Chapter 6

At the conclusion of this chapter, the student should be able to:

• 1. Name, locate, and describe the structure and ligamentous reinforcements of the articulations of the elbow, forearm, wrist, and hand.
• 2. Name and demonstrate the movements possible in the joints of the elbow, forearm, wrist, and hand regardless of the starting position.
• 3. Name and locate the muscles and muscle groups of the elbow, forearm, wrist, and hand, and name their primary actions as agonists, stabilizers, neutralizers, or antagonists.
• 4. Analyze the fundamental movements of the forearm, hand, and fingers with respect to joint and muscle actions.
• 5. Describe the common athletic injuries of the forearm, elbow, wrist, and fingers.
• 6. Perform an anatomical analysis of the elbow, forearm, wrist, and hand in a motor skill.

In much the same way that the shoulder girdle’s cooperation with the shoulder joint contributes to the wide range of motion available to the hand, the cooperative movements of the elbow, radioulnar, and wrist joints contribute to the versatility and precision of its movements. Although the hand is intrinsically skillful, its usefulness is greatly impaired when anything interferes with the motions of the forearm or wrist. Injury to any one of the joints involved makes this painfully obvious to the sufferer.

### Structure

The elbow is far more complex than the simple hinge joint that it appears to be. The two bones of the forearm attach to the humerus in totally different ways. The humeroulnar joint is indeed a true hinge joint, but the humeroradial joint is far from it. It has been classified as an arthrodial or gliding type of joint, but it is more accurately described as a restricted ball-and-socket joint. Inspection of the articulating surfaces as depicted in Figure 6.1 or of the skeleton itself will help make this clear. The distal end of the humerus presents a spool-like process (trochlea) on the medial side and a spherical knob (capitulum) on the lateral side. The ulna articulates with the humerus by means of a semicircular structure that is cupped around the back and underside of the trochlea. The inner surface of this is known as the semilunar notch. It terminates below and in front in the small coronoid process, and above and in back in the broad olecranon process.

###### Figure 6.1

The bony structures of the elbow and radioulnar joints, anterior view.

The radius articulates with the humerus by means of a slightly concave, saucerlike disc, which is directly beneath the capitulum when the arm is hanging straight down. In spite of the joint’s ball-and-socket structure, the radius is unable to abduct or adduct because of the annular ligament that encircles the radial head and binds it to the radial notch of the ulna. Furthermore, because of this and other ligamentous connections with the ulna, ...

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