University:
Stanford University
Course:
MED 101 | Human Anatomy
Academic year:

2023
Views:

184

Pages:

2
Author:

larbi43100

PHYSIOLOGY JOINT PHYSIOLOGY ➢ Scapulohumeral joint This joint can achieve: ❉ Movements following a transverse axis passing through the center of the humeral head and parallel to the plane of the scapula: . ● The flexion movement (antepulsion) is carried out by the coraco-brachialis, the fasciculus anterior of the deltoid, the short portion of the biceps, the superior bundle of the pectoralis major. It is stopped by tension of the coracohumeral ligament. Its maximum amplitude is °, the scapulo-humeral is sufficient for its realization, beyond this angle there is an internal rotation of the scapula. . ● The extension movement (retropulsion) is caused by the contraction of the large teres, teres minor and posterior fascicles of the deltoid. If the retropulsion is prolonged the rhomboids, the latissimus dorsi and the trapezius participate in the movement. Extension is stopped by tension of the coracohumeral ligament. Its maximum amplitude is ° .Movements carried out around an antero-posterior axis passing through the center of the humeral head and perpendicular to the plane of the scapula. . ● The abduction movement is caused by the simultaneous contraction of the deltoid which is the only active abductor and the supraspinatus whose role is to press the humeral head against the glenoid cavity and thus prevent its elevation. This latter mechanism is reinforced by the capsuloligamentous vault. The movement is limited by the contact of the greater tuberosity against the glenoid cavity (0°), then by the mobility of the scapula. Its maximum amplitude is °. Up to 0° only the glenohumeral joint participates in the movement. Beyond this value, rotation of the scapula is essential. . ● The adduction movement is caused by the contraction of the pectoralis major, latissimus dorsi and subscapularis. This is a movement most often performed during pull-ups, that is to say when the arm is already in abduction. Its maximum amplitude is a few degrees. Adduction is limited by the meeting of the arm with the trunk. ❉ Movements made around an axis passing through the center of the humeral head and parallel to that of the body. . External rotation is caused by the infraspinatus and teres minor. Its amplitude maximum is °. External rotation is limited by the tension of the joint capsule and the internal rotator muscles. . Internal rotation is caused by contraction of the subscapularis, major pectoral, teres major and latissimus dorsi. Its maximum amplitude is 0°. It is limited by the tension of the capsule and the external rotators. ❉ Complex movements integrating abduction/adduction and flexion/extension This type of movement, called circumduction, requires the participation of all the joints of the shoulder girdle. ➢ Acromioclavicular joint This joint has the particularity of being able to perform sliding movements of very low amplitude, but in all planes of space. These movements allow the scapula to rotate and rock around this point. The opening movement of the scapula relative to the clavicle is limited by the conoid ligament, closing by the trapezoid ligament.