The number of joints depends on if sesamoids are joint birthday cake ideas for adults, age of the human and the definition of joints. However, the number of sesamoids is the same in most people with variations being rare.

Joints are mainly classified structurally and functionally. Structural classification is determined by how the bones connect to each other, while functional classification is determined by the degree of movement between the articulating bones. In practice, there is significant overlap between the two types of classifications. Cartilaginous joint, Fibrous joint, and Synovial joint. Structural classification names and divides joints according to the type of binding tissue that connects the bones to each other. Joints can also be classified functionally according to the type and degree of movement they allow: Joint movements are described with reference to the basic anatomical planes.

Joints can also be classified based on their anatomy or on their biomechanical properties. Unmyelinated nerve fibers are abundant in joint capsules and ligaments as well as in the outer part of intraarticular menisci. These nerve fibers are responsible for pain perception when a joint is strained. Swimming is a great way to exercise the joints with minimal damage. A joint disorder is termed arthropathy, and when involving inflammation of one or more joints the disorder is called arthritis.

Most joint disorders involve arthritis, but joint damage by external physical trauma is typically not termed arthritis. Arthritis is the leading cause of disability in people over the age of 55. There are many different forms of arthritis, each of which has a different cause. The English word joint is a past participle of the verb join, and can be read as joined. Joint is derived from Latin iunctus, past participle of the Latin verb iungere, join, unite, connect, attach. The English term articulation is derived from Latin articulatio.