Which muscle is primarily responsible for flexion of the elbow?

The biceps brachii is primarily responsible for flexion of the elbow due to its anatomical position and structure. It originates from the shoulder region and inserts at the radial tuberosity of the forearm. When the biceps brachii contracts, it pulls on the radius, causing the forearm to move towards the shoulder, thereby flexing the elbow joint.

While the biceps is the most well-known muscle for this action, the brachialis also plays a significant role in elbow flexion, effectively assisting the biceps during this movement. However, the biceps brachii is generally recognized as the primary flexor because of its dual role in supinating the forearm in addition to flexing the elbow. The triceps brachii, on the other hand, is primarily responsible for elbow extension, and the coracobrachialis is involved in flexion and adduction of the shoulder rather than the elbow. Thus, the distinct function and biomechanical advantage of the biceps brachii solidly establish it as the primary muscle for elbow flexion.