Abdomen II Flashcards
What is the longest part of the Gastrointestinal Tract?
Small intestine
Where does the small intestine extend begin and end?
It extends from the pylorus of the stomach to the ileocecal junction
Divisions of the small intestine
Duodenum, Jejunum and the Ileum
Describe the shape and location of the duodenum and the organ that it surrounds.
- It is a C-shaped tube and surrounds the head of the Pancreas.
- It is the shortest, widest, and most fixed part of the small intestine
- The duodenum and the pancreas lie at the junction between the foregut and the midgut and receive blood from the Celiac Trunk + SMA
What connects the duodenum to the liver (externally to these organs)?
The hepatoduodenal ligament of the lesser omentum
The 4 parts of the Duodenum
(1) L1- Duodenal cap- often affiliated with duodenal ulcers. Attachment for hepatoduodenal ligament. Retroperitoneal begins after the first 1-2 inches.
(2) Descending- L2- L3 Receives the major duodenal papilla (opening of the bile duct and main pancreatic duct) and the minor duodenal papilla (the opening of the accessory pancreatic duct)
(3) Inferior- L3- Crosses inferior Vena Cava and Aorta and is crossed by SMA and SMV
(4) Ascending- Ascends back up to left of L3-L2- Tethered by suspensory ligament at duodenojejunal flexure
Location and functioning of the Pancreas
Endocrine (insulin/glycogen) + Exocrine (digestive enzymes)
Located across the posterior abdominal wall, and extends from the duodenum to the spleen
The 4 parts of the Pancreas
(1) Head- lies in the C-shaped concavity of the duodenum. UNICATE is a finger like extension of the head where the SMA and SMV pass anteriorly. From here they go to supply the small intestine.
(2) Neck- lies anterior to the beginning of the portal vein where the splenic vein and SMV join to form the portal vein– VERY IMPORTANT
(3) Body- Forms the major portion of the stomach bed. Splenic artery runs along its upper border and the splenic vein runs posterior to it.
(4) Tail- Ends in the splenorenal (lienorenal) ligament at the hilum of the spleen (touches spleen)
The 2 ducts of the Pancreas
(1) The main pancreatic (of Wirsung)- drains the tail, body, neck and upper part of the head. Joins the bile duct to form a short tune called Hepatopancreatic ampulla (ampulla of Vater). Opens on major duodenal papilla.
(2) The Accessory Pancreatic Duct (of Santorini)- drains the uncinate process and lower part of the head. Opens at the minor papilla.
What covers the Jejunum and Ileum?
Peritoneum (intraperitoneal) as they are suspended by a mesentery from the posterior abdominal wall
Describe the borders of the mesentery which covers the Jejunum and the Ileum
The mesentery is fan-shaped and has 2 borders:
(1) Attached border (root)- 6 inches long, crosses 3rd part of duodenum, aorta, IVC and under the right ureter and psoas major
(2) Free border- 6 meters long, encloses loops of jejunum and ileum
What provides the vascularization of the Jejunum/Ileum?
SMA
Main differences between Jejunum and Ileum
JEJUNUM:
- More vascular
- Long Vasa Recta
- A few large loops of arterial Arcades
- Large, tall, and closely packed circular folds
- Few Lymphoid nodules
- Thinner fat
ILEUM
- Less vascular
- Short vasa recta
- Many short loops of arterial Arcades
- Low and Sparse circular folds which are absent in distant parts
- Many Lymphoid nodules
- Thicker fat
What does the Large Intestine surround?
It surrounds the small intestine like a “picture frame”
Parts of the Large Intestine, and their associated peritoneal coverings (folds)
- Cecum (retroperitoneal)
- Appendix (mesoappendix)
- Ascending colon (retroperitoneal)
- Transverse colon (transverse mesocolon)
- Descending colon (retroperitoneal)
- Sigmoid colon (Sigmoid mesocolon)
- Rectum (Retroperitoneal)
Divisions of the Colon
Ascending colon, right (hepatic) colic flexure, transverse colon, left (splenic ) colic flexure, descending colon, and sigmoid colon
Components of the large intestine which are fixed are within what type of covering?
Retroperitoneal
The parts of the large intestine which are not fixed
- Appendix
- Transverse colon
- Sigmoid colon
Blood supply of the large intestine
SMA + IMA
Small pouches filled with fat around large intestine.
Appendices epiploicaue
Feature of the Large Intestine
Aka Omental appendices
Absent in Cecum, Appendix and Rectum (CAR) [ COLIC PORTION ONLY]
Taeniae Coli
Feature of the Large Intestine
The outer longitudinal muscle layer is thickened to form 3 bands which are shorter than the other layers. The begin at the base of the appendix and end at the sigmoid colon.