Dance Anatomy & Kinesiology

The Upper Extremity 419

Triceps Brachii

The triceps brachii (triceps, three heads + brachi, arm) is located superficially and makes up the muscle

mass of the back of the arm (figure 7.44A). As its name suggests, this muscle contains three heads—the

long, medial, and lateral heads. The long head arises proximally from just below the glenoid cavity of

the scapula. The lateral head arises proximally from the posterolateral upper half of the humerus. The

medial head originates from approximately the lower two-thirds of the posterior humerus. All three heads

join and then attach distally via a strong flat tendon to the olecranon process of the ulna. The triceps

is a powerful extensor of the elbow that is not influenced by pronation or supination of the forearm.

However, the long head of the triceps brachii crosses the shoulder and so is influenced by the position

of the shoulder. Its actions at the shoulder are extension and adduction. So, for example, performing

elbow extension with the arm behind the body, as in triceps kick back (table 7.10E, p. 436), will put

the long head at a disadvantage (length–tension principle) and provide greater overload.

FIGURE 7.44 Triceps brachii, supinator, and anconeus (right arm, posterior view). (A) Superficial view, (B) deeper view.

Palpation: Sit in a chair with the fingers of the left hand placed midway on the posterior aspect of

the right arm and the right palm resting on the right edge of the seat of the chair. The triceps brachii

can be felt contracting under your fingers when the right hand presses down on the seat of the chair

to lift the body (elbow extension).

Attachments and Primary Actions of Anconeus

Muscle Proximal attachment(s) Distal attachment(s) Primary action(s)

Anconeus

(an-KO-nee-us)

Posterior aspect of lateral

epicondyle of humerus

Lateral aspect of olecranon

process of ulna

Upper posterior ulna

Assists with elbow extension

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