THE ARTERIES. 



103 



Caliac Axis. 



2 Spermatic. 

 Inferior Mesenteric. 

 8 Lumbar. 

 Sacra Media. 

 2 Common Iliac. 



FIG. 54- 



1f 



the 4th lumbar vertebra. It is divided into the arch, the thoracic aorta, and the 

 abdominal aorta ; and the arch is subdivided into the ascending, 5 transverse, 6 and 

 descending 12 portions. The upper border of the arch is generally situated about 

 an inch below the upper margin of the sternum. The branches of the aorta are,^ 



From the Arch, 2 Coronary .* Left Common Carotid) 

 Innominate? Left StibclavianP- 



From the Thoracic, Pericardiac. (Esophageal. 20 Intercostals. 

 Bronchial. Posterior MediastinaL 



From the Abdominal, 2 Phrenic. 



Gastric. 

 Hepatic. 

 Splenic. 



Superior Mesenteric. 

 2 Supra-renal. 

 2 Renal. 



Describe the Coronary Arteries. They are 2 

 in number, a right and a left, 4 arise from the aorta 

 behind the semilunar valves and run in the ver- 

 tical grooves of the heart, the left artery in front, to 

 supply the tissue of that organ. 



Describe the Innominate. 7 It arises from the 

 summit of the arch of the aorta, is i^ inch long, 

 and divides behind the right sterno-clavicular joint 

 into the Right Common Carotid* and Right Subcla- 

 vian* these arteries on the left side of the body aris- 

 ing directly from the arch of the aorta. 10 n It some- 

 times sends off a Middle Thyroid (artery of 

 Neubauer) which may arise directly from the 

 arch of the aorta. The innominate is sometimes 

 absent, and not infrequently varies in length from 

 an inch to two or more. 



Describe the Common Carotid. Arising differently (see above), the two 

 carotids are similarly described, except that the left is longer and deeper than 

 the right one. Their course is indicated by a line drawn from a point midway 

 between the angle of the lower jaw and the mastoid process to the sterno- 

 clavicular articulation. At the lower part of the neck they are separated only 

 by the width of the trachea, and they are each contained in a sheath of the 

 deep cervical fascia with the internal jugular vein externally and the pneumo- 

 gastric nerve between the artery and vein. On the front of the sheath lies the 

 descendens noni nerve (descending branch of the gth or hypoglossal). The 

 artery lies beneath the inner border of the sterno-cleido-mastoid muscle, and is 

 crossed about its middle by the omo-hyoid muscle and the middle thyroid vein. 



