Chapter 24: The Forearm, Wrist, Hand, and Fingers

William E. Prentice

OBJECTIVES

When you finish this chapter you should be able to

• Review the structural and functional anatomy of the forearm, wrist, hand, and fingers.

• Outline the process of assessment for injuries to the forearm, wrist, hand, and fingers.

• Incorporate management techniques for dealing with injuries to the forearm, wrist, hand, and fingers.

• Implement the appropriate rehabilitation techniques for dealing with injuries to the forearm, wrist, hand, and fingers.

ANATOMY OF THE FOREARM

Bones

The bones of the forearm are the ulna and the radius (Figure 24–1). The ulna, which may be thought of as a direct extension of the humerus, is long, straight, and larger proximally than distally. The radius, considered an extension of the hand, is thicker distally than proximally.

Articulations

The forearm has three articulations: the superior, middle, and distal radioulnar joints. The superior radioulnar articulation is a pivot joint that moves in a ring formed by the ulna and the annular ligament.

The middle radioulnar joint, which is the junction between the shafts of the ulna and the radius, is held together by an oblique ligamentous cord and the interosseous membrane (Figure 24–1).⁴⁹ The oblique cord is a small band of ligamentous fibers that are attached to the lateral side of the ulna and pass downward and laterally to the radius. The interosseous membrane is a thin sheet of fibrous tissue that runs downward between the radius and the ulna and transmits forces directly through the hand from the radius to the ulna. The middle radioulnar joint provides a surface for muscle attachments, and there are openings for blood vessels at the upper and lower ends.

The distal radioulnar joint is a pivot joint formed by the articulation of the head of the ulna with a small notch on the radius.³¹ It is held securely by the anterior and posterior radioulnar ligaments. The inferior ends of the radius and ulna are bound by an articular, triangular disk that allows radial movement of 180 degrees into supination and pronation.

Forearm Musculature

The forearm muscles consist of flexors and pronators that are positioned anteriorly and extensors and supinators that lie posteriorly. The flexors of the wrist and fingers are separated into superficial muscles and deep muscles (Figure 24–2). The deep flexors arise from the ulna, the radius, and the interosseous tissue anteriorly, and the superficial flexors come from the internal humeral condyle. The extensors of the wrist and fingers originate on the posterior aspect and the external condyle of the ...