THE VEINS. 



117 



FIG. 60. 



Vence Basis Vertebrarum, empty into the anterior longitudinal. 

 Longitudinal, in two plexuses, anterior and posterior, running the whole 



length of the spinal canal. The posterior join the dorsi-spinal veins, the 



anterior empty into the vertebral, intercostal, lumbar, and sacral veins in 



their various regions. 

 Dorsi-spinal, form a plexus around the 



spines, processes, and laminae of all the 



vertebrae. They empty into the vertebral, 



intercostal, lumbar, and sacral veins in 



their respective regions. 

 Describe the Subclavian Vein. It is the 

 continuation of the axillary, extending from 

 the outer marg'n of the 1st rib to the sterno- 

 clavicular articulation, where it unites with the 

 internal jugular to form the innominate vein. 

 At the angle of junction enters the thoracic 

 duct on the left side of the body and the right 

 lymphatic duct on the right side. In its course 

 it receives the external and anterior jugular 

 veins and a branch from the cephalic. 



Describe the Venae Innominatse. The 

 two innominate veins are each formed by the 

 union of the subclavian and internal jugular, 

 and unite below the 1st costal cartilage to 

 form the superior vena cava. The Right In- 

 nominate* is about I ^ inch long, and receives, 

 besides its constituent branches, the right in- 

 ternal mammary, right inferior thyroid, and 

 right superior intercostal veins. The Left In- 

 nominate 1 ' is about 3 inches long, and in its 

 course it receives the vertebral, inferior thy- 

 roid, internal mammary, and superior inter- 

 costal veins of the left side. 



Describe the Superior Vena Cava. 1 It is 

 a short trunk about 2^ or 3 inches in length, formed by the union of the venae 

 innominatae, and receives all the blood from the upper half of the body, termi- 

 nating in the right auricle of the heart. It is half covered by the pericardium, 

 and receives the vena azygos major and small pericardiac and mediastinal veins. 



Name the Principal Veins of the Lower Extremity. They are in two 

 sets, superficial and deep. The deep are the Vena Comites of the anterior and 



