GI Flashcards
The foregut contains? (7)
Esophagus, Fundus, Body, Antrum of the stomach, pylorus, duodenal bulb, proximal descending duodenum
The Midgut contains?
Distal descending duodenum, transverse duodenum, ascending duodenum, jejunum, ileum, cecum, Ascending and proximal transverse colon
The Hindgut contains?
Distal transverse colon, Descending colon, sigmoid colon, and rectum.
Explain the embryological rotation and fixation of the foregut, midgut, and hindgut
The foregut rotates clockwise, the midgut rotates counterclockwise. Then the bowel is fixerd into position, either intra or retroperiotoneal.
Normally the stomach and duodenal bulb are intraperiotneal/extraperiotneal? And the Descending and transverse duodenum are retroperitoneal/intraperitoneal?
Stomach and duodenal bulb are normally intraperitoneal
Descending and transverse duodenum are retroperitoneal.
The Jejunum and ileum are intra/extraperitoneal?
Intraperitoneal.
Describe the normal positioning of the cecum and large intestines
The cecum can be intra or retroperitoneal. The ascending colon is retroperitoneal and the transverse colon is intraperitoneal. The descending colon is retroperitoneal, the sigmoid colon is intraperitoneal and the rectum is extraperitoneal.
Together the ascending colon, descending, and rectum are extra or retroperitoneal
The transverse and sigmoid colon are intraperitoneal.
The cecum can be extra or intra
If ligament of treitz is not present what could this mean?
There was a malrotation in the formation of the intestines. All small bowel ends up on the right side of the abdomen instead of where they are supposed to be.
Intestinal malrotation with midgut volvulus presents with?
Presents with billius vomiting. Obstruction is distal to where the bile duct enters the duodenum.
Complex folding during development results in what?
Creates the peritoneal cavity and the subcomponents of the lesser sac (omental bursa) and the greater sac)
The greater omentum is created from the greater curve of the stomach
The Vitelline duct has what clinical significance?
This is a remnant of the yolk stalk that is in the area of the umbilicus and attached to the small bowel (in 2% of population). It can persist as Meckel’s diverticulum and become inflammed, hemorrhage, intusscept, obstruct or ulcerate
Groin is a weak area in the anterior abdominal wall secondary to?
Secondary to the descent of the gubernaculum - inguinal hernias.
Inguinal hearnias result from?
Weakness in the abdominal wall secondary to the gubernaculum and the descent of the testes and the round ligament.
What does the solar plexus contain?
There are extensive nerve plexes that supply the abdomen. - Solar plexus contains
Celiac ganglia and plexus
Prevertebral plexus
Superior and inferior hypogastric PP
The abdominal viscera have extrinsic and intrinsic components of the nervous system.
Function of the extrinsic system in the gut?
Involves sensory and motor nerves that communicate with the CNS - visceral afferent and visceral efferent (SNS and PSNS) fibers
PSNS innervation to the abdominal GIT via vagus nerve (foregut and midgut) and the Pelvic splanchnic nerve (hindgut)
SNS innervation via the splanchnic nerve.
Function of the intrinsic system of the gut?
Involves regulation of the digestive tract by a generally self sufficient network of sensory and motor neurons.
These work with coordinated contraction and relaxation of intestinal smooth muscle (peristalsis) and regulation of gastric secretion and blood flow.
Local neuronal circuit in wall of GI - myenteric and submucosal plexes
Generally independent but can be modified by SNS and PSNS.
Splanchnic nerve function?
Sympathetic fibers to the thoracic, lumbar, and sacral splanchnic nerves to prevertebral plexus.
Parasympathetic fibers to the pelvic and sacral splanchnic nerves from inferior hypogastric plexus (pelvic plexus)
The Preverteral plexus recieves?
PSNS fibers from visceral afferents from Vagus N
SNS and visceral afferents from the thoracic and lumbar splanchnic nerve
PSNS fibers from pelvis splanchnic nerves to the inferior hypogastric plexus.
The celiac artery supplies
Supplies the foregut in the abdomen - esophagus, to proximal duodenum inferior to major duodenal papilla.
The superior mesenteric artery supplies?
The midgut (lower L1) duodenum distal to the major papilla to the proximal 2/3 of the transverse colon
All venous drainage from the GI tract passes through?
Passes through the liver. Note, there are anastomoses with the systemic venous circulation - this is where the collaterals form when there is portal hypertension
The inferior mesenteric artery supplies?
The supplies the hindgut, the distal 1/3 of the transverse colon to the superior part of the rectum.