Chapter 18: The Elbow and Forearm Complex

Introduction

A freely mobile but strong and stable elbow complex is required for normal upper extremity function. The design of the elbow and forearm adds to the mobility of the hand in space by shortening and lengthening the upper extremity and by rotating the forearm. The muscles provide control and stability to the region as the hand is used for various activities, from eating, dressing, and grooming to pushing, pulling, turning, lifting, throwing, catching, and reaching for objects to coordinated use of equipment, tools, and machines.^69,74,87 Most activities of daily living require a 100° arc of flexion and extension at the elbow, specifically between 30° and 130°, as well as 100° of forearm rotation, equally divided between pronation and supination.^69,74 Tasks such as drinking and eating primarily require elbow flexion, whereas a task such as throwing a ball and reaching to tie shoelaces requires substantial elbow extension.

Injury or disease of bony, articular, or soft tissue structures of the elbow and forearm can cause pain and compromised mobility, strength, stability, and functional use of the upper extremity. Loss of active or passive elbow flexion interferes with grooming and eating, whereas loss of elbow extension restricts a person’s ability to push up from a chair or reach for objects. In general, loss of terminal flexion of the elbow contributes to greater limitation of function than loss of terminal extension.^69,74

The anatomical and kinesiological relationships of the elbow and forearm are outlined in the first section of this chapter. Chapter 10 presents information on principles of soft tissue healing and management; the reader should be familiar with that material before establishing a therapeutic exercise program to improve function of the elbow and forearm.

Structure and Function of the Elbow and Forearm

The distal end of the humerus has two articular surfaces: the trochlea, which articulates with the ulna, and the capitulum, which articulates with the fovea of the head of the radius (Fig. 18.1). Flexion and extension occur between these two joint surfaces. The radius also articulates with the radial notch on the ulna at the proximal radioulnar joint (PRUJ). This joint contributes to pronation and supination along with the distal radioulnar joint (DRUJ). The capsule of the elbow encloses the humeroulnar (HU), humeroradial (HR), and proximal radioulnar (RU) articulations. The DRUJ is structurally separate from the elbow complex even though its function is directly related to the proximal radioulnar joint (PRUJ).⁷⁴

Joints of the Elbow and Forearm

There are four joints involved in elbow and forearm function: the HU, HR, proximal RU, and distal RU joints.

Elbow Joint Characteristics and ...