The design of the shoulder girdle allows for mobility of the upper extremity. As a result, the hand can be placed almost anywhere within a sphere of movement, its range limited primarily by the length of the arm and the space taken up by the body. The combined mechanics of its joints and muscles provide for and control the mobility. When establishing a therapeutic exercise program for impaired function of the shoulder region, as with any other region of the body, the unique anatomical and kinesiological features must be taken into consideration as well as the state of pathology and functional limitations imposed by the impairments.
This chapter is divided into three major sections. The first section briefly reviews the structure and function of the shoulder girdle complex. The second section describes common disorders and guidelines for conservative and post-surgical management. The last section describes exercise techniques commonly used to meet the goals of treatment during the stages of tissue healing and phases of rehabilitation.
Structure and Function of the Shoulder Girdle
The shoulder girdle has only one boney attachment to the axial skeleton (Fig. 17.1). The clavicle articulates with the sternum via the small sternoclavicular joint. As a result, considerable mobility is allowed in the upper extremity. Stability is provided by an intricate balance between the scapular and glenohumeral muscles and the structures of the joints in the shoulder girdle.
Bones and joints of the shoulder girdle complex.
Joints of the Shoulder Girdle Complex
Three synovial joints (glenohumeral, acromioclavicular, sternoclavicular) and two functional articulations (scapulothoracic, suprahumeral) make up the shoulder girdle complex.
The glenohumeral (GH) joint is an incongruous, ball-and-socket (spheroidal) triaxial joint with a lax joint capsule. It is supported by the tendons of the rotator cuff and the glenohumeral (superior, middle, inferior) and coracohumeral ligaments (Fig. 17.2). The concave boney partner, the glenoid fossa, is located on the superior-lateral margin of the scapula. It faces anteriorly, laterally, and upward, which provides some stability to the joint. A fibrocartilagenous lip, the glenoid labrum, deepens the fossa for greater congruity and serves as the attachment site for the capsule. The convex boney partner is the head of the humerus. Only a small portion of the head comes in contact with the fossa at any one time, allowing for considerable humeral movement and potential instability.156
Ligaments of the glenohumeral (GH) and acromioclavicular (AC) joints.
According to the convex-concave theory of joint motion (see Chapter 5), with motions of the humerus ...