Rørknokler

Rørknokler are long bones found in the limbs of the body. They are characterized by their cylindrical shape and a hollow shaft called the diaphysis. The ends of the long bone are called epiphyses and are typically wider than the diaphysis. These bones play a crucial role in locomotion, providing support and leverage for movement.

The structure of a rørknogle is well-adapted for its function. The diaphysis is primarily composed of compact bone, which is dense and strong, providing structural integrity. The epiphyses are made up of spongy bone, which is lighter and contains red bone marrow responsible for producing blood cells. A layer of articular cartilage covers the surfaces of the epiphyses, reducing friction and allowing for smooth movement at the joints.

Rørknokler develop through a process called endochondral ossification. Initially, a cartilage model of the bone is formed. This cartilage is then gradually replaced by bone tissue, starting in the diaphysis and progressing towards the epiphyses. This process continues until skeletal maturity, when the growth plates located between the diaphysis and epiphyses fuse.

Examples of rørknokler include the femur (thigh bone), tibia and fibula (lower leg bones), humerus (upper arm bone), and radius and ulna (forearm bones). Their efficient design and arrangement allow for the complex movements required for walking, running, and manipulating objects. Damage to rørknokler, such as fractures, can significantly impair mobility.