Skip to Main Content


After completing this chapter, you will be able to:

  • Explain how anatomical structure affects movement capabilities of ­upper-extremity articulations.

  • Identify factors influencing the relative mobility and stability of ­upper-­extremity articulations.

  • Identify muscles that are active during specific upper-extremity ­movements.

  • Describe the biomechanical contributions to common injuries of the ­upper extremity.


Log on to Connect for access to these additional resources:

  • Online Lab Manual

  • Chapter lecture PowerPoint presentation

  • Chapter quizzes

  • Additional chapter resources

  • Web links for study and exploration of chapter-related topics

©Vaara/Getty Images

The capabilities of the upper extremity are varied and impressive. With the same basic anatomical structure of the arm, forearm, hand, and fingers, major league baseball pitchers hurl fastballs at 40 m/s, swimmers cross the English Channel, gymnasts perform the iron cross, travelers carry briefcases, seamstresses thread needles, and students text on smartphones. This chapter reviews the anatomical structures enabling these different types of movement and examines the ways in which the muscles cooperate to achieve the diversity of movement of which the upper extremity is capable.

Pitching a ball requires the coordination of the muscles of the entire upper extremity. ©Susan Hall


The shoulder is the most complex joint in the human body, largely because it includes five separate articulations: the glenohumeral joint, the sternoclavicular joint, the acromioclavicular joint, the coracoclavicular joint, and the scapulothoracic joint. The glenohumeral joint is the articulation between the head of the humerus and the glenoid fossa of the scapula, which is the ball-and-socket joint typically considered to be the major shoulder joint. The sternoclavicular and acromioclavicular joints ­provide mobility for the clavicle and the scapula—the bones of the shoulder girdle.

The glenohumeral joint is considered to be the shoulder joint.

Sternoclavicular Joint

The proximal end of the clavicle articulates with the clavicular notch of the ­manubrium of the sternum and with the cartilage of the first rib to form the ­sternoclavicular joint. This joint provides the major axis of rotation for movements of the clavicle and scapula (Figure 7-1). The sternoclavicular (SC) joint is a ­modified ball and socket, with 35° of frontal plane motion and 70° of transverse plane motion ­permitted and some forward and backward sagittal plane rotation allowed (15). ­Although a fibrocartilaginous articular disc improves the fit of the articulating bone surfaces and serves as a shock absorber, joint stability is provided primarily by the posterior capsular ligament (15). Rotation occurs at the SC joint during motions such as shrugging the shoulders, elevating the arms above the head, and swimming. The close-packed position for the SC joint occurs with maximal shoulder elevation.


The sternoclavicular joint.


Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.