THE MEDIASTINUM. 187 



those along the subclavian vessels may be enlarged and may be felt above the clavicle 

 and farther inward behind the sternomastoid muscle low down. 



In rare instances the disease may be carried superficially to the subclavian nodes 

 in the infraclavicular triangle between the deltoid and pectoralis major muscles. 

 Should the disease spread, it may be carried by the lymphatics to the opposite breast 

 directly across the median line. If it involves the lymphatics of the chest-wall gen- 

 erally there is produced the brawny condition of the skin called cancer ' ' en cuirasse ' ' 

 of Velpeau already alluded to. A cancerous nodule beyond the edge of the pectoralis 

 major muscle is not necessarily an enlarged node, but may be due to the involvement 

 of one of the cusps of the gland, which sometimes extend even into the axilla. 



Removal of the Cancerous Breast. The origin of cancer is now believed 

 to be local and not general and the more complete its removal the greater is the 

 likelihood of cure. Therefore every effort is made to excise every possible infected 

 tissue. This has led to the performance of very extensive operations. 



The incision is made so large as to include nearly or quite all of the skin 

 covering the glandular tissue; this is because of the intimate connection of the 

 two, as already pointed out. It is carried out to the arm; this is to facilitate 

 clearing out the axilla and all its contents. The incision is kept close to the skin; 

 this is to avoid any glandular structure which may possibly be beneath. The 

 pectoral fascia covering the pectoral muscle is always removed. 



Often both the pectoralis major and minor muscles are removed. In excising 

 them the slight interspace between the clavicular and sternal fibres of the pectoralis 

 major muscle is entered and the muscle detached from the anterior extremities 

 of the ribs and sternum. In so doing the anterior intercostal arteries, particularly 

 those of the second, third, and fourth spaces, are liable to bleed freely. As the 

 pectoralis major is detached and turned outward, the acromial thoracic artery is 

 seen at the inner edge of the pectoralis minor muscle with its pectoral branch 

 running down the surface of the chest. This may be ligated, the finger slipped 

 beneath the pectoralis minor, and this muscle cut loose from the coracoid process 

 above and the third, fourth, and fifth ribs below. At this stage some operators 

 clear the subclavian and axillary vessels of all loose tissues and lymph-nodes. 



The vessels are followed out on the arm. When the insertion of the pecto- 

 ralis major is reached it is detached and the whole mass turned outward and pared 

 loose along the anterior edge of the scapula. Thus it is removed in one piece. 

 The part of the chest-wall which has been cleared off embraces from the middle 

 or edge of the sternum to the anterior edge of the scapula and from near the 

 lower edge of the chest below to the clavicle above. The vessels have been 

 cleared off from the insertion of the axillary folds on the arm to underneath the 

 clavicle. Many operators make an additional incision above the clavicle and clear 

 out the supraclavicular fossa even if no enlarged glands can there be detected. 

 Sometimes the long thoracic artery and thoracicalis longus (long external thoracic) 

 nerve may be wounded, but they need not be. 



Two nerves will be seen crossing the axilla from the chest to the arm. They 

 are the lateral branches of the second and third intercostal nerves. The second is 

 called the intercostobrachialis (humeral) nerve. If they can conveniently be spared 

 it is to be done, otherwise they are divided. In clearing the axillary vessels, small 

 veins and even arteries may be divided close to the main trunks. These may 

 be expected to bleed freely but are usually readily secured. Care should be taken 

 not to wound unnecessarily the subscapular artery and particularly the vein as they 

 wind around the anterior edge of the scapula 2 to 3 cm. below its neck. Some operators 

 prefer to detach the breast from without in instead of from within out as described. 



THE MEDIASTINUM. 



The mediastinum is the middle space of the chest between the spine behind, the 

 sternum in front, and the pleurae to each side. It is subdivided into a superior 

 mediastinum, which is the part above Ludwig's angle, between the first piece of the ' 

 sternum in front and the vertebrae from the first thoracic to the upper portion of the 

 fifth behind. The part below is divided into the anterior mediastinum, the middle 

 mediastinum, and \.\\e posterior mediastinum. 



