It has been proposed by Hodgson, in order to place a ligature around the axillary artery in the first stage, to cut between the pectoral and deltoid muscles, and then to separate the clavicular attachment of the great pectoral to an extent sufficient for insulating and tying the artery.
As in other radiated muscles, the tendinous structure of the deltoid is chiefly placed in its interior ; as many as three or four laminx attached to the bone above, penetrate into the substance of the muscle, and multiply the points of origin of its fleshy fibres. The fasciculi, of vvhich the deltoid muscle is com posed, like those of the glutmus maximus, which is its analogue in the lower extremity, are remarkably coarse and large.
When the deltoid is cut across and reflected, the following parts are found in relation with its deep surface ; anteriorly is seen the cora coid process and the insertions of the pectora lis minor, of the coraco-brachialis, and of the short head of the biceps into its inner edge, and of the ligamentum bicorne (coraco-clavi cular ligament) into its summit ; external to the coracoid process is a triangular space, the sides constituted by the opposed edges of the coracoid and acromion processes, the apex placed superiorly at the clavicle, the base inferiorly formed by the convex promi nence of the head of the humerus ; this space, filled by the coraco-acromial or triangular ligament, should be familiar to the surgeon, as the point of the knife tnust be here introduced when disarticulation at the shoulder-joint is being performed after the method of MM.
Champesme and Lisfranc. Immediately be neath the coraco-acrornial triangle the capsular ligament is situated, and a large bursa (sub deltoid) which intervenes between it and the deep surface of the deltoid muscle ; still lower down, the insertions of the capsular muscles into the tuberosities of the humerus, also the neck of the humerus, and the bicipital groove, present themselves. The bicipital groove looks directly forwards and lodges the long tendon of the biceps ; into its anterior-edge the tendon of the pectoralis major is inserted, whilst those of the latissimus dorsi and teres major take attachment to the very bottom of the groove, passing a little below the level of the former. The anastomosis of the circum flex arteries, and the circumflex nerve in a great part of its course, constitute also re markable relations to the deltoid, separating it from the neck of the humerus ; and under the posterior division of the nmscle are placed the infra-spinatus, teretes and latissimus dorsi muscles, with the triangular and quadrilateral spaces which they circumscribe. (Vide SCA