Clinical Anatomy of Bleeding in the GI Tract Flashcards
Name the parts of the colon and their relationship with peritoneum
Caecum - intraperitoneal Ascending colon - retroperitoneal Transverse colon - intraperitoneal Descending colon - retroperitoneal Sigmoid colon - intraperitoneal
Describe the location and clinical relevance of the paracolic gutters
The two paracolic gutters are found on the left and right sides between the two lateral edges of the ascending and descending colon and the abdominal wall
They are clinically relevant as they are potential sites for pus drainage
Describe the distinguishing features of the colon
Omental appendicies - small fatty projections
Teniae coli - three longitudinal bands of thickened smooth muscle that come together at the appendix
Haustra - radiological features formed by contraction of teniae coli
Where is the appendix most often found anatomically?
Behind the caecum
Describe the orifices present on the posteromedial wall of the caecum
Ileocaecal - formed by the ileum invaginating into the caecum
Appendiceal - corresponds to McBurney’s point (1/3 of the way between right ASIS and umbilicus) and is said to be point of maximum tenderness in appendicitis
Describe the location of the sigmoid colon and the effect of sigmoid volvulus
The sigmoid colon lies in the left iliac fossa
It has a long mesentery which gives it a great deal of movement. However the sigmoid colon may twist around itself (sigmoid volvulus) resulting in bowel obstruction and potential necrosis and infarction
Name the branches of the abdominal aorta, where they branch and the structures they supply
Coeliac trunk - branches at T12 to supply foregut organs
Superior mesenteric artery - branches at L1 to supply midgut organs
Renal artery - branches at L1 to supply kidneys/adrenal glands
Gonadal artery - branches at L2 to supply gonads
Inferior mesenteric artery - branches at L3 to supply hindgut organs
Describe the bifurcation of the abdominal aorta
The abdominal aorta bifurcates into common iliacs at L4, which further bifurcate to internal and external iliacs
Name the branches of the superior mesenteric artery and the structures they supply
From superior to inferior:
Inferior pancreaticoduodenal - supplies pancreas
Middle colic - supplies transverse colon
Right colic - supplies ascending colon
Ileocolic branches - gives off appendicular, jejunal and ileal arteries
State the main differences between jejunal and ileal arteries
Jejunal arteries have longer vasa rectae
Jejunal arteries have longer and fewer arcades
Name the branches of the inferior mesenteric artery and the structures they supply
Left colic artery - supplies descending colon
Sigmoid artery - supplies sigmoid colon
Superior rectal artery - supplies rectum and proximal half of anal canal
Explain the marginal artery of Drummond and its clinical benefit
The marginal artery of Drummond is formed by the anastamoses of branches of the SMA and IMA along the length of the large intestine
It means that if there is a blockage of the SMA/IMA ischaemia is avoided by providing an alternative route for blood to travel
Describe the blood supply to the rectum and anal canal
Superior rectal artery supplies rectal and proximal half of anal canal
Internal iliac artery supplies remainder of the GI tract
Name the different veins of the hepatic portal system and their functions
Inferior vena cava - drains blood from hepatic veins into RA
Hepatic portal vein - drains blood from foregut, midgut and hindgut structures to liver
Splenic vein - drains blood from foregut to HPV
Superior mesenteric vein - drains blood from midgut to HPV
Inferior mesenteric vein - drains blood from hindgut to splenic vein
Where are the three clinically important sites of venous anastomoses between the systemic and portal systems? What is the blood flow to these sites like?
Site around umbilicus
Distal end of oesophagus
Rectum/anal canal
There is normally very little blood flow between these veins
