Abduction involves the 2 : 1 ratio of glenohumeral abduction to scapular upward rotation—the scapulohumeral rhythm. Box 4-1 summarizes the interactions among the joints during common shoulder motions. Muscle and Joint Interaction Y-T-W Drills. The glenohumeral (GH) joint is created by the articulation of the humeral head with the glenoid fossa of the scapula (Figure 4-12). Discuss basic movement patterns of the shoulder complex … When the arm is at rest, near the side of the body, the head of the humerus is held flush against the glenoid fossa, in part by the static locking mechanism of the glenohumeral (GH) joint. Many people with shoulder pain, weakness, and instability often need to focus on improvements in their scapular function to help improve their shoulder mechanics. The lesser tubercle is a sharp, anterior projection of bone just below the humeral head. The sternoclavicular (SC) joint is created by the articulation of the medial aspect of the clavicle with the sternum (Figure 4-6). All together they help hold your upper arm in place in the shoulder … Therapists often request that their patients perform shoulder exercises in the scapular plane as a way to prevent recurring impingement. Patients with Bankart lesions typically complain of significant shoulder instability, or feel as if the shoulder could “pop out” during various activities. The arthrokinematics of GH joint adduction is the same as that of shoulder abduction but in the reverse direction. Identify the bones and primary bony features relevant to the shoulder complex. Although the components of the shoulder complex constitute half of the mass of the entire upper limb,1 they are connected to the axial skeleton by a single joint, the sternoclavicular (SC) joint. Sternum • Describe the planes of motion and axes of rotation for the primary motions of the shoulder. As illustrated in Figure 4-17, B, when the scapula becomes downwardly rotated, as commonly occurs after a stroke involving weakness or paralysis of the trapezius muscles, the static locking mechanism becomes ineffective. First, it deepens the socket of the shallow glenoid fossa, improving the “fit” of the joint. The primary stabilizing force of this joint is garnered from the surrounding musculature, particularly the rotator cuff muscles. C, Upward and downward rotation. This will improve shoulder position and posture over time, which will ultimately lead to better function of the shoulder complex and can improve total kinetic chain movement. Second, approximately 50% of the fibers of the long head of the biceps tendon are direct extensions of the superior glenoid labrum. Scapulothoracic Joint Commonly called the shoulder blade, the scapula is a highly mobile, triangular bone that rests on the posterior side of the thorax (Figure 4-4). Much of the stability in the shoulder complex is … The entire upper extremity receives innervation primarily through the brachial plexus (Figure 4-18). The glenoid fossa is the slightly concave, oval-shaped surface that accepts the head of the humerus, composing the glenohumeral joint. Sternoclavicular, scapulothoracic, acromioclavicular, and glenohumeral. The SC joint structure is a saddle joint with concave and convex surfaces on each of the joint’s articular surfaces (Figure 4-7). The glenohumeral (GH) joint is a true synovial ball-and-socket style diarthrodial joint that is responsible for connecting the upper extremity to the trunk. • Interclavicular Ligament: Spans the jugular notch, connecting the superior medial aspects of the clavicles (From Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby, Figure 5-5.) Figure 4-10 illustrates the supporting structures of the AC joint. She finished treatment 4 months ago. The cords eventually branch into nerves that primarily innervate muscles of the upper extremity. The 60 degrees of scapular upward rotation and 120 degrees of glenohumeral (GH) joint abduction are shaded in purple. scapulohumeral rhythm ), (From Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby, Figure 5-13.  Clinical insight Normally, the GH joint allows approximately 120 degrees of abduction; the full 180 degrees of shoulder abduction normally occurs by combining 60 degrees of scapular upward rotation with the abduction of the GH joint. The proximal attachments of surrounding muscles are shown in red. The humerus is a long bone that forms the articulations of the glenohumeral joint proximally (with the scapula), and the humeral ulnar joint and humeral radial joint Objective: Movements of the human shoulder represent the result of a complex dynamic interplay of structural bony anatomy and biomechanics, static ligamentous and tendinous restraints, and dynamic muscle forces. The Superior shoulder suspensory complex(SSSC) is, essentially, a bone and soft-tissue ring secured to the trunk by superior and inferior bony struts from which the upper extremity is suspended. • Coracoclavicular Ligament: Composed of the conoid and trapezoid ligaments. Recall that the glenoid fossa is relatively flat and shallow, whereas the humeral head is large and round, making the anatomy of this joint more like a golf ball sitting on a quarter than like a ball-and-socket joint. Arthroplasty is a surgical procedure to restore the function of a joint by replacing disease and damaged parts. downward rotation Chapter 4 The static locking mechanism of the glenohumeral joint. 2011;46(4):349-357. The static locking mechanism helps provide stability to this loose-fitting joint. The 60 degrees of scapular upward rotation and 120 degrees of glenohumeral (GH) joint abduction are shaded in purple. The primary motions of this joint are abduction and adduction, flexion and extension, and internal and external rotation (Figure 4-13). Joint Structure and Function: A Comprehensive Analysis, 5e. The scapular upward rotation is depicted as a summation of 25 degrees of elevation at the sternoclavicular (SC) joint and 35 degrees of upward rotation at the acromioclavicular (AC) joint. Nerves of the Shoulder. Box 4-1 summarizes the interactions among the joints during common shoulder motions. Figure 4-17 The static locking mechanism of the glenohumeral joint. These relatively slight but important adjustment motions help to fine-tune the movements between the scapula and the humerus. The scapular spine divides the posterior aspect of the scapula into the supraspinatous fossa (above) and the infraspinatous fossa (below). First, the superior portion of the labrum is only loosely attached to the adjacent glenoid rim. 7. The labrum performs this important function in two ways. More distally, on the lateral aspect of the upper one third of the shaft of the humerus is the deltoid tuberosity—the distal insertion of all three heads of the deltoid muscle. The labrum serves to deepen the socket of the GH joint, nearly doubling the functional depth of the glenoid fossa. The superior capsular ligaments provide an upward force vector to counteract the downward force of gravity. The radial (spiral) groove runs obliquely across the posterior surface of the humerus. • Protraction of the scapula This conformation allows the clavicle to move in all three planes. The contradictory requirements on the shoulder complex for both mobility and stability are met through active forces, or dynamic stabilization, a concept of which the shoulder complex is considered a classic example. The shoulder complex functions through the interactions of which four joints? More distally, on the lateral aspect of the upper one third of the shaft of the humerus is the deltoid tuberosity—the distal insertion of all three heads of the deltoid muscle. Most often, this type of injury results in a SLAP lesion (Superior Labrum from Anterior to Posterior), which involves the superior aspect of the labrum. Rarely does a single muscle act in isolation at the shoulder complex. The muscles of the shoulder complex, therefore, must work in a highly coordinated fashion. Figure 4-10 illustrates the supporting structures of the AC joint. The shoulder is a complex and flexible joint, making it vulnerable to damage. J Pediatr Orthop. Figure 4-2 An anterior view of the sternum with the left clavicle and ribs removed. This relatively loose capsule attaches between the rim of the glenoid fossa and the anatomic neck of the humerus (see Figure 4-12). The shoulder complex includes the movement of the scapula and clavicle to greater increase degrees of movement of the humerus. 120 degrees of glenohumeral joint abduction This is known as impingement and often results in damage to the supraspinatus muscle or the subacromial bursa, which becomes pinched between these two bony structures (Figure 4-14, B). The muscles in the shoulder aid in a wide range of movement and help protect and maintain the main shoulder joint, known as the glenohumeral joint. Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on Google+ (Opens in new window) • Coracohumeral Ligament: Attaches between the coracoid process and the anterior side of the greater tubercle. Active internal and external rotation at the shoulder is functionally linked with active pronation and supination of the forearm. Ideal posture of the scapula positions the glenoid fossa so that it is tilted about 5 degrees upward (Figure 4-17, A). • Describe the location and primary function of the ligaments that support the joints of the shoulder complex. Similar to abduction, the full 180 degrees of shoulder flexion is obtained by incorporating approximately 60 degrees of scapular upward rotation. • Explain the force-couple that occurs to produce upward rotation of the scapula. The glenohumeral (GH) joint, which links the humerus and scapula, has greater mobility than any other joint in the body. The glenohumeral joint or shoulder joint is a ball and socket type of synovial joint that permits a wide range of movements including flexion, extension, abduction, adduction, rotation (medial and lateral rotation), and circumduction. The study aimed to evaluate pain, shoulder-arm complex function, and scapular function in women who developed lymphedema after breast cancer surgery and to … Proximal attachments of muscles are shown in red, distal attachments in gray. The role of the scapula in athletic shoulder function. Second, approximately 50% of the fibers of the long head of the biceps tendon are direct extensions of the superior glenoid labrum. • Describe the interaction between the internal and external rotators of the shoulder during a throwing motion. Symptoms of SLAP lesions often involve pain with overhead activities and “clicking” or “popping” of the shoulder. • Long Head of the Biceps: The proximal portion of the tendon wraps around the superior aspect of the humeral head, attaching to the superior glenoid tubercle. Upward and Downward Rotation The scapulothoracic mechanism is described, including a review of scapular motion and the structure and function of the sternoclavicular and acromioclavicular joints. Range of motion. B, Loss of the upward force—indicated by the cut rope—allows the glenoid fossa to downwardly rotate with a resultant inferior slide of the humerus. Common causes of shoulder pain include injuries, general wear and tear… READ MORE Extremity in all three planes to damage are incorporated in this episode of eOrthopodTV, surgeon. Glenoid labrum: a fibrocartilaginous ring of connective tissue that increases the,. 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