Small Intestine Flashcards
How long is the small intestine?
7 meters
Where does absorption of nutrients occur almost entirely?
Small intestine
What does the large intestine mainly absorb?
Water
What is the duodenum?
C-shaped tube that surrounds the head of the pancreas
How long is the duodenum?
25 centimeters
What is the shortest and widest part of the small intestine?
Duodenum
What part of the duodenum runs to the right?
Superior (first) part
What is the beginning of the superior part of the duodenum called?
Duodenal cap (ampulla)
Why is the duodenal cap (ampulla) radiogically significant?
Trappage of gas occurs here and is visible on x-ray
What part of the duodenum contains the junction of the foregut and midgut where the bile duct and pancreatic duct empty?
Descending (second) part
What is the longest part of the duodenum that runs to the left, anterior to the inferior vena cava, and vertebral column?
Inferior or horizontal (third) part
What part of the duodenum ascends to the left of the aorta and terminates at the duodenojejunal flexure?
Ascending (fourth) part
What is significant about the distal end of the four part of the duodenum?
Can also be intraperitoneal
What is the fibromuscular band which extends from the diaphragm to the duodenojejunal flexure called?
Suspensory muscle (ligament) of the duodenum
The duodenum is entirely retroperitoneal except what part?
Duodenal cap (freely moveable)
What vessels pass anterior to the third part of the duodenum?
Superior mesenteric artery and vein
What is the blood supply to the duodenum?
Superior pancreaticoduodenal, supraduodenal, and inferior pancreaticoduodenal arteries
The superior pancreaticoduodenal artery is a branch from where?
Gastroduodenal artery
The supraduodenal artery is a branch from where?
Gastroduodenal artery
The inferior pancreaticoduodenal artery is a branch from where?
Superior mesenteric artery
What does the inferior pancreaticoduodenal artery specifically supply?
Third and fourth parts of the duodenum
What is the innervation of the duodenum?
Autonomic fibers from the celiac and superior mesenteric plexuses
What is a duodenal ulcer?
Mucosa in the duodenum is eroded to form a crater-like depression
Where are duodenal ulcer most commonly found and why?
In the duodenal cap due to its proximity to the pyloric sphincter, which is the most acidic area
What other organs can be damaged by a perforated duodenal ulcer due to their proximity?
Liver, pancreas, and gall bladder
What is a perforated duodenal ulcer?
When the contents escape into the peritoneal cavity causing peritonitis
What is the pathway for fluid traveling with a perforated duodenal ulcer?
Subhepatic recess to the right paracolic gutter to the right iliac fossa
Erosion of what artery by a perforated duodenal ulcer can result in severe hemorrhage?
Gastroduodenal artery
What is the chiropractic note on duodenal ulcers?
Midthoracic subluxations are associated with them, and the greater splanchnic nerve supplies sympathetic innervation to the duodenum above the entrance of the common bile duct
The jejunum makes up what part of the small intestine?
Proximal 2/5 distal to the duodenum
The ileum makes up what part of the small intestine?
Distal 3/5 of the small intestine
The jejunum lies mostly in what quadrant of the abdomen?
Left upper quadrant
The ileum occupies what quadrant of the abdomen?
Right lower quadrant
What is the location where the ileum joins the cecum called?
Ileocecal junction
Are the jejunum and ileum retro or intraperitoneal?
Intraperitoneal and therefore mobile
The jejunum and ileum are suspended from the posterior abdominal wall by what?
Mesentery
What are the vasa recta?
Straight terminal branches of the arteries which travel through the mesentery to supply the small intestine
Where are the most nutrients specifically absorbed in the GI tract?
Jejunum
What are the circular folds found within the small intestine called?
Plicae circulares
Where are the plicae circulares found in the SI?
Mucosa
What is the purpose of the plicae circulares?
Increase surface area for absorption and slow the passive of material
What are the Peyer’s patches of the SI?
Aggregations of lymphoid tissue found within its walls
What is the color of the jejunum and ileum, respectively?
Dark red, pale pink
What is the vascularity of the jejunum and ileum, respectively?
Greater, lesser
Why is the jejunum more vascular than the ileum?
More blood flow to facilitate absorption
What is the diameter of the jejunum and ileum, respectively?
Larger, smaller
Why does the jejunum have a larger diameter than the ileum?
Because it has more surface area
What are the walls like of the jejunum and ileum, respectively?
Thicker, thinner
What are the vasa recta like of the jejunum and ileum, respectively?
Longer, shorter
What is the mesenteric fat amount of the jejunum and ileum, respectively?
Less, more
What are the plicae circulares like of the jejunum and ileum, respectively?
Tall, many; short, few
In which part of the small intestine are Peyer’s patches absent and present?
Absent in the jejunum and present in the ileum
Why are there more Peyer’s patches found in the ileum?
Due to higher bacterial count in that area
What is the blood supply to the jejunum and ileum?
Jejunal and ileal branches of the superior mesenteric artery
What is the innervation of the jejunum and ileum?
Autonomic fibers from the superior mesenteric plexus
What part of the small intestine is responsible for absorbing fat-soluble viitamins, B12, and bile salts?
Ileum
What is a common malformation of the digestive tract?
Ileal (Meckel’s) Diverticulum
Ileal (Meckel’s) Diverticulum is a remnant of what embryologic feature?
Vitelline duct
What is Ileal (Meckel’s) Diverticulum?
A fingerlike pouch that projects from the distal ileum made of all layers of the ileum and may contain gastric or pancreatic tissue, as well
What is the danger of the Ileal (Meckel’s) Diverticulum containing gastric tissue?
Gastric tissue can release acid
When the gastric tissue of Ileal (Meckel’s) Diverticulum releases acid, what can occur?
The diverticulum often becomes inflames, mimicking appendicitis
What condition of the GI tract mimics appendicitis?
Ileal (Meckel’s) Diverticulum
What is Crohn’s Disease?
An inflammatory bowl disease that can affect any part of the digestive tract
Where does Crohn’s Disease usually affect?
Distal ileum and adjacent colon
What is unique about Crohn’s Disease?
It can affect all layers of the intestine and results in thickening and ulceration of the affected segment
What results from Crohn’s Disease?
Pain, diarrhea, and malabsorption
What is the etiology of Crohn’s Disease?
Unknown, but possibly related to stress or autoimmune disease
What type of radiographic appearance does Crohn’s Disease show?
“Cobblestone”
What is the chiropractic note on Crohn’s Disease?
Subluxations of the lower thoracic may affect gut motility which is controlled by the autonomic nervous system (vagus, greater and lesser splanchnic nerves)
