L21- Hindgut Flashcards
What is the major artery supplying the hindgut?
inferior mesenteric artery
What viscera are included in the hindgut?
- distal transverse colon
- descending colon
- sigmoid colon
- rectum
- proximal anus
What is the mesentery off of the sigmoid called?
The sigmoid mesocolon
What is the junction between the rectum and sigmoid called? What is no longer visible at this point on the colon?
- The rectosigmoid junction
- tenia coli no longer visible
What are fistulae?
Patent connections when developmentally connected structures fail to disconnect
Where does the inferior mesenteric artery arise?
From the abdominal aorta at the L3 level
What are the main branches of the inferior mesenteric artery
- left colic artery
- sigmoid artery (2-4)
- superior rectal artery
What is the major vein of the hindgut?
The inferior mesenteric vein (parallels the arteries, as do the left colic, sigmoid and superior rectal)
What are the three major tributaries to the hepatic portal system?
- splenic vein
- superior mesenteric vein
- inferior mesenteric vein
- also contributions from the right and left gastric veins
The superior rectal vein and Inferior Mesenteric Vein are part of what system?
The portal system
The middle and inferior vein to the internal iliac are part of what system?
The caval system
What are the hidden retroperitoneal varices?
Retroperitoneal portions of the GI may drain via lumbar veins directly to the IVC -can also drain through the portal system
What is the pathway for the lymphatics of the hindgut?
Inferior mesenteric and lumbar lymph nodes –> chyle cistern –> thoracic duct
Sympathetic preganglionic fibers originate from where?
T1-L2
Sympathetics to the body wall synapse where?
In the paravertebral ganglion and exit via rami
What do the sympathetics of the abdomen cause? Where do these nerves originate?
- Inhibit peristalsis, reduce blood flow via vasoconstriction
- originate from lateral horn of T5-L2
Where do the sympathetics to the abdominal viscera synapse?
Exit the paravertebral ganglia via abdominopelvic splanchnic nerves -synapse on prevertebral ganglia -travel to target organs on blood vessels
What is the splanchnic nerve to the foregut called?
Greater splanchnic nerve (T5-T9)
What is the splanchnic nerve to the midgut called?
Lesser splanchnic nerve (T10-T11)
What is the splanchnic nerve to the kidneys called?
Least splanchnic nerve (T12)
What are the splanchnic nerve to the hindgut and pelvis called?
Lumbar splanchnic nerves (T12-L2)
What are the prevertebral ganglia of the foregut, superior mesenteric, inferior mesenteric called?
- Foregut: Celiac (greater splanchnic nerves)
- Midgut: Superior mesenteric (lesser/least splanchnic nerves)
- Hindgut: Inferior mesenteric (lumbar splanchic nerves)
Where do parasympathetic fibers synapse?
In the ganglia in walls of target organs (body walls have no parasympathetics)
Preganglionic fibers: cranial nerves or S2-S4
What are the functions of parasympathetics in the abdomen?
Stimulate peristalsis of abdominal organs
What nerve provides the parasympathetics of the foregut and midgut?
Vagus (CN X)
What nerve provides the parasympathetics of the hindgut?
Pelvic splanchnic nerves from S2-4
Which vagus nerve can you find anteriorly? Which is posterior to the esophagus?
- Anterior- Left vagus
- Posterior- Right vagus (travel with esophagus to abdomen)
What pathway does the sensation of pain follow in the foregut/midgut?
The sympathetic pathway backward (thoracic, lumbar or sacral splanchnic nerves)
What pathway does the sensation of pain follow in the hindgut?
The parasympathetic pathway backward (pelvic splanchnic nerves)
What does the non-pain sensation follow in the foregut and midgut?
The parasympathetic backward (vagus)
What pathway does the non-pain sensation follow in the hindgut?
The parasympathetic pathway backward (pelvic splanchnic nerves)
What is referred pain?
Visceral pain interpreted as somatic as they both enter the posterior horn -(when parietal peritoneum/pleura get inflamed the pain becomes sharp and localized as this has a somatic sensation innervation)
