BRANCHES OF THE SUBCLAVIAN ARTERY. 781 
(c) Pericardial.—These are several small branches which ramify on the anterior aspect 
of the pericardium. 
(dq) The anterior intercostal (rami intercostales), are two in number in each of the 
upper six intercostal spaces. They pass outwards for a short distance either between the 
pleura or the triangularis sterni and the internal intercostal muscles; they then pierce 
the internal intercostal muscles, and ramify between them and the external intercostal 
muscles, anastomosing with the aortic and superior intercostal arteries and their collateral 
branches. 
(ec) The anterior perforating branches (rami perforantes), one in each of the upper six 
intercostal spaces, are small vessels which pass forwards with the intercostal nerves, 
piercing the internal intercostal muscle, the anterior intercostal membrane, and the 
pectoralis major, to terminate in the skin and subcutaneous tissue. They supply twigs 
to the sternum, and those in the third and fourth spaces, usually the largest of the series, 
give off branches to the mammary gland. 
(7) The musculo-phrenic (a. musculo-phrenica), or external terminal branch of the 
internal mammary artery, runs downwards and outwards from the sixth intercostal space 
to the tenth costal cartilage. In the upper part of its course it les upon the thoracic 
surface of the diaphragm, but it pierces the muscle about the level of the eighth costal 
cartilage, and terminates on its abdominal surface. Its branches are :—- 
(i) Muscular, which supply the diaphragm and anastomose with the superior and inferior 
phrenic arteries. 
(ii.) Anterior intercostal branches, two in each of the seventh, eighth, and ninth intercostal 
spaces; they are distributed in the same manner as the corresponding branches of the internal 
ay artery, and terminate by anastomosing with the aortic intercostals and their collateral 
pranches, 
(7) The superior epigastric (a. epigastrica superior), or internal terminal branch of the 
internal mammary artery, descends into the anterior wall of the abdomen. It leaves the 
thorax, between the sternal and costal origins of the diaphragm, and enters the sheath of 
the rectus, lying first behind, and then in the substance of the rectus muscle. It termi- 
nates by anastomosing with branches of the deep epigastric artery. Its branches are : 
(i.) Muscular, to the rectus, to the flat muscles of the abdominal wall, and to the diaphragm. 
(ii.) Anterior Cutaneous.—These branches pierce the rectus and the anterior portion of its 
sheath. They accompany the anterior terminal branches of the lower six intercostal nerves, and 
terminate in the subcutaneous tissues and skin of the middle portion of the anterior abdominal 
wall. 
(iii.) Ensiform, a small branch which crosses the front of the ensiform process to anastomose 
with its fellow of the opposite side. It supplies the adjacent muscles and skin. 
(iv.) Hepatic branches of small size pass backwards in the falciform hgament to the liver, 
where they anastomose with branches of the hepatic artery. 
(4) Superior Intercostal Artery (truncus costo-cervicalis, Fig. 556).—The 
superior intercostal artery springs from the back of the second part of the sub- 
clavian artery on the right side and from the first part on the left side. It runs 
upwards and backwards from its origin, over the apex of the pleural sac, to the 
neck of the first rib in front of which it descends, between the first thoracic 
ganglion of the sympathetic cord and the first dorsal nerve, to the first intercostal 
space, where it divides into two branches which are distributed to the upper two 
intercostal spaces. 
Branches.—(«) The profunda cervicis (a. cervicalis profunda).—This branch some- 
times arises from the subclavian artery directly ; but more commonly it springs from the 
superior intercostal at the upper border of the neck of the first rib. It runs backwards, like 
the dorsal branch of an intercostal artery, passes between the first dorsal and last cervical 
nerves, and between the transverse process of the last cervical vertebra and the neck of the 
first rib to the back of the neck, where it ascends between the complexus and the semi- 
spinalis colli muscle to terminate by anastomosing with the deep branch of the princeps 
cervicis artery. It also anastomoses with branches of the ascending cervical and vertebral 
arteries, supplies the adjacent muscles, and sends a spinal branch through the inter- 
vertebral foramen between the last cervical and the first dorsal vertebrae into the spinal 
canal, which anastomoses with the spinal branches of the vertebral and intercostal 
arteries. ; 
(4) Terminal.—The two terminal branches run outwards, one in the first and one 
in the second intercostal space. Each runs near the upper border of its space, passing at 
first between the pleura and the posterior intercostal membrane, and then between the 
as 
