Rhomboids Study Resources

Rhomboids The small and large rhomboids insert on the spinous processes and the ligament interosseous corresponding to the seventh cervical and the first four dorsal vertebrae. Its fibers orient downwards and outwards to end on the spinal border of the scapula, from the spine to the inferior angle. The rhomboids are an elevator of the scapula and depressors of the shoulder stump. ❉ Angular of the scapula The angular scapula is an elongated muscle that extends from the superomedial angle of the scapula to the first five cervical vertebrae. When the fixed point is the angle of the scapula, this muscle tilts the cervical spine. Conversely, when the fixed point is cervical, the angular tilts the scapula downward and outward by lowering the shoulder stump. ❉ Large serrated The muscular body of the serratus major and its insertions are practically never injured during physical exercise. The only pathology frequently encountered concerns its nerve, also called Charles-Bell nerve. The serratus major is a broad, flattened, thin muscle that is applied to the lateral wall of the thorax. It wraps around the thorax, from the spinal edge of the scapula to the first ten ribs. This muscle is separated from the chest wall by a cellular space which has the function of facilitating the sliding movements of the scapula on the thorax. The function of this muscle is twofold: . When it contracts by resting on the ribs, it attracts the scapula in forward and out, giving it a rotational movement which elevates the external angle of the scapula and the stump of the shoulder. . Conversely, when the fixed point is constituted by the scapula, it elevates the ribs and in this case plays an inspiring role. Upper muscles ❉ Trapezoid The trapezius is a flat, triangular muscle that connects the cervico-dorsal spine to the shoulder. It arises from the posterior cervical ligament, from the spinous processes of the seventh cervical to the tenth dorsal. All of the muscle fibers are carried outwards to end on the clavicle, the acromion and the spine of the scapula. The action of this muscle is complex because it depends on the muscle bundles involved. The upper fibers carry the shoulder upward and medially, the middle fibers carry the scapula medially and raise the shoulder stump, the lower fibers lower the spinal edge of the scapula while elevating the stump of the shoulder. ❉ Deltoid The deltoid muscle covers the shoulder stump. It connects the shoulder girdle to the external surface of the humerus. It originates from fibers originating on the anterior edge of the clavicle, the top of the acromion and the spine of the scapula. These fibers form a thick fusiform mass which covers the scapulohumeral joint. It ends on the external surface of the humerus. The deltoid is the most powerful abductor of the arm. ❉ Subscapularis This muscle, located on the anterior surface of the scapula, extends from the subscapular fossa to the upper end of the humerus. It ends in a tendon and tendon fibers on the part superior to the subtrochanteric ridge. It is separated from the coracoid process by a serous bursa called "subcoracoid", and from the joint capsule by a second bursa called subscapularis. The subscapularis is an internal rotator of the arm. ❉ Pectoral major The pectoralis major extends from the anterior edge of the clavicle, half of the sternum, the first six costal cartilages and the rectus abdominis sheath to the anterior lip of the bicipital slide. The pectoralis major is the adductor and internal rotator of the arm. ❉ Small pectoral The pectoralis minor extends from the third, fourth, and fifth ribs of the coracoid process. When it takes its fixed point on the ribs, the small pectoral lowers the shoulder stump. Conversely, it becomes inspirational when the fulcrum is coracoid. ❉ Coracobrachial The coracobrachialis is a fusiform muscle that inserts on the coracoid process medial to the insertion of the short portion of the biceps. It runs along the latter until its insertion on the internal face of the humerus. The coracobrachialis carries the arm forward and inward. This muscle is only exceptionally injured during sports practice. Only high insertion tendonitis can sometimes be highlighted.