90 ANTHROPOLOGY. 
organs. These arteries sometimes rise from the intercostal, and are very 
irregular in number and size. 
The esophageal arteries are also irregular, generally three or four in 
number. ‘They arise from different parts of the aorta, and send branches 
to the mediastinum.and cesophagus. On the latter, some ascend, some 
descend. The former inosculate with on cervical arteries, the latter with 
the abdominal. | 
The intercostal arteries are usually ten on the left, and nine on the right. 
They arise from the back part of the aorta, pass duliqnely outwards behind 
the pleura, and enter the intercostal spaces; run along the lower edge of 
each rib between the layers of muscles, and, about the middle of the chest, 
divide into an inferior and a superior branch. They both supply the inter- 
costal muscles, and inosculate with the internal mammary and with the 
thoracic arteries. Hach intercostal artery, before entering the intercostal 
space, sends a large dorsal branch backwards to the muscles on the posterior 
part of the trunk. 
Pl. 135, jig. 9, arch of the aorta, with the thoracic artery: *, trachea; 
** branch; *, cesophagus; °, arch of the aorta; °*, innominata; ’, left com- 
mon carotid; *, left subclavian; °, first intercostal; *, thoracic aorta; 
»% oesophageal arteries; * “, posterior bronchial; *, an intercostal; ”, its 
anterior or intercostal branch; ™, its dorsal branch, **, a branch to the 
medulla spinalis. iy. 10, arteries of the spinal marrow, the anterior wall 
of the vertebral canal removed: ’, spinal marrow inclosed in its sheath; 
*, an intercostal artery; *, aspinal artery entering the intervetebral foramen 
and ramifying over the spinal marrow and its sheaths. 
EH. Abdominal Aorta. 
The abdominal aorta commences below the tendinous arch, between the 
crura of the diaphragm in the median line, descends with a slight obliquity 
to the left, and divides at the lower margin of the fourth lumbar vertebra 
into the two iliac arteries. ‘The middle sacral may also be considered as one 
of its terminal branches. It sends off the following branches: the phrenic, 
coeliac axis, superior mesenteric, inferior mesenteric, renal, supra-renal, sper- 
matic, lumbar, and middle sacral. 
1. Tur PHRENIC ARTERIES arise in common or near each other, from the 
fore part of the aorta. They both send branches to the supra-renal capsules 
and to the crura of the diaphragm. The rzght ascends behind the vena cava, 
the left behind the cesophagus. On the diaphragm each divides into an 
external and an internal branch. The former passes towards the cireum- 
ference of the muscle, and inosculates with the internal mammary and the 
inferior intercostals ; the latter encircles the central tendon. 
2. THe Caiiac AXxIs arises from the fore part of the aorta opposite to 
the last dorsal vertebra; it soon divides into three branches. 
a. The gastric artery. This sends branches to the cardiac orifice, to the 
cesophagus, and to the anterior and posterior surfaces of the stomach. 
b. The hepatic artery. This divides ultimately into the right and left 
hepatic arteries. Previous to this division it gives off the superior pyloric 
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