INTERNA L MAMMAR Y 



517 



then between the pleura and the vena cava superior; and lastl}', between the pleura 

 and the pericardium to the diaphragm, where it anastomoses with the other dia- 

 phragmatic arteries. It gives brandies both to the pleura and i)ericardium. 



(2) The mediastinal or thymic branches come off irregularly from the internal 

 mannnary. They arc of small size, and supply the connective tissue, fat, and 

 lym})hatics in the superior and anterior mediastina and the rt^-mains of the thymus 

 gland. 



(3) The pericardiac branches are distriV)uted to the anterior surface of the 

 pericardium. 



(4) The sternal branches enter the nutrient foramina in the sternum, and also 

 supply the triangularis sterni. 



Fig. 344. — Scheme of the Kioht Interxal Mammary Artery. (Walshani. 



Common carotid artery 



PHRENIC ySR VE 



Subclavian artery 

 Subc/ariaH rein, cut 



A nterior intercostal brancli 



Anterior intercostal branch 



Mnscnlo-phrenic artery 



Deep circumflex iiiae artery 



Internal jugular vein 

 Siihrlavian vein, cut 

 Scalenus anticus muscle 



Triangularis sterni muscle 



Perforating branch 



Superior epigastric artery 



Deep epigastric artery 



(5) The anterior intercostal arteries (fig. 344) — two in each of the live or 

 six ui)per intercostal s}nices — run outwards from the internal mammary artery, 

 along the lower border of the ril) ahovc and the up])cr l)order of the rib below, and 

 anastomose with the corresponding uj)))er and lower liranches of the aortic intcr- 

 costals. Each pair of branches sometimes arises by a common trunk from the in- 

 ternal mammary, which in this case soon divides into an upper and a lower branch, 

 as above described. They lie at first between the internal intercostal muscles and 

 the pleura; afterwards between the external and internal intercostal muscles. They 

 supply the contiguous muscles, the ]-)ector:ilis major, and the ribs. 



(6) The perforating or anterior perforating branches — five or six in number, 

 one corresponding to each of the five or six upper spaces — come off from the front 



