300 AXILLARY ARTERY. 



The Anterior intercostals supply the intercostal muscles of the front of 

 the chest, and inosculate with the aortic intercostal arteries. Each of the 

 first three anterior intercostals gives off a large branch to the mammary 

 gland, which anastomoses freely with the thoracic branches of the axillary 

 artery ; the corresponding branches from the remaining intercostals supply 

 the integument and pectoralis major muscle. There are usually two an- 

 terior intercostal arteries in each space. 



The Comes nervi phrenici is a long and slender branch which accom- 

 panies the phrenic nerve. 



The mediastinal and pericardiac branches are small vessels distributed 

 to the anterior mediastinum, the thymus gland, and pericardium. 



The Musculo-phrenic artery winds along the attachment of the diaphragm 

 to the ribs, supplying that muscle, and sending branches to the inferior 

 intercostal spaces. " The mammary arteries," says Dr. Harrison, " are 

 remarkable for the number of their inosculations, ,and for the distant parts 

 of the arterial system which they serve to connect. They anastomose with 

 each other, and their inosculations, with the thoracic aorta, encircle the 

 thorax. On the parietes of this cavity their branches connect the axillary 

 and subclavian arteries ; on the diaphragm they form a link in the chain 

 of inosculations between the subclavian artery and abdominal aorta, and 

 in the parietes of the abdomen they form an anastomosis most remarkable 

 for the distance between those vessels which it serves to connect ; namely, 

 the arteries of the superior and inferior extremities." 



Varieties of the subclavian Arteries. Varieties in these arteries are rare ; 

 that which most frequently occurs is the origin of the right subclavian, 

 from the left extremity of the arch of the aorta, below the left subclavian 

 artery. The vessel, in this case, curves behind the CESOphagus and right 

 carotid artery, and sometimes between the esophagus and trachea, to the 

 upper border of the first rib on the right side of the chest, w r here it assumes 

 its ordinary course. In a case* of subclavian aneurism on the right side, 

 above the clavicle, which happened during the summer of 1839, Mr. Lis- 

 ton proceeded to perform the operation of tying the carotid and subclavian 

 arteries at their point of division from the innominata. Upon reaching 

 the spot w r here the bifurcation should have existed, he found that there 

 was no subclavian artery. With the admirable self-possession which dis- 

 tinguishes this eminent surgeon in all cases of emergency, he continued 

 his dissection more deeply, towards the vertebral column, and succeeded 

 in securing the artery. It was ascertained after death, that the arteria 

 innominata was extremely short, and that the subclavian was given off 

 within the chest from the posterior aspect of its trunk, and pursued a deep 

 course to the upper margin of the first rib. In a preparation which was 

 shown to me in Heidelberg some years since by Professor Tiedemann, 

 the right subclavian artery arose from the thoracic aorta, as low down as 

 the fourth dorsal vertebra, and ascended from that point to the border of 

 the first rib. Varieties in the branches of the subclavian are not unfre- 

 quenc ; the most interesting is the origin of the left vertebral from the arch 

 of the aorta, of which I possess several preparations. 



AXILLARY ARTERY. 



The axillary artery forms a gentle curve through the middle of the 



This case is recorded in the Lancet, vol. i. 1839-40, pp. 37 and 419. 



