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Anatomy, Shoulder and Upper Limb, Scapulohumeral Muscle
Jonathan G. Wu; Bruno Bordoni.Author Information
The scapulohumeral muscles are muscles that connect the scapula come the humerus.<1> The articulation in between the glenoid area the the scapula and also the head that the humerus is in between the joints v greater ability to perform active and passive movements. Its capacity to relocate makes this coupling very facility from the biomechanical suggest of view; the muscles that influence its activities must be in perfect neuromotor, metabolic, and structural synergy. Every single movement performed wake up in the three-dimensional space and each muscle, depending on the activity performed, plays different roles. The shoulder musculature no only have actually the task of relocating the joint, yet it also has the obligation of maintaining it healthy due to the fact that the exactly muscular intervention stays clear of instability and also conflicts of joint articulation.
Structure and also Function
The scapulohumeral muscle dynamically position the glenoid effectively in the glenohumeral socket and are vital because that the function of the glenohumeral joint. They coordinate the movement of the scapula and humerus to allow efficient motion to take place. The movement of these two joints is quantifiable v scapulohumeral rate (SHR).<2>
The supraspinatus originates indigenous the supraspinous fossa.<3> the inserts at the exceptional facet the the better tuberosity the the humerus. Its role is the abbot of the humerus and lateral rotation that the humerus.<3>
Infraspinatus originates indigenous the infraspinous fossa of the scapula, situated on the dorsal element of the scapula listed below the scapular spine.<4> it inserts on the center facet the the greater tuberosity. Its primary function is the exterior rotation the the shoulder joint and also the abbot of the scapula.<4>
Teres young originates native the posterior part of the scapular, alongside the lateral border.<5> it inserts at the better tubercle of the humerus. The teres minor’s function is come externally revolve the upper arm in ~ the shoulder joint. The is one antagonist to inner rotation.<5>
Subscapularis originates at the medial and also lower two-thirds of the lateral border that the subscapular fossa. That inserts ~ above the lesser tubercle that the humerus. The subscapularis inside rotates the humerus. In specific positions, the subscapularis gives adduction and extension.<6>
Deltoid originates from the spine of the scapula and lateral 3rd of the clavicle. That inserts in ~ the lateral humerus at the deltoid tuberosity. It has three parts, an anterior, lateral, and posterior. Together, the deltoid abducts the arm previous fifteen degrees. The anterior and also posterior portions stabilize the arm. The lateral component raises the arm from 15 come 100 degrees.<7>
Teres significant originates native a lower one-third that the lateral scapula. The inserts medially come the intertubercular groove. Its role is to carry out shoulder extension, adduction, and also internal rotation.<8>
Coracobrachialis originates native the coracoid process and inserts in ~ the medial element of the middle of the humerus.<1> Its duty is flexion and adduction that the arm.
The biceps brachialis muscle originates v its lengthy head from the supraglenoid tubercle that the scapula and with its brief head from the coracoid process of the scapula. Its activity at shoulder level is come flex and also facilitate adduction on a horizontal plane. Both top of which that is composed sign up with at the level of the deltoid tuberosity that the humerus and, many thanks to a usual tendon, castle are placed at the level that the radial tuberosity and also on the fascia that the forearm indigenous the ulnar side.
The brachial triceps creates from three parts, namely lengthy head, lateral head, and medial head. The lengthy head occurs from the subglenoid tuberosity that the scapula and the glenoid labrum. The lateral head is born native the posterior element of the humerus, above and laterally to the groove of the radial nerve. The medial head originates from the posterior element of the humerus, worse to the groove the the radial nerve. The 3 muscular heads are lugged downwards converging top top a solid tendon that goes to insert itself to the superior and posterior faces and also the margins of the olecranon. The lengthy head that the brachial triceps intervenes in the extension of the arm and also the posterior adduction.
The latissimus dorsi muscle creates the posterior pillar and the posterior wall surface of the axillary cavity. The covers the lower and lateral political parties of the ago (lumbar region) and also the lateral component of the chest. That originates, with the posterior leaflet the the lumbodorsal fascia, native the spinous procedures of the last six thoracic vertebrae and also the lumbar vertebrae, from the supraspinous ligament, the medial sacral crest, and also the posterior 3rd of the outside lip of the iliac crest. Several of its fibers also originate indigenous the outer confront of the last 3 or 4 ribs. The muscular majority are carried up and also out towards the axillary region reaching the insertion line on the medial lip of the bicipital groove the the humerus (crest that the tiny tuberosity). In ~ the level of the shoulder, that is the most vital internal rotator, together it is the most crucial for the adduction and flexion that the shoulder.
The pectoralis significant muscle is situated anteriorly in the thorax and also forms much of the anterior wall of the axillary cavity. Over there is a clavicular head, a sternum-costal head, and also an abdominal muscle head. The majority of the three components converge outwards and insert with a flattened tendon in ~ the lateral lip the the bicipital groove the the humerus (crest the the great tuberosity). Its convulsion at shoulder level helps flexion, inner rotation, and also adduction on a horizontal plane.
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The trapezius muscle is located in the nuchal an ar and the dorsal part of the thorax. That originates native the medial 3rd of the superior nuchal line, indigenous the external occipital protuberance, the nuchal ligament, and the spinous processes of the saturday cervical vertebra and also of all the thoracic vertebrae, and from the supraspinous ligament. Its bundles converge in the direction of the shoulder and are put at the lateral 3rd of the posterior margin that the clavicle, at the medial margin of the acromion, at the upper lip the the posterior margin that the spine of the scapula and also at the medial finish of the spine itself. Its activity influences the activities of the scapula and indirectly help the shoulder in adduction and flexion in the very first degrees.