Final answer:
The rounded knob-like end separated from a bone by a neck is known as the 'head' of the bone, which typically articulates with other bones to form joints such as the hip or shoulder joint.
Step-by-step explanation:
The anatomical term that describes a rounded knob-like end separated from the rest of the bone by a slender region, the neck, typically refers to the head of a bone. This term is often used in the context of long bones, which have a head and a neck that facilitate articulation with other bones. For example, the head of the femur fits into the acetabulum of the hip bone to form the hip joint, while the head of the humerus articulates with the glenoid cavity of the scapula to form the shoulder joint. Similarly, the head of the radius articulates with the capitulum of the humerus as part of the elbow joint and with the radial notch of the ulna as part of the proximal radioulnar joint, while the neck of the radius is the narrowed region immediately distal to the head of the radius.
The neck of a bone refers to the slender region that separates the rounded knob-like end from the rest of the bone. In the context of the question, the neck being referred to is the neck of the radius. The radius is one of the two bones in the forearm, and its neck is the narrowed region immediately below the expanded head. It is important for the proper functioning of the radius and plays a role in the articulation of the bone with the humerus and ulna.