The triceps brachii, or triceps, is a large muscle located on the back of your upper arm. This muscle extends nearly the entire length of the humerus, the bone of your upper arm. It contributes to the arm’s shape and function.
Anatomical Structure of the Triceps
The term “triceps” means “three heads,” describing its composition. It consists of three distinct parts: the long head, the lateral head, and the medial head. Each head originates from a different point before converging into a single tendon.
The long head of the triceps originates from the infraglenoid tubercle of the scapula, on the shoulder blade below the glenoid fossa. Its attachment also extends to the glenoid labrum and blends with the glenohumeral capsule of the shoulder joint. The lateral head arises from a narrow, linear ridge on the posterior surface of the humerus, positioned superior to the radial groove. A portion of its fibers also comes from the lateral intermuscular septum.
The medial head, often overlapped by the long and lateral heads, has a broad origin along the posterior surface of the humerus, inferior to the radial groove. All three muscle bellies then converge into a common, thick tendon that inserts onto the posterior aspect of the olecranon process of the ulna, the bony prominence of your elbow. This common tendon also attaches to the capsule of the elbow joint and the antebrachial fascia of the forearm.
Primary Functions of the Triceps
The triceps brachii is primarily responsible for extending the forearm at the elbow joint. This action straightens the arm, a movement essential for many daily activities like pushing objects or reaching. The triceps are active in pushing or thrusting motions, and when supporting body weight with partially flexed elbows, such as pushing oneself up from a chair.
The long head of the triceps has additional functions beyond elbow extension. Due to its origin on the scapula, it also contributes to the extension and adduction of the arm at the shoulder joint. It also helps stabilize the shoulder joint by holding the head of the humerus within the glenoid cavity. While the medial head is active in all forms of forearm extension, the long and lateral heads become more active when extension occurs against resistance.
Targeted Exercises for Triceps Development
To strengthen and develop the triceps, various exercises can be incorporated. These exercises often involve elbow extension and can emphasize different heads of the muscle. For instance, triceps pushdowns, typically using a cable machine, involve extending the arms downward from a high pulley, isolating the triceps. Keeping the elbows stationary and close to the sides helps focus the contraction.
Overhead triceps extensions, whether with dumbbells or cables, involve extending the arms overhead and lowering the weight behind the head. This movement targets the long head. Exercises like close-grip bench presses also work the triceps; a narrower grip emphasizes the triceps more than the chest. This variation places more load through the triceps, engaging all three heads.
Bodyweight exercises like dips are effective for triceps development. Lowering the body between parallel bars or using a bench engages the triceps. Keeping the elbows tucked close to the body and lowering until the upper arms are parallel to the floor helps maximize triceps engagement. Skullcrushers, or lying triceps extensions, involve lying on a bench and extending a barbell or dumbbells overhead, then bending the elbows to lower the weight towards the head. This exercise targets the triceps, requiring control to straighten the arms without locking the joints.