Liðirnir

Liðirnir, or the joints, are the connections between bones that enable movement and provide stability across the skeleton. They vary in size, structure, and range of motion, from immovable sutures in the skull to highly mobile synovial joints in the limbs.

Structural classification places joints into three broad categories based on tissue type and movement: fibrous joints, which are connected by dense connective tissue and are mostly immovable or slightly movable; cartilaginous joints, which connect bones with cartilage and allow limited movement; and synovial joints, which are freely movable and feature a fluid-filled cavity.

Anatomy of a typical joint includes several key components. Articular cartilage covers the ends of the bones, reducing friction during movement. The joint capsule encases the joint, and the synovial membrane lines the capsule, producing synovial fluid that lubricates the joint. Supporting ligaments reinforce stability, while surrounding muscles and tendons contribute to movement and control.

Function and mechanics involve balancing mobility with stability. The shape of the articulating surfaces, the tension of ligaments, and muscle tone determine the joint’s range of motion and how loads are transmitted through the skeleton. Joints can be affected by injury or disease, limiting function or causing pain.

Development and medical relevance: Joints form during embryonic development and remodel as the body grows. Common conditions include osteoarthritis (degenerative joint disease), rheumatoid arthritis (autoimmune inflammatory disease), gout, dislocations, and sprains. Treatments range from physical therapy and medications to surgical interventions in severe cases.