Hamill_ch05_137-186.qxd 11/2/07 3:55 PM Page 137 SECTION II Functional Anatomy CHAPTER 5 Functional Anatomy of the Upper Extremity CHAPTER 6 Functional Anatomy of the Lower Extremity CHAPTER 7 Functional Anatomy of the Trunk Hamill_ch05_137-186.qxd 11/2/07 3:55 PM Page 138 Hamill_ch05_137-186.qxd 11/2/07 3:55 PM Page 139 CHAPTER 5 Functional Anatomy of the Upper Extremity OBJECTIVES After reading this chapter, the student will be able to: 1. Describe the structure, support, and movements of the joints of the shoulder girdle, shoulder joint, elbow, wrist, and hand. 2. Describe the scapulohumeral rhythm in an arm movement. 3. Identify the muscular actions contributing to shoulder girdle, elbow, wrist, and hand movements. 4. Explain the differences in muscle strength across the different arm movements. 5. Identify common injuries to the shoulder, elbow, wrist, and hand. 6. Develop a set of strength and flexibility exercises for the upper extremity. 7. Identify the upper extremity muscular contributions to activities of daily living (e.g., rising from a chair), throwing, swimming, and swinging a golf club). 8. Describe some common wrist and hand positions used in precision or power. The Shoulder Complex Anatomical and Functional Characteristics Anatomical and Functional Characteristics of the Joints of the Wrist and Hand of the Joints of the Shoulder Combined Movements of the Wrist and Combined Movement Characteristics Hand of the Shoulder Complex Muscular Actions Muscular Actions Strength of the Hand and Fingers Strength of the Shoulder Muscles Conditioning Conditioning Injury Potential of the Hand and Fingers Injury Potential of the Shoulder Complex Contribution of Upper Extremity The Elbow and Radioulnar Joints Musculature to Sports Skills or Movements Anatomical and Functional Characteristics Overhand Throwing of the Joints of the Elbow The Golf Swing Muscular Actions External Forces and Moments Acting Strength of the Forearm Muscles at Joints in the Upper Extremity Conditioning Summary Injury Potential of the Forearm Review Questions The Wrist and Fingers 139 Hamill_ch05_137-186.qxd 11/2/07 3:55 PM Page 140 140 SECTION II Functional Anatomy he upper extremity is interesting from a functional Spine of scapula Tanatomy perspective because of the interplay among the various joints and segments necessary for smooth, effi- Supraspinous cient movement. Movements of the hand are made more fossa effective through proper hand positioning by the elbow, Acromion shoulder joint, and shoulder girdle. Also, forearm move- ments occur in concert with both hand and shoulder Coracoid movements (47). These movements would not be half as process effective if the movements occurred in isolation. Because of our heavy use of our arms and hands, the shoulder needs a high degree of structural protection and a high Shaft degree of functional control (4). Acromial end of clavicle Acromioclavicular The Shoulder Complex A joint The shoulder complex has many articulations, each con- tributing to the movement of the arm through coordi- Impression for Sternal end Acromial end costoclavicular ligament of clavical nated joint actions. Movement at the shoulder joint of clavicle involves a complex integration of static and dynamic sta- bilizers. There must be free motion and coordinated actions between all four joints: the scapulothoracic, ster- noclavicular, acromioclavicular, and glenohumeral Groove for joints (63,75). Although it is possible to create a small subclavius muscle amount of movement at any one of these articulations in Trapezoid line Conoid tubercle For first isolation, movement usually is generated at all of these costal cartilage joints concomitantly as the arm is raised or lowered or if B any other significant arm action is produced (88). Anterior sternoclavicular Interclavicular ANATOMICAL AND FUNCTIONAL ligament ligament CHARACTERISTICS OF THE JOINTS OF THE SHOULDER Sternoclavicular Joint The only point of skeletal attachment of the upper extremity to the trunk occurs at the sternoclavicular joint. Clavicle At this joint, the clavicle is joined to the manubrium of the sternum. The clavicle serves four roles by serving as a 1st rib site of muscular attachment, providing a barrier to protect underlying structures, acting as a strut to stabilize the Costoclavicular ligament shoulder and prevent medial displacement when the mus- Intra-articular cles contract, and preventing an inferior migration of the disk shoulder girdle (75). The large end of clavicle articulating Sternoclavicular joint capsule and anterior 2nd rib with a small surface on the sternum at the sternoclavicular ligament joint requires significant stability from the ligaments (75). A close view of the clavicle and the sternoclavicular joint is C shown in Figure 5-1. This gliding synovial joint has a FIGURE 5-1 The clavicle articulates with the acromion process on the fibrocartilaginous disc (89). The joint is reinforced by scapula to form the acromioclavicular joint (A). An S-shaped bone (B), the clavicle also articulates with the sternum to form the sternoclavicu- three ligaments: the interclavicular, costoclavicular, and lar joint (C). sternoclavicular ligaments, of which the costoclavicular ligament is the main support for the joint (73) (Fig. 5-2). The joint is also reinforced and supported by muscles, freedom. The clavicle can move superiorly and inferiorly such as the short, powerful subclavius. Additionally, a in movements referred to as elevation and depression, strong joint capsule contributes to making the joint respectively. These movements take place between the resilient to dislocation or disruption. clavicle and the meniscus in the sternoclavicular joint Movements of the clavicle at the sternoclavicular and have a range of motion of approximately 30° to joint occur in three directions, giving it three degrees of 40° (75,89). Hamill_ch05_137-186.qxd 11/2/07 3:55 PM Page 141 CHAPTER 5 Functional Anatomy of the Upper Extremity 141 Coracoclavicular Coracoclavicular ligament (conoid) ligament (trapezoid) Clavicle Coracoacromial ligament Acromioclavicular ligament Acromion Coracohumeral ligament Costoclavicular ligament Subscapular bursae Glenohumeral Anterior sternoclavicular ligament ligament Transverse humeral ligament Biceps brachii Subscapularis tendon A B Ligament Insertion Action Acromioclavicular Acromion process TO clavicle Prevents separation of clavicle and scapula; prevents posterior and anterior displacement Coracoacromial Coracoid process TO acromion process Forms arch over shoulder Coracoclavicular: Trapezoid, Base of coracoid process TO inferior Maintains relationship between scapula and clavicle; prevents conoid surface of clavicle anterior and posterior scapula movements; prevents upward and downward movements of clavicle on scapula Coracohumeral Base of lateral coracoid process TO Checks upward displacement of humeral head; checks external greater and lesser tuberosity rotation; prevents posterior glide of humeral head during flexion, on humerus adduction, and internal rotation; prevents inferior translation of humeral head during shoulder adduction Costoclavicular Upper surface of first rib to inferior Anterior fibers resist excessive upper rotation, and posterior fibers clavicle resist excessive downward rotation of clavicle; checks clavicle elevation and anterior, posterior, lateral movement Glenohumeral: Inferior, Upper anterior edge of glenoid TO Taut in external rotation and abduction; limits anterior middle, superior over, in front of, below humeral head translation of humerus Interclavicular Superomedial clavicle TO capsule Prevents superior and lateral displacement of clavicle on sternum; and upper sternum checks against excessive downward rotation of clavicle Sternoclavicular: anterior, Clavicle TO sternum Prevents anterior and posterior glide of clavicle posterior Transverse Across bicipital groove Keeps biceps tendon in groove FIGURE 5-2 Ligaments of the shoulder region. Anterior aspects of the sternum (A) and shoulder (B) are shown. The clavicle can also move anteriorly and posteriorly via similar to the sternoclavicular joint (73). At this joint, movements in the transverse plane termed protraction most of the movements of the scapula on the clavicle and retraction, respectively. These movements occur occur, and the joint handles large contact stresses as a between the sternum and the meniscus in the joint result of high axial loads that are transmitted through the through a range of motion of approximately 30° to 35° in joint (75). each direction (75). Finally, the clavicle can rotate anteri- The AC joint lies over the top of the humeral head orly and posteriorly along its long axis through approxi- and can serve as a bony restriction to arm movements mately 40° to 50° (75,89). above the head. The joint is reinforced with a dense cap- sule and a set of AC ligaments lying above and below the Acromioclavicular Joint joint (Fig. 5-2). The AC ligaments primarily support the The clavicle is connected to the scapula at its distal end via joint in low load and small movement situations. Close the acromioclavicular (AC) joint (Fig. 5-1). This is a small, to the AC joint is the important coracoclavicular liga- gliding synovial joint that is the size of 9 by 19 mm in ment, which assists scapular movements by serving as an adults (75) and it frequently has a fibrocartilaginous disc axis of rotation and by providing substantial support in Hamill_ch05_137-186.qxd 11/2/07 3:55 PM Page 142 142 SECTION II Functional Anatomy movements requiring more