The posterior deltoid is a shoulder muscle that, although small, is of great importance in training. The fibers run from the scapula to the humerus and are heavily involved in transverse extension.
Emphasizing this muscle when training will make all the difference. For one thing, the rear delts make the entire shoulder area appear rounder. In addition, they are vital for stabilizing the joint during weight lifting and when performing pulling movements.
What movements does the upper deltoid do?
The deltoid muscle is the main muscle of the glenohumeral (shoulder) joint and plays an important role in macroscopic movements of the arm. It consists of three muscle heads: the anterior deltoid, the lateral deltoid, and the posterior deltoid.
Function is motor, including shoulder abduction, flexion, and extension. This allows the joint to remain in its resting position, while you have the option of moving backward when necessary.
It is important to keep in mind that each head of the deltoid muscle plays a key role in stabilizing the glenohumeral joint, which serves to improve the smoothness and overall quality of arm movement:
- The anterior deltoid rotates the shoulder joint medially by pulling inward, allowing the arm to move forward (forward flexion).
- The lateral deltoid rotates the shoulder joint by laterally moving the arm outward (abduction). Abduction of the arm results in it moving away from the body, as if it were extended.
- The posterior deltoid rotates the joint laterally.