In anatomy, proximal and distal are directional terms used to describe the position of a structure with reference to its origin. Proximal means closer to the origin, while distal means further away. For example, in the upper limb, the origin is the shoulder, so the elbow is distal to the shoulder joint. In contrast, the wrist joint is distal to the elbow joint. Similarly, the thumb is distal to the wrist. Proximal and distal are often used to describe structures that are considered to have a beginning and an end, such as the upper limb, lower limb, and blood vessels. It is important to note that proximal and distal are opposite terms, with proximal indicating proximity and distal indicating distance.