For the portions of the colon distal to the splenic flexure, the parasympathetic innervation is from S2-S4, via the pelvic splanchnic nerves and the inferior hypogastric plexus. Recall that arterial blood supply to the colon also had a "transition" near the splenic flexure. In addition to this information from the previous lab, there is one small point. So, for example, they will pass through, but not synapse within, the celiac ganglion. Parasympathetic nerves usually synapse within the target tissue.
On the other hand, the parasympathetic fibers that innervate the distal portion of the colon come from S2-S4 via the pelvic splanchnics.
They do not follow along the same paths as the sympathetic fibers, which, in this case, go through the inferior mesenteric plexus. Branches of the pelvic splanchnic nerves reach the hindgut by passing up over the left pelvic brim and through the fusion fascia to reach the splenic flexure, and the descending and sigmoid colon. Of course, pelvic splanchnic nerves also distribute to pelvic viscera, such as the rectum, but we can save that story for the pelvis.
When present, all of the lymph trunks draining the abdomen and lower limbs dump into it, as well as the most inferior intercostal lymph trunks. When it is not present, these trunks simply empty into the thoracic duct. See the pages indicated above for good diagrams of the general pattern of lymphatic drainage of the body.
Especially important in the abdomen is the intestinal lymph trunk, which carries all of the fat from those double cheeseburger combo meals from the small intestine to the thoracic duct.
It runs under the psoas major muscle , emerging at the muscle's lateral border to run over the quadratus lumborum muscle. The iliohypogastric nerve provides motor innervation to the muscles of the lower abdominal wall and sensory innervation to the skin of the lower abdominal wall, upper hip and upper thigh.
It runs under the psoas major muscle , emerging at the muscle's lateral border to run over the quadratus lumborum muscle , inferior to the iliohypogastric nerve.
The ilioinguinal nerve provides motor innervation to the muscles of the lower abdominal wall and sensory innervation to the skin of the lower abdominal wall and the anterior labium majus OR scrotum. In a significant number of cases the ilioinguinal is combined with the genitofemoral nerve. It pierces the psoas major muscle at about the level of L3 or L4. The genitofemoral nerve provides motor innervation to the cremaster muscle via its genital branch and sensory innervation to the skin of the anterior labium majus OR scrotum via its genital branch and the upper medial thigh via its femoral branch.
It runs under the psoas major muscle , emerging at the muscle's lateral border to run over the iliacus. The lateral femoral cutaneous nerve provides sensory innervation to the skin of the lateral thigh. It runs along the medial border of the psoas major muscle. The obturator nerve provides motor innervation to the muscles of the medial thigh: the adductor longus m. It provides sensory innervation to the skin of the lower medial thigh.
It runs inferiorly, along the border between the psoas major muscle and the iliacus muscle. It supplies motor innervation to the sartorius, rectus femoris, vastus lateralis, vastus intermedius, vastus medialis, and pectineus muscles , while providing sensory innervation to the skin of anterior thigh.
The white rami communicantes are only found as low as the L2 or L3 level. Inferior to that there are no sympathetic neuron cell bodies in the spinal cord, and are therefore no sympathetic fibers emerging from the cord into the spinal nerves. Since the white rami communicantes conduct fibers from the spinal nerve to the ganglia, they are unnecessary below L2 or L3.
But, there are sympathetic fibers in the chain that have traveled from points superior, so there are gray rami communicantes , conducting fibers from the ganglia back onto the spinal nerve, along the chain's entire length. There are four sites of porto-caval anastomosis described: distal esophageal veins, rectal venous plexus, paraumbilical veins, and posterior abdominal wall veins. These usually appear in roughly this order when portal hypertension, usually due to liver cirrhosis, causes pressure within the portal veins to increase because it has difficulty in passing through the liver sinusoids.
The portal venous blood then finds alternate routes back into the caval venous system, bypassing the liver. In rough order of appearance in the progression of this condition:. Retrograde passage of blood from the portal vein into these distal esophageal veins causes esophageal varicies, enlarged veins within the walls of the esophagus. If these rupture, the blood will be digested and produce black feces. It is commonly thought that retrograde flow of blood down the superior rectal tributaries engorge the veins in the anal columns and cause internal hemorrhoids.
However, it has recently been shown that it is more accurate to describe these enlarged veins as within the rectal venous plexus within the walls of the rectum. The paraumbilical veins have connections to veins draining the anterior abdominal wall, and retrograde blood in the paraumbilical veins will enlarge the anterior abdominal wall veins.
The superficial veins of the anterior abdominal wall will be most visible, of course, and their engorgement, radiating from the umbilicus, is called caput medusa after Medusa, the woman with the snake hair-do. The portal tributaries of the secondarily retroperitoneal organs duodenum, pancreas, ascending and descending colon can form anastomoses with veins of the posterior abdominal wall, the lumbar veins, that ultimately drain into the inferior vena cava usually.
Cultural enrichment: Check out these sections from the version of Gray's Anatomy of the Human Body! Some of the terms are of course out-of-date, but the illustrations are timeless.
It receives 2 or 3 major calyces, each of which receives 2 or 3 minor calyces. The minor calyces are indented by the renal papillae, which are the apices of the renal pyramids. A pyramid and its cortical tissue comprise a lobe. Each kidney is covered by a two-layered capsule and is surrounded by perinephric fat, Gerota's fascia, Zuckerkandl fascia, and paranephric fat. The entire area immediately involving the kidneys is considered the retroperitoneum.
Excerpt The kidneys are bean-shaped organs, with medial concavity and lateral convexity, weighing anywhere from to g in males and about to g in females. The following are the kidneys relative to surrounding organs: Superiorly, on top of each kidney and separated by renal fascia, are the suprarenal glands adrenal glands , the right pyramidal suprarenal gland oriented apically on the right kidney and the left crescentic suprarenal gland oriented more medially on the left kidney The right kidney is posterior to the ascending colon, the second part of the duodenum medially, and the liver, separated by the hepatorenal recess The left kidney is posterior to the descending colon, its renal hilum lateral to the tail of the pancreas, superomedial aspect adjacent to the greater curvature of the stomach, and left upper pole adjacent to the spleen and connected by splenorenal ligaments Posteriorly, the diaphragm rests over the upper third of each kidney with the 12th rib passing posteriorly over the upper pole.
Publication types Review. The medial-facing hila are tucked into the sweeping convex outline of the cortex. Emerging from the hilum is the renal pelvis, which is formed from the major and minor calyxes in the kidney.
The smooth muscle in the renal pelvis funnels urine via peristalsis into the ureter. The renal arteries form directly from the descending aorta, whereas the renal veins return cleansed blood directly to the inferior vena cava. The artery, vein, and renal pelvis are arranged in an anterior-to-posterior order. The renal artery first divides into segmental arteries, followed by further branching to form interlobar arteries that pass through the renal columns to reach the cortex.
The interlobar arteries, in turn, branch into arcuate arteries, cortical radiate arteries, and then into afferent arterioles. The afferent arterioles service about 1. As mentioned earlier, these glomerular capillaries filter the blood based on particle size. After passing through the renal corpuscle, the capillaries form a second arteriole, the efferent arteriole. These will next form a capillary network around the more distal portions of the nephron tubule, the peritubular capillaries and vasa recta, before returning to the venous system.
As the glomerular filtrate progresses through the nephron, these capillary networks recover most of the solutes and water, and return them to the circulation. Since a capillary bed the glomerulus drains into a vessel that in turn forms a second capillary bed, the definition of a portal system is met. This is the only portal system in which an arteriole is found between the first and second capillary beds.
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