Distal attachment

The terms proximal and distal attachments are used to describe the ends of limb muscles in relation to their position along the body’s longitudinal axis. These terms provide a clear, position-based alternative to origin and insertion, particularly useful in limbs where movement can occur in multiple directions.

• Proximal attachment: The site of attachment closer to the trunk or point of origin of the limb. It typically represents the fixed or less mobile end of the muscle during contraction. Example: In the biceps brachii, the proximal attachments are on the supraglenoid tubercle (long head) and coracoid process (short head) of the scapula.

• Distal attachment: The site of attachment farther from the trunk or point of origin of the limb. It is usually the more mobile end that moves toward the proximal attachment during contraction. Example: The distal attachment of the biceps brachii is on the radial tuberosity of the radius.

Summary

In limb muscles, contraction generally brings the distal attachment toward the proximal attachment, producing movement at the associated joint. For example, contraction of the biceps brachii flexes the forearm at the elbow as the distal radius moves toward the proximal scapula.