18 



DISSECTION OF THE UPPER LIMB. 



inside. 



Lymphatic 

 glands 

 of the 

 axilla 



and vessels 

 them 18 



On the inner boundary, at the upper part, are a few small 

 branches of the superior thoracic artery, which ramify on the 

 serratus muscle ; but these are commonly so unimportant, that 

 this part of the axillary space may be considered free from vessels 

 with respect to any surgical operation. Eunning down the outer 

 surface of the serratus magnus towards the back of the axilla is 

 the nerve to that muscle (long or posterior thoracic) ; and coming 

 through the inner wall of the space, under cover of the pectoral 

 muscles, are the lateral cutaneous nerves of the thorax, the 

 highest of which is directed across the axilla to the arm, and 

 receives the name intercosto-humeral ( 7 ). 



The lymphatic glands of the axilla are arranged in three sets : 

 one is placed along the inner side of the great blood-vessels ; 

 another occupies the hinder part of the space, lying near the sub- 

 scapular vessels ; and the third accompanies the long thoracic 

 artery, beneath the margin of the pectoralis major. Commonly 

 there are in all ten or twelve ; but in number and size they vary 

 much. Small twigs from the branches of the axillary vessels are 

 furnished to them. 



The glands by the side of the blood-vessels receive the lymphatics 

 of the arm ; those along the hinder boundary are joined by the 



FIG. 5. THE CLAVICLE, SHOWING THE UPPER AND A PART 

 OP THE ANTERIOR SURFACE. 



Pectoralis 

 major ; 



origins ; 



insertion 



relations. 



lymphatics of the side of the chest and of the back, and those 

 beneath the pectoral muscle by the lymphatics of the front of the 

 chest, and from the outer part of the mamma. The efferent 

 vessels unite to form a trunk, which opens into the lymphatic duct 

 of the neck of the same side ; or some may enter separately the 

 subclavian vein. 



The PECTORALIS MAJOR (A) is triangular in shape, with the base 

 at the sternum, and the apex at the arm. It arises from the inner 

 half of the front of the clavicle (fig. 5), from the anterior surface of 

 the sternum and the cartilages of the upper six ribs, and below 

 from the aponeurosis of the external oblique muscle of the abdomen. 

 From this wide origin the fibres take different directions those 

 from the clavicle being inclined obliquely downwards, while the 

 lower ones ascend behind the upper portion of the muscle ; and all 

 end in a tendon, which is inserted (fig. 17, p. 44) into the pectoral 

 ridge on the outer side of the bicipital groove of the humerus, along 

 which a thin prolongation is sent upwards to the head of the bone. 



This muscle bounds the axilla in front, and its lower border 



