Lymphatics of the Abdomen Anatomy
The lymphatic vessels and nodes of the abdomen drain the abdominal and pelvic organs as well as the pelvic walls and the lower part of the abdominal wall. (The upper part of the abdominal wall is drained by the internal thoracic and axillary nodes; p. 145.) In addition, the abdominal lymphatics receive lymph from the lower limb, the gonads and the perineum.
Some lymph nodes are situated adjacent to the organs they drain and include those of the liver and spleen and in the hila of the kidneys. The lymphatic vessels draining most of the abdominal organs accompany blood vessels and pass to nodes grouped around the aorta. Often, lymph passes through intermediate nodes situated along the courses of the arteries. Most of the lymph from the abdominal walls and viscera eventually drains into the thoracic duct.
Because of their deep position, most intra-abdominal lymph nodes are not palpable in the living subject, even when enlarged.
The external iliac nodes (Fig. 4.93) receive lymph from the lower limb and perineum via the deep inguinal nodes. In addition, the iliac nodes drain the deeper layers of the abdominal wall below the level of the umbilicus via lymphatic vessels accompanying the inferior epigastric vessels. Lymph from the superficial tissues of the lower abdominal wall reaches the external iliac nodes, having passed first to superficial and then to deep inguinal nodes.
The internal iliac nodes drain the pelvic walls and floor and some of the pelvic organs, including the bladder, lower part of the rectum, prostate and uterus. However, lymph from most of the rectum, sigmoid colon and ovaries drains to the aortic nodes. From the external and internal iliac nodes lymph passes to nodes alongside the common iliac artery (Fig. 4.93) and subsequently to the aortic nodes.
The major abdominal lymphatic vessels and their associated nodes are arranged alongside the aorta (Fig. 4.94). The nodes on each side of the aorta receive lymph from the common iliac nodes, posterior abdominal wall, gonads, kidneys and suprarenal glands, while nodes lying immediately anterior to the aorta drain the digestive organs.
Nodes around the origin of the inferior mesenteric artery drain lymph from most of the rectum and the sigmoid and descending parts of the colon. Nodes lying adjacent to the origins of the superior mesenteric and coeliac arteries drain the spleen, pancreas, liver, stomach, small intestine and the large intestine as far as the splenic flexure.
Efferent lymphatics from the aortic nodes drain into the cisterna chyli (Fig. 4.95). This fusiform sac lies at the level of the upper two lumbar vertebrae, adjacent to the right crus of the diaphragm. It lies behind the right border of the aorta and opens superiorly into the thoracic duct. The duct ascends through the aortic opening of the diaphragm and continues through the thorax to drain into the great veins in the root of the neck (p. 62).
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