Dance Anatomy & Kinesiology

The Upper Extremity 421

TABLE 7.7 Movements of the Elbow and Radioulnar Joints and Key Muscles

That Can Produce Them

Joint movement Primary muscle(s) Secondary muscle(s)

Elbow flexion Biceps brachii

Brachialis

Brachioradialis

Pronator teres

Elbow extension Triceps brachii Anconeus

Radioulnar pronation Pronator quadratus Pronator teres

Brachioradialis (to midposition)

Radioulnar supination Supinator

Biceps brachii

Brachioradialis (to midposition)

Looking at the role of these muscles in movement on the simplest level, if the movement is performed
slowly and without a stylized quality, the following generalizations are germane. The elbow flexors—includ-
ing the brachialis and biceps brachii—are most commonly used concentrically (in an open kinematic
chain) to bring the forearm toward the upper arm against gravity such as when lifting something from
the ground (e.g., a partner) or against other external resistance such as a dumbbell (concentration
curl, table 7.10L, p. 441) or springs (kneeling biceps lift, table 7.10M, p. 442). The same elbow flexors
would then be used eccentrically to control the lowering of the forearm (elbow extension). However, when
the arm is fixed (closed kinematic chain), the elbow flexors can be used with the shoulder muscles to
help bring the torso closer to the arms in pulling motions, such as in a pull-up or in rope climbing. In
contrast, the elbow extensors—primarily the triceps brachii—can be used to straighten the elbow in
open kinematic chain movements such as in the tennis serve or in an overarm throw. Strengthening
exercises often incorporate elbow extension against external resistance, such as dumbbells (overhead
triceps extension, table 7.10N, p. 443) or a spring (kneeling triceps kick back, table 7.10O, p. 444).
When the hand is fixed, the elbow extensors are commonly used concentrically in closed kinematic
chain pushing movements such as a push-up (table 7.10A, p. 434) or raising the torso from a chair
(press-up, table 7.10C, p. 435) or the floor in dance. In dance, the elbow flexors and extensors are
also commonly used gesturally to shape the arms in accordance with choreographic intent.

Change in Relative Positioning

of the Distal Radius and Ulna With Pronation

Use the following exercise to demonstrate the influence of pronation and supination on the relative

positioning of the radius and ulna.

Palpate the ulna with the fingertips of your left hand by following the border of this bone on your

right arm from the olecranon down to the small projection at the wrist (styloid process). Keep the

elbow bent to 90° and by your side. Then, pronate the forearm while keeping the fingertips on the

styloid process, and note how the radius is now medial to the ulna, distally.

CONCEPT DEMONSTRATION 7.5

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