Descriptive anatomy.— I now proceed to describe the exact course which the lymphatic vessels take in the different parts of the body,. the position and number of the absorbent glands which they traverse, and the precise direction, mode of commencement, and termi nation of the two principal trunks, into they pour their contents.
This part of our subject, the descriptive anatomy, neither requires nor admits of that rigid exactness which is absolutely necessary in tracing out the ramifications of the blood vessels. In the first place, the surgeon, in the performance of his operations and in the treat ment of wounds, scarcely finds it necessary to take the lymphatic vessels into consideration.
, To relieve the stricture in strangulated femoral hernia, he unsparingly divides the principal lymphatics and glands in the inguinal region. In the next place these vessels vary so much in number, and consequently in position in different individuals, while there exist so many parts, where their presence is rather presumed than demonstrated, that a general outline of their course is all that can be re quired or depended upon. In the distribution of these vessels two principal objects are spe cially provided for ; the conveyance of the lymph to its appropriate glands, and after wards from them to the two trunks of the sys tem. We, consequently, first notice an evident tendency of the vessels from the structures in which they take origin towards the glands which intervene between them and the trunks of the system ; secondly, their necessary course from these glands to the trunks themselves.
With this key to the distribution of these vessels, I propose to describe, first, the posi tion of the glands, then to treat of the trunks of the system ; and, lastly, having these two fixed points, to trace the vessels throughout their course.
In the lower extremities the conglobate glands are chiefly found in the inguinal region, where they are divided into a superficial and deeper seated cluster ; a few small glands are situated in the popliteal space surrounding the bloodves sels. We rarely meet with one between the popliteal space and the inguinal region, and they are only occasionally met with below the knee, and then isolated and extremely small. In the upper extremity the large and clustered lym phatic glands are only found in the axillary space; a single gland is generally located just above the internal condyle of the humerus ; below this point a distinct gland is rarely met with.
In the cervical region the principal lympha tic glands are situated in two cellular intervals, found at the upper part between the omo-hyoid and stemo-cleido-mastoid muscles, and below between the latter muscle and the trapezius. The glands in these positions are ranged in a line so as to form a sort of chain of glands, hence the term glandulw concatenate: as applied to them.
On the head and face the glands are few, small, and isolated. One may be pretty con stantly met with behind the ear over the mas toid process of the temporal bone, another in front of the ear in the neighbourhood of the parotid gland. One or two will be found under the margin of the lower jaw, both in the median line and also more laterally situated. A small lymphatic gland will usually be distin guished amorist the numerous but small buccal and labial glands.
In the cavity of the cranium no lymphatic glands have been discovered, but in the abdo minal and thoracic cavities they are very nume rous. In the abdomen they are chiefly situated in the neighbourhood of the larger bloodvessels. In the pelvic region they form clusters, or rather chains of glands accompanying the external, in ternal, and common iliac vessels, and in the lumbar region they are similarly arranged on either side of the aorta, as high as the point of origin of the superior mesenteric artery.
The absorbent glands which intercept the lacteals in their course towards the rcceptaculurn chyli are large and numerous; they are situ ated between the folds of the mesentery, and accompany the trunk and some of the branches of the superior mesenteric artery ; they are usually termed mesenteric glands. The remain ing lymphatic glands of the abdominal viscera, though numerous, are smaller and more isolated ; they will generally be found close to the arteries of the viscera to which they belong, and conse quently between the folds of the peritoneum. Of this description may be considered those accompanying the hepatic and splenic vessels : the coronary and gastro-epiploic arteries of the stomach, the small glands of the mesocolon or epiploon, those associated with the renal or spermatic arteries.