The Anatomy Of The Tricep Muscles

The muscle on the back of your upper arm is called triceps brachii. The triceps comprises two-thirds of your upper-arm mass, so if you want more eye-catching arms, you have to dedicate at least as much effort to your triceps as to your biceps. But the key to triceps development is lifting really, really heavy weights. When well-defined, it forms a horseshoe-like shape.
The triceps brachii is the major upper arm muscle involved in elbow extenstion. The triceps is the only muscle that straightens the elbow joint, whereas three muscles (biceps, brachialis, and brachioradialis) bend the elbow.
Its primary function is to extend the forearm, and its secondary function is to draw the arm down and past the sides of the body. Knowing these functions, it is relatively easy to select the exercises best suited for stimulating growth in these muscles.
Located on the back of the upper arm, it is divided into three section, or “heads”:
- The lateral (outer) head
- The medial (middle) head
- The long (inner) head
The lateral head is on the outside rear of your upper arm and forms half of the horseshoe shape you see in a well-developed arm. The other half of that curve is formed by the triceps long head, on the inside-rear upper arm. The medial head is the thick part below the lateral head and above the elbow. All three heads come together in a tendon that is attached to the ulna.

For the triceps, the best are dips with the elbows close to the body, cable push-downs, bench dips, and dumbbell kickbacks.
Your triceps protect your elbow joints by acting as shock absorbers, lessening stress whenever your elbows are forced to flex suddenly, such as in breaking your fall in football or bracing yourself when mountain biking.
Signs of triceps weakness
- The most noticeable sign of triceps weakness is the inability to completely straighten your elbows in the bench press. If your sticking point is halfway up or above, it’s time to hit your triceps hard.
- An elbows-out style of benching, with the upper arms perpendicular to the body, is also an indication that the triceps are weak. Great benchers are usually able to keep their upper arms in closer to the body. Think of your arm position when trying to push open a heavy door.