Anatomy Study Materials

1. ANATOMY The anatomy of the shoulder girdle includes seven bones (shoulder blades, clavicles, sternum and upper ends of the humerus), six joints and their corresponding muscles. 1 Translated from French to English - www.onlinedoctranslator.com 1.1 OSTEOLOGY ➢ Shoulder blade The scapula has two sides, an articular cavity and two processes, the acromion and the coracoid. . ● The anterior surface is excavated, it gives insertion almost entirely to the muscle subscapularis. On its internal edge from top to bottom is inserted the large serrated edge. The long portion of the triceps originates on its outer edge, under the glenoid cavity, while the long biceps inserts above this cavity. . ● The posterior surface is divided into two fossae by the spine of the scapula. These two fossae give rise to the supraspinatus and infraspinatus. On the outer edge are inserted from top to bottom the long portion of the triceps, the teres minor, the teres major and the latissimus dorsi. On its internal edge it gives insertion to the angular and the rhomboids. On the spine of the scapula the trapezius muscle is inserted at the top and the deltoid at the bottom. . ● The acromion extends the spine of the scapula. It presents on its antero-internal face an articular facet intended for the clavicle. The only muscle inserting in this process is the deltoid. . ● The coracoid process is made up of two parts, a vertical branch and a horizontal branch oriented from back to front from the inside to the outside. At the end of this process the biceps brevis and the coraco-brachialis are inserted by a common tendon. On the internal face of this branch is inserted the small pectoral. . ● The glenoid labrum is made up of a fibro-cartilaginous ring placed on the around the glenoid cavity of the scapula. It is a triangular cartilage with three faces (peripheral, articular and bony). In its upper part the rim is only joined to the edge of the glenoid cavity, its internal, free face is only applied to the glenoid cartilage, and therefore has the characteristics of a meniscus. The function of the glenoid labrum is to increase the depth of the cavity. It is a stabilizer of the glenohumeral joint. ➢ Clavicle The clavicle extends from the acromion to the sternum. Its stability is ensured by the acromioclavicular and sternoclavicular joints, but also by the trapezoid, conoid and coracoclavicular ligaments. The clavicle serves as a fulcrum for many muscles; to the trapezius, deltoid, pectoralis major and sternocleidomastoid on its upper surface, to the subclavius and sternocleidomastoid on its lower surface. ➢ Sternum The sternum is made up of three odd and symmetrical pieces of bone which only participate in the shoulder girdle at the level of the sternoclavicular joint. The sternum as we know it today is the result of the fusion of independent bony parts, the sternebrae. The manubrium articulates with the first rib and the clavicle superiorly, the second rib at its junction with the sternal body. The body, flat and elongated, has sixternal notches on each side. The joint of the manubrium and the body form a dihedral angle projecting anteriorly. The xiphoid joint is often cartilaginous. On its anterior surface the manubrium and the body give insertion to the sternocleidomastoid muscles and the pectoralis major. ➢ Humeral head The upper end of the humerus presents, in addition to the head of the humerus (joint area), two tuberosities separated by the anatomical neck. The greater tuberosity is located outside the head on the 2 extension of the outer edge of the bone, while the trochin is positioned on the anterior surface of the humerus. These two tuberosities are separated by an osteo-fibrous groove in which the tendon of the long biceps slides. The greater tuberosity presents on its upper and posterior surface three facets which give respectively insertion to the supraspinatus, infraspinatus and teres minor muscles. The subscapularis muscle is inserted on the trochin. The banks of the bicipital groove provide insertion on the external side to the pectoralis major and on the internal side to the teres major and latissimus dorsi.