THE LYMPH VESSELS AND GLANDS 643 



The metatarsal and digital veins resemble in general the corresponding vessels 

 of the fore limb. 



The Lymph Vessels and glands 



The cistema chyli is large and fusiform. The thoracic duct may be single 

 throughout, but often divides anteriorly into two branches, which may then unite 

 and form a dilatation which receives the left tracheal duct and the vessels from the 

 fore limb. The primitive plexiform arrangement persists in varying degree. The 

 duct terminates in the left brachiocephalic vein. 



The tracheal ducts accompany the internal jugular veins. The right duct 

 opens into the right Ijrachiocephalic vein. 



The submaxillary lymph glands (Fig. 486) are commonly three in number on 

 each side. They are situated in the angle between the masseter and the submaxil- 

 lary salivary gland, in relation to the external maxillary vein and covered only 

 by the skin and panniculus. The numl^cr may be reduced to two or one with a 

 corresponding increase in size. 



A small round parotid or auricular lymph gland is situated superficially be- 

 tween the upper part of the post (^ior border of the masseter and the parotid gland. 



The phar5mgeal (or retropharyngeal) lymph glands, one or two in numl)er 

 on each side, lie on the pharynx chiefly under cover of the submaxillary salivary 

 gland. 



The prescapular or superficial cervical lymph glands lie on the serratus magnus 

 at the anterior border of the sui)ras]:)inatus, embedded in a mass of fat. Usually 

 two or three are present on each side, but there may l)e only one. They are oval 

 and are about an inch long in a dog of medium size when two are present. 



The axillary lymph gland lies in a mass of fat on the inner face of the lower 

 part of the teres major. It is discoid. 



The cubital lymph gland is inconstant. It is situated on the deep face of 

 the long head of the triceps or on the latissimus dorsi. 



The mediastinal lymph glands are small and quite variable in arrangement. 

 Usually one or two glands are found on the course of the internal thoracic ves- 

 sels at the second segment of the sternum. 



The bronchial lymph glands are commonly four in number. The largest is 

 situated in the angle of divergence of the chief bronchi, two lie on the origin of 

 the right apical bronchus, and the fourth is between the aortic arch and the anterior 

 face of the left bronchus. They are commonly pigmented. 



The lumbar lymph glands are small. 



The mesenteric lymph glands are represented chiefly by a long flattened mass 

 (formerly known as the pancreas Aselli) which lies in the mesentery along the 

 course of the anterior mesenteric artery and vein. It is succeeded by three or 

 four glands which lie along the portal vein and appear to receive vessels from 

 the stomach, spleen, liver, pancreas, and great omentum. A few very small 

 nodes occur along the colon. 



The iliac lymph glands are relatively large and are situated at the termination 

 of the aorta and the origin of the iliac arteries. Commonly four are present. Of 

 these, the two largest lie on the psoas minor on each side in relation to the aorta 

 and vena cava respectively. The other two are in the angle of divergence of 

 the internal iliac arteries. 



The superficial inguinal lymph glands are situated in the subcutaneous fat 

 behind the external inguinal ring. They are relatively large, especially when there 

 is only one on each side ; two smaller ones may be found instead. 



The popliteal lymph gland — usually unique, but sometimes double — lies in 

 a pad of fat on the upper part of the gastrocnemius between the biceps femoris 

 and semitendinosus. It may project back so as to be superficial and palpable. 



