346 A MANUAL OF ANATOMY. 



by the common trunk from the first right intercostal 

 artery. The bronchial arteries supply the lungs, lym- 

 phatic glands (bronchial), oesophagus, and pericardium. 

 (3) The oesophageal, four or five to the oesophagus and 

 mediastinum. (4) The intercostal arteries. There are nine 

 or ten of these distributed to the parietes of the chest. The 

 first and second spaces are supplied by the superior inter- 

 costal branch of the subclavian (seepage 113). The right 

 intercostals are slightly longer than the left, owing to the dis- 

 placement of the aorta to the left of the median line. Their 

 course is alike in all. Each artery runs outward, with the 

 intercostal vein above and the nerve below, upon the exter- 

 nal intercostal muscle, then between the external and inter- 

 nal intercostal muscles, and in the intercostal groove of the 

 rib above ; passing around the chest to the front, it finally 

 anastomoses with the upper of the pair of anterior intercos- 

 tal arteries from the internal mammary. The lower inter- 

 costal arteries anastomose with the musculophrenic branch 

 of the internal mammary and the upper lumbar arteries. 

 Each intercostal artery gives off a dorsal artery to the parts 

 posterior to the chest, and a branch to the spine and cord. 

 Also, a small collateral intercostal artery opposite the angle 

 of the ribs. This artery runs forward along the top of the 

 rib below and between the external and internal intercostal 

 muscles to anastomose in front with the lower of the pair of 

 anterior intercostal arteries from the internal mammary. 

 (5) The pleural, muscular, and mammary (from the third, 

 fourth, and fifth) are small branches from the intercostals. 



The Intercostal Muscles. 



The External. 



Origin. From the lower outer border of the upper eleven 

 ribs external to the tubercles. 



