This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
A modification of Larrey's procedure, attributed to Spence by the British and to S. Fleury by the French, consists in commencing the incision just outside of the coracoid process in the interval between it and the acromion process. This modification is probably the best form of procedure for this locality and is the one which will be discussed here. It will be noticed, however, that it practically changes the operation of Larrey from one with anteroposterior flaps to one with a single external flap, as in the method of Dupuytren. (Fig. 263).
The incision begins just below the coraco-acromial ligament and lies deep in the hollow formed by the anterior concave surface of the outer third of the clavicle. It divides the fibres of the deltoid muscle longitudinally a short distance from its anterior edge. It will be recalled that the deltoid muscle covers the coracoid process and extends just to its inner side to be attached to the outer third of the lower surface of the clavicle. Between it and the adjoining edge of the pectoralis major muscle runs the cephalic vein. This passes downward and outward along the inner edge of the deltoid until it reaches the outer edge of the biceps muscle alongside of which it passes down to the elbow. This vein will be cut as the inner branch of the incision is made. The bicipital groove, when the palm of the hand faces forward, lies almost directly below the coraco-acromial ligament. While the incision is being made the arm is kept rotated slightly outward.
As the knife descends it runs along the inner side of the bicipital groove and divides the tendon of the pectoralis major muscle. As soon as this tendon is cut the incision is inclined laterally. The incision having been carried down to the bone, except on the inside of the arm, the deltoid flap is raised upward and backward. It carries with it the circumflex nerve and posterior circumflex artery.
The disarticulation of the bone is apt to be bungled unless one knows the construction of the parts. It is to be borne in mind that the capsular ligament is to be divided together with the tendons of the muscles inserted into the tuberosities. The capsule does not pass across the anatomical neck to be inserted into the tuberosities beyond, and the mistake is often made of cutting on the anatomical neck and therefore frequently the capsule still remains attached to the proximal side. The cut may be commenced posteriorly and should be made on the head of the bone just above the anatomical neck. The arm is to be adducted and rotated inward and the muscles inserting into the greater tuberosity cut in their order, first the teres minor, then the infraspinatus and supraspinatus with the joint capsule beneath them. Then comes the long head of the biceps, and the arm now being rotated outward, the tendon of the subscapularis is divided. In cutting the muscles and capsule across the top of the joint, the arm is to be kept close to the side of the body so as to tilt the upper portion of the capsule out beyond the acromion process.
The head of the bone can now be drawn out sufficiently to allow the knife to be introduced behind it to divide the inferior portion of the capsule. This should be detached close to the bone so as to avoid wounding the axillary artery and especially the posterior circumflex artery and the circumflex nerve, which wind around the surgical neck immediately below and are to be pushed out of the way.
The division is completed by cutting the remaining muscles passing from the trunk to the shaft of the bone. On the inner side may be an uncut portion of the pectoralis major, the coracobrachialis, and short head of the biceps; below is the long head of the triceps and on the outer side are the teres major and latissimus dorsi.
On examining the face of the stump, posteriorly is seen the bulk of the deltoid muscle with the triceps below, and then the latissimus dorsi and teres major tendons lying next to the artery. Anteriorly is the cut edge of the deltoid and pectoralis major with the coracobrachialis and short head of the biceps lying next to the artery.
To the outer side of the artery lie the median and musculocutaneous nerves. To the inner side are the ulnar and lesser internal cutaneous nerves (cutaneus brachii media/is) and the axillary vein. Posteriorly are the musculospiral and axillary
(circumflex) nerves. Sometimes the median nerve lies in front instead of to the outer side. The axillary artery is divided below the origin of the anterior and posterior circumflex arteries. The bleeding in the first cut will be from the cephalic vein (which runs between the pectoralis major and deltoid), muscular branches of the posterior and anterior circumflex, a small ascending branch of the anterior circumflex which runs in the bicipital groove, and the humeral branch of the acromial thoracic which accompanies the cephalic vein.
A glaring and common mistake in the performance of shoulder amputations is the making of the flaps entirely too short, especially when a Larrey operation is attempted.
The avoidance of serious hemorrhage is usually accomplished by clamping the small vessels as the operation proceeds, and before the final division of the axillary vessels slipping the fingers behind the bone and compressing them.
Esmarch's tube has been used by encircling the shoulder as close to the trunk as possible, the tube being kept from slipping by a bandage passed beneath it and fastened to the opposite side. Wyeth's pins have been used for the same purpose. One is inserted through the lower edge of the anterior axillary fold a little internal to its middle and brought out above in front of the acromion process, the other is entered at a corresponding point of the posterior fold and brought out above just behind the angle of the spine of the scapula or acromion process.