THE TERMINAL LYMPH VESSELS. 863 
sometimes the thoracic portion is broken up into a series of anastomosing channels. 
The widest portion of the tube is usually the receptaculum, but oce casionally this 
dilatation is entirely absent. The duct is provided with several valves, formed by 
semilunar folds of the inner coat, arranged in pairs, and the most perfect of these 
is situated at the orifice of communication with the innominate vein. 
Relations.—In the abdomen the receptaculum chyli lies in front of the upper two 
lumbar vertebrae, between the aorta on the left and the vena azygos major and the right 
crus of the diaphragm on the right. In the posterior mediastinum it is separated from 
the vertebral column and the anterior common ligament, by the right aortic intercostal 
arteries and the transverse parts of the small azygos veins; it is covered in front in the 
lower part of its extent by the right pleural sac, and in the upper part by the esophagus ; 
to its right is the vena azygos major, and to its left the descending aorta. In the 
superior mediastinum it passes forwards from the vertebral column, and it is separated 
from the left longus colli muscle by a mass of fatty tissue ; in front of it, in the lower part 
of this region, is ‘the terminal part of the arch of the aorta, and at a higher level the left 
subclavian artery. As the duct enters the root of the neck it passes behind the left 
common carotid artery, whilst to its right and somewhat in front is the cesophagus, and 
to its left the left pleura. 
At the root of the neck it arches outwards above the apex of the pleural sac and the 
first part of the left subclavian artery. It passes in front of the vertebral artery and 
vein, the root of the inferior thyroid artery, the inner border of the scalenus anticus and 
the phrenic nerve, and behind the left carotid sheath and its contents. 
Tributaries.—The receptaculum chyli generally receives five tributaries. (1) The 
common intestinal lymphatic trunk (truncus intestinalis), which conveys lymph from 
the lower and anterior part of the liver, the stomach, the small intestine, the spleen, 
and the pancreas. (2) Two common lumbar lymphatic trunks (trunci lumbales), one 
on each side; they carry lymph from the lower extremities, from the deep portions 
of the abdominal and pelvic walls, the large intestine and the pelvic viscera, and 
from the kidneys and suprarenal capsules ; and (5) two descending lymphatic trunks, 
one on each side, each of which is formed by the efferent vessels from the corre- 
sponding lower intercostal glands; these descend to the receptaculum through the 
aortic opening of the diaphragin. 
In its course through the posterior mediastinum the thoracic duct receives 
efferents from some of the lower intercostal glands on the left side, a few from the 
upper and back part of the liver, and others from the posterior mediastinal glands. 
In the superior mediastinum the vessels which open into it are derived from 
the upper left intercostal glands, the left half of the heart and pericardium, and 
the left lung and pleura. It also receives some of the efferents of the superior 
mediastinal and sternal glands. 
At the root of the neck, just before its termination, it receives the efterents 
from the glands of the left upper extremity, which frequently unite to form a com- 
mon trunk (truncus subclavius), and the left common jugular lymphatic (truncus 
jugularis), which conveys the lymph from the left side of the head and neck. 
Right Lymphatic Duct.—The right lymphatic duct (ductus lymphaticus 
dexter, Fig. 596) is a short trunk, from halt to three-quarters of an inch 1 (12 to 
17 mm.) in leneth, which hes at the right side of the root of the neck along the inner 
border of the scalenus anticus. It is formed by the confluence of the right common 
jugular lymphatic vessel and the efferent vessels from the glands of the right 
upper extremity ; 1t also receives efferents from the intercostal glands of the upper 
intercostal spaces on the right side and from the visceral thoracic glands on 
the right side. It thus receives lymph from the right side of the head and neck, 
the right upper limb and the right side of the trunk, including the upper part of 
the thoracic wall, the right lune and pleura, the right half of the heart and peri- 
cardium, the right side of the diaphragm, and the upper surface of the liver. 
THE LYMPHATIC VESSELS AND GLANDS OF THE HEAD AND NECK. 
The lymphatic vessels of the head and neck form two groups, (1) the 
intracranial and (2) the extracranial. 
