ABDOMINAL LYMPHATIC AND LACTEAL VESSELS, 509 



number, clustering- round the external iliac artery, receive the efferent 

 vessels from both deep and superficial inguinal glands. 



The internal iliac lymphatic glands, a numerous series placed 

 on the internal iliac artery, and the sacral glands, placed in the 

 hollow of the sacrum, receive the lymphatics from tlie pelvic viscera 

 and ijarietcs. 



The lumbar lymphatic glands are very large and numerous ; they 

 are placed in front of the lumbar vertebra, around the aorta and vena 

 cava. To tliese proceed the efferent vessels of the glands already men- 

 tioned, as well as those which accompany several of the branches of the 

 abdominal aorta. 



The efferent absorbent vessels which proceed from the lumbar glands 

 progressively increase in size, while their number diminishes, and at 

 length they unite into a few trunks, which, with those of the lacteals, 

 form the origin of the thoracic duct. 



The deep lymphatics of the abdominal wall in part pass along 

 the circumflex iliac and epigastric arteries, to the external iliac glands ; 

 the gi'eater number are directed backwards with the ilio-lumbar and 

 lumbar arteries, and, being joined by the lymphatics from the muscles 

 of the back, pass behind the psoas muscle to the vertebral column, 

 where they enter the lumbar glands. 



The lacteals (vasa lactea, chylifera) commence in the coats of the 

 intestines by a very close plexus, and extend to the thoracic duct, in 

 which they all terminate : they are far more numerous in the small 

 than in the large intestine, so that they abound in the mesentery, 

 and particularly in that of the jejunum and ileum. Two series 

 of absorbent vessels are found along the tube of the intestine, 

 having different positions and directions : those nearest to the outer 

 surface of the intestine run longitudinally in the course of the canal, 

 lying beneath the peritoneal coat, whilst others, placed more deeply 

 between the muscular and mucous coats, run transversely round the 

 intestine, and are directed thence with the arteries and veins along the 

 mesentery, enclosed between the two layers of the peritoneum, (Cruik- 

 shank, " Anatomy of the Absorbent Vessels," p. 1G2.) Sometimes the 

 more superficial absorbents of the intestine are named lymphatics, to 

 distinguish them from the deep set which absorb the chyle from the 

 cavity of the intestine. According to Teichmann (" Das Saugader- 

 system," 1861, p. 75), the two plexuses have no capillary anastomoses, 

 but communicate only through valved vessels : this they do freely. 

 The lacteals, having entered the mesentery, take the course of the 

 blood-vessels, and pass through successive sets of numerous mesenteric 

 lymphatic glands. 



The mesenteric glands vary in number from a hundred and thirty 

 to a hundred and fifty ; and in the healthy state are seldom larger than 

 an almond. They are most numerous in that part of the mesentery 

 which corresponds with the jejunum ; and they seldom occur nearer to 

 the attached iDorder of the intestine than two inches. Small gland.s 

 in limited numbers are also disseminated irregularly between the folds 

 of the peritoneum connected with the large intestines. 



Having passed through these glands, the lacteals gradually unite as 

 they approach the attached border of the mesentery, and so become 

 diminished in number but increased in size, until at length, near the 

 root of the superior mesenteric artery, only two or three trunks remain, 



