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shoulder complex function

All four joints must properly interact for normal shoulder motion to occur. All of the nerves that travel down the arm pass through the axilla (the armpit) just under the shoulder joint and are known as the Brachial Plexus before dividing into the individual nerves.These nerves carry the signals from the brain to the muscles that move the arm. It helps limit the extremes of external rotation, flexion, and extension, as well as inferior displacement of the humeral head (see Figure 4-12). (From Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby, Figure 5-39.) The arthrokinematics of abduction involves the convex head of the humerus rolling superiorly while simultaneously sliding inferiorly (Figure 4-14, A). “Put your shoulder to the wheel.” — Aesop + 60 degrees of scapulothoracic joint upward rotation Abduction and adduction of the GH joint occur in the frontal plane about an anterior-posterior axis of rotation, which courses through the humeral head. • Depression and retraction of the clavicle Clinicians therefore focus a great deal on evaluating and treating the quality and amount of motion between the scapula and the thorax. This means that for every 2 degrees of GH abduction, the scapula must simultaneously upwardly rotate roughly 1 degree.  Strong force-dissipating structures such as the SC disk and the costoclavicular ligament minimize articular stresses and also prevent excessive intra- articular motion that might lead to … This series of joints works together to provide large ranges of motion to the upper extremity in all three planes. • Flexion of the humerus This position not only improves the contact of the articulation but allows the surrounding soft tissues to help support this joint. General Features The shoulder is a complex and flexible joint, making it vulnerable to damage. 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) Movement away from the midline in the horizontal plane is considered horizontal abduction. Structure and Function of the Elbow and Forearm Complex, Structure and Function of the Ankle and Foot, Structure and Function of the Vertebral Column, Essentials of Kinesiology for the Physical Therapist Assistant. Scapular plane abduction is more natural than abduction in the pure frontal plane. Supporting Structures of the Acromioclavicular Joint. This type of injury often results from a traumatic anterior dislocation of the humerus. Related Motions of the right scapula against the posterior-lateral thorax. All motions are functionally linked to the motions that occur at the other three joints of the shoulder complex; these functional relationships are discussed in depth later. Acromioclavicular and Sternoclavicular Joint Interaction Within the Scapulohumeral Rhythm, Elevation and posterior rotation of the clavicle, Downward rotation and retraction of the scapula, Depression and retraction of the clavicle, Clavicular elevation and posterior rotation, Even with the humerus in full external rotation, complete abduction of the shoulder may result in impingement if performed in the true frontal plane (, A side view of the right glenohumeral joint comparing abduction of the humerus in the, Ideal posture of the scapula positions the glenoid fossa so that it is tilted about 5 degrees upward (. Kinematics Equally important, these motions allow the scapula to maintain firm contact with the posterior thorax. • Cite the normal ranges of motion for shoulder flexion and extension, abduction and adduction, and internal and external rotation. Occipital protuberance, ligamentum nuchae, and medial portion of … • Explain the force-couple that occurs to produce upward rotation of the scapula. In essence, this joint links the motion of the. An excellent example of this interaction is the, During normal shoulder abduction (or flexion), a natural 2 : 1 ratio or rhythm exists between the GH joint and the scapulo. The glenohumeral (GH) joint is created by the articulation of the humeral head with the glenoid fossa of the scapula (Figure 4-12). To illustrate this, first try to perform frontal plane abduction with your arm in full internal rotation (thumb pointing down), then in a neutral position (palm facing down), and finally in full external rotation (thumb pointing up). (From Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby, Figure 5-19, (From Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby, Figure 5-25. This means that for every 2 degrees of GH abduction, the scapula must simultaneously upwardly rotate roughly 1 degree. Because of the nature of this functional relationship among the shoulder muscles, paralysis, weakness, or tightness of any single muscle can disrupt the natural kinematic sequencing of the entire shoulder complex. The shoulder complex includes the movement of the scapula and clavicle to greater increase degrees of movement of the humerus. doi: 10.1097/BPO.0000000000001267. The larger, more rounded lateral projection of bone is the greater tubercle. Pectoralis major Teres major Movements of the Shoulder Complex Biomechanics of GH Stability • The normal shoulder constrains the humeral head to the center of the glenoid cavity throughout most of the arc of movement – Static restraints – Dynamic restraints Static restraints • Glenoid labrum and articular surfaces • Negative intra-articular pressure • Ligaments and capsule • Joint fluid adhesiveness … The clavicle rotates anteriorly, back to its rest position, as the shoulder is extended or adducted. 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. Physical therapy for these conditions usually involves regaining strength and range of motion and participating in a muscle stabilization program that fits the needs of the patient. These three segments are joined by three interdependent linkages: the sternoclavicular joint, the acromioclavicular (AC) joint, and the glenohumeral joint. Instead of your doctor simply saying that “the patient knee hurts”, he or she can say that “the patient’s knee hurts anterolaterally”. The articular structures of the shoulder complex, in particular the GH Joint, are designed primarily for mobility, allowing us to move and position the hand through a wide range of space, allowing the greatest range of motion of any joint in the body. Along with the acromion, the coracoacromial ligament completes the coracoacromial arch—a functional “roof” that protects the head of the humerus. Clinically, the inferior angle is important in helping track scapular motion. It must be understood, however, that movement of the entire shoulder is the result of movement in each of its four joints. Kinematics 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. 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. Doody SG, Freedman L, Waterland JC. Large forces that tax the biceps tendon can partially detach or tear the loosely attached superior labrum. It is one of four joints that comprise the shouldercomplex. This is a relatively common occurrence in throwing athletes such as baseball pitchers. Cite the normal ranges of motion for shoulder flexion and extension, abduction and adduction, and internal and external rotation. Osteology • Upward rotation of the scapula A, The rope indicates a muscular force that holds the glenoid fossa slightly upward. The shoulder joint is the main joint of the shoulder. In essence, dynamic stability exists when a moving segment or set of segments is limited very little by passive forces such as articular surface configuration, capsule, or ligaments and instead relies heavily on active forces or dynamic muscular control. Arthroscopic SLAP Repair. • 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. (From Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby, Figure 5-3.) The scapular plane is about 35 degrees anterior to the frontal plane (Figure 4-16, B). Much of the stability in the shoulder complex is … Acromioclavicular Joint • Cite the normal ranges of motion for shoulder flexion and extension, abduction and adduction, and internal and external rotation. In this episode of eOrthopodTV, orthopaedic surgeon Randale C. Sechrest, MD narrates an animated tutorial on the basic anatomy of the shoulder. Putting It All Together Recall that the head of the humerus is a large, rounded hemisphere, and that the glenoid fossa is relatively flat. Sternum The cords eventually branch into nerves that primarily innervate muscles of the upper extremity. The shoulder has several other important structures: The rotator cuff is a collection of muscles and tendons that surround the shoulder, giving it support and allowing a wide range of …   •   Accessibility. Supporting Structures of the Glenohumeral Joint, Numerous structural and functional reasons explain why the labrum is so often involved with shoulder pathology. Figure 4-7 The right sternoclavicular joint has been opened up to expose matching surfaces of the saddle joint. The following movements occur during a pulling motion, beginning at 90 degrees of shoulder flexion and moving to 10 degrees of extension. (From Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby, Figure 5-17.). During these actions, the humeral head spins on the glenoid fossa about a relatively fixed axis—an arthrokinematic roll and slide is not necessary. Because of the nature of this functional relationship among the shoulder muscles, paralysis. F. during open-chain abduction of the shoulder, the arthrokinematic roll and slide occur in the same direction. 7–1). This site uses cookies to provide, maintain and improve your experience. Dec 5, 2016 | Posted by admin in MANUAL THERAPIST | Comments Off on Structure and Function of the Shoulder Complex, Interaction Among the Joints of the Shoulder Complex. Figure 4-10 illustrates the supporting structures of the AC joint. Bankart lesions, on the other hand, involve tears to the anterior-inferior portion of the glenoid labrum. To fully understand how the shoulder functions as a whole, we must first examine the structure and kinematics of each individual joint. Rarely does a single muscle act in isolation at the shoulder complex. • Sternoclavicular Ligament: Contains anterior and posterior fibers that firmly join the clavicle to the manubrium “Put your shoulder to the wheel.” — Aesop (From Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby, Figure 5-5.) General Features The role of the scapula in athletic shoulder function. The limited range of motion experienced in a neutral or internally rotated position is caused by the greater tuberosity impinging against the acromion process. • Cite the proximal and distal attachments, actions, and innervation of the muscles of the shoulder complex. Upward rotation occurs as the glenoid fossa of the scapula rotates upwardly, as a natural component of raising the arm overhead (Figure 4-9, C). Scapular plane abduction is more natural than abduction in the pure frontal plane. • Describe the interaction between the internal and external rotators of the shoulder during a throwing motion. She reports feelings of tightness over the anterior chest region when she raises her right arm. The medial or sternal end of the clavicle articulates with the manubrium of the sternum, forming the sternoclavicular joint. … Structure and Function of the Shoulder Complex The SC joint allows motion in all three cardinal planes, and it is supported by a thick network of ligaments, an articular disc, and a joint capsule. The shoulder’s main motions are flexion, extension, abduction, adduction, internal rotation, and external rotation. The divisions then reorganize into lateral, medial, and posterior cords, named by their position relative to the axillary artery. The shoulder complex functions through the interactions of which four joints? 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. Figure 4-11 Osteokinematics of the right acromioclavicular joint. To reduce the disproportion in surfaces, the glenoid fossa is deepened by a fibrocart… List the three points of proximal attachment for the upper trapezius. • Rotator Cuff: A group of four muscles including the supraspinatus, infraspinatus, subscapularis, and teres minor. (From Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby, Figure 5-17.) The static locking mechanism helps provide stability to this loose-fitting joint. INTEGRATED FUNCTION OF THE SHOULDER COMPLEX. Y-T-W Drills. Discuss basic movement patterns of the shoulder complex … 2. Key Terms The shoulder is composed of three osseous joints and one articulation, with stability provided by muscles, ligaments, the glenoid labrum and joint capsule. Shoulder Flexion Nerves of the Shoulder. Along with the acromion, the coracoacromial ligament completes the coracoacromial arch—a functional “roof” that protects the head of the humerus. Box 4-1 summarizes the interactions among the joints during common shoulder motions. This bony conformation, in conjunction with the highly mobile scapula, allows for abundant motion in all three planes but does not promote a high degree of stability. The acromioclavicular (AC) joint is considered a gliding or plane joint, created by the articulation between the lateral aspect of the clavicle and the acromion process of the scapula (Figure 4-10). This freedom of movement makes the shoulder … Acromioclavicular and Sternoclavicular Joint Interaction Within the Scapulohumeral Rhythm 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. Internal and External Rotation This gives rise to the alternate name for the shoulder joint – the glenohumeral joint. Often seen with baseball and football players who are professional overhead athletes … Integrated Function of the Shoulder Complex … SHOULDER COMPLEX ANATOMY Osseous Elements The shoulder complex includes the articulations of the humerus, the clavicle, the scapula, and the posterior surface of the ribs. Study Questions • Describe the muscular interactions involved with active shoulder abduction. These muscles surround the humeral head and actively hold the humeral head against the glenoid fossa. The coracoid process is the site of attachment for several muscles and ligaments of the shoulder complex. With the shoulder in roughly 90 degrees of abduction, movement of the humerus toward the midline in the horizontal plane is considered horizontal adduction. (From Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby, Figure 5-13.) • Downward rotation and retraction of the scapula However, previous studies have failed to examine the sophisticated interrelationship between all muscles. The arthrokinematics of GH joint adduction is the same as that of shoulder abduction but in the reverse direction. Recent research findings are incorporated in this review of the functional anatomy of the shoulder complex. The osseous segments of the shoulder complex are the clavicle, scapula, and humerus (Fig. The cooperative nature of the shoulder musculature increases the versatility, control, and range of active movements available to the upper extremity. The larger, more rounded lateral projection of bone is the greater tubercle. In essence, all movements of the shoulder girdle (i.e., the scapula and clavicle) originate at the SC joint. Chapter 4 • Glenoid Labrum: A fibrocartilaginous ring that encircles the rim of the glenoid fossa. 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. 120 degrees of glenohumeral joint abduction • Cite the normal ranges of motion for shoulder flexion and extension, abduction and adduction, and internal and external rotation. 30 degrees of sternoclavicular joint elevation, + 30 degrees of acromioclavicular joint upward rotation, = 60 degrees of scapulothoracic joint upward rotation. The superior and inferior glenoid tubercles border the superior and inferior aspects of the glenoid fossa and serve as proximal attachments for the long head of the biceps and the long head of the triceps, respectively. The proximal humerus (Figure 4-5) is the point of attachment for a multitude of ligaments and muscles. Her history also includes a right acromioclavicular joint separation many years ago, for which she was immobilized in a sling for several weeks with no further treatment. The glenohumeral (GH) joint is created by the articulation of the humeral head with the glenoid fossa of the scapula (Figure 4-12). You may also needStructure and Function of the Elbow and Forearm ComplexStructure and Function of the HandStructure and Function of the Ankle and FootStructure and Function of the HipStructure and Function of the KneeStructure and Function of the WristStructure and Function of JointsStructure and Function of the Vertebral Column The SC joint structure is a saddle joint with concave and convex surfaces on each of the joint’s articular surfaces (Figure 4-7). ), (From Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby, Figure 5-3. Horizontal abduction and horizontal adduction are commonly used terms to describe special motions of the shoulder and are described in the following section.

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