platelets and most of WBCs in adults (in the red marrow of long bones). • Fatty connective tissue in the yellow marrow of the long bones can be used as a source of energy during starvation. • Storage of minerals: mainly calcium and phosphorus (for when the body needs them). • There are 3 types of muscles: cardiac, smooth and skeletal muscles. • The skeletal muscles are the types that are attached to the bones of the skeleton and can move the body. • They are arranged in opposing groups around the joints. • They are innervated by nerves that conduct currents from the CNS to the muscle to contract. • A tough flexible band of connective tissue that connect the muscle to the bone. • The largest tendon in the body is the Achilles tendon • Joint (or articulation): is the connection between two bones in the body. • There are over 230 joints in the body • Joint functions: 1. Hold bones together. 2. Provide flexibility to allow movement occur. 3. Allow the growth of bones. Classification of joints

• Joints can be classified according to movement and tissue.

• MOVEMENT 1. Freely movable 2. Slightly movable 3. Immovable • TISSUE 1. Synovial 2. Fibrous 3. Cartilagenous • Synovial joint: most common and most movable kind of joints. It consists of 2 surfaces which are covered with cartilage and is surrounded by a synovial membrane and contains a synovial fluid which lubricates the joint.

• Cartilagenous joint: The 2 bones are connected entirely by cartilage, an example is the intervertebral discs. Slightly movable

• Fibrous joint: It has 3 types • -Suture: connect the bones of the skull. Non movable • -Syndesmosis: connect the ulna to radius and tibia to fibula, slightly movable. • -Gomphosis: Connect teeth to maxilla or mandible, non movable

Synovial joint types

• Ball and socket: ex. Shoulder, hip. • Condyloid: MCP joint. • Gliding: SIJ. • Pivot: radio-ulnar joint. • Hinge: elbow joint. • Saddle: joint at the base of the thumb.