In this video we're gonna go over a very basic overview of the parts of a long bone. The diaphysis is the shaft of the bone and its function is to be rigid enough to tolerate strong forces and not bend or break. The diaphysis is comprised of compact bone tissue and spongy bone tissue. At each end of the diaphysis is an epiphysis, which is comprised mainly of spongy bone tissue. The spaces of spongy bone tissue contain red marrow, which produces red blood cells, white blood cells, and platelets. You can see at the epiphysis the bone widens out, this is so a joint can be formed with another bone. By the widening out of these bone ends, a larger surface area is created, providing for better joint stability. Where bones come together to form joints is a smooth tissue called articular cartilage. It provides shock absorption, cushioning, and minimizes friction as bones move. Because articular cartilage has a poor blood supply it does not heal very well once it's been damaged. There is a thin fibrous membrane called periosteum that covers the entire bone surface except where the articular cartilage is. This membrane allows for attachment of ligaments and muscle tendons, and houses cells that are important in bone formation and repairing bone tissue. The periosteum has many nerve fibers so it can be very painful when bruised. Inside the diaphysis is a tube-like area called the medullary cavity, which houses red marrow during childhood, and which is replaced by yellow marrow as a person ages. There is a thin membrane that lines the medullary cavity called the endosteum, which contains cells that are important in bone growth and repair. Bones are also well supplied with arteries and veins. And that be the basic parts of a long bone.