Lesson11, The gastrointestinal tract, MMed Anatomy, Imaging

Lesson11, The gastrointestinal tract, MMed Anatomy, Imaging

Clinical

Duodenal ulcers. Most inflammatory erosions of the duodenal wall, duodenal (peptic) ulcers, are in the posterior wall of the superior (1^st ) part of the duodenum within 3 cm of the pylorus. (Grants p134).

Large Intestine: the features of the large intestine are the taeniae coli; haustra; and omental appendices.  

The descending colon is the narrowest part of the large intestine and retroperitoneal.

Barium enema and colonoscopy of colon: (grant’s p138)

v  Single contrast study: A barium enema has filled the colon

v  Double contrast Study: Barium can be seen coating the walls of the colon, which is distended with air (the double contrast per Dr F Joseph, UP), providing a vivid view of the mucosal relief and haustra.

v  Diverticulosis:

Ø  Fiberoptic Flexible Colonoscopy: The interior of the colon can be observed with an elongated endoscope, usually fiberoptic flexible colonoscope. The endoscope is a tube that inserts into the colon through the anus and rectum.

Ø  Diverticulosis of the colon can be photographed through a colonoscope. (does this mean that there is diverticulosis elsewhere in the GIT?)

Ø  Diverticulosis is a disorder in which multiple false diverticula (external evaginations or out-pocketing of the mucosa of the colon) develop along the intestine. It primarily affects middle aged or elderly people. Diverticulosis is commonly (60%) found in the sigmoid colon. Diverticula are subject to infection and rapture, leading to diverticulitis, and they can distort and erode the nutrient arteries, leading to hemorrhage.

Ilead diverticulum of Meckle. Ilial diverticulum is a congenital anomaly that occurs in 1 to 2 % of persons. It is a pouch like remnant (3 to 6 cm long) of the proximal part of the yolk sac, typically within 50 cm of the ileocecal junction. It sometimes becomes inflamed and produces pain that may mimic that produced by appendicitis. Grant p139.

Appendicitis: Acute inflammation of the appendix is a common cause of acute abdomen (severe abdominal pain arising suddenly). The pain of appendicitis usually commences as a vague pain in the periumbilical region because of the afferent pain fibres enter the spinal cord at the T10 level. Later, severe pain in the right lower quadrant results from irritation of the parietal peritoneum lining the posterior abdominal wall.

Superior Mesenteric Artery

Ø  The superior mesenteric artery ends by anastomosing with one of its own branches, the ilial branch of the ileocolic artery.

Ø  Vasa recta from the Arterial arcades of the Jejunum are longer than the short vasa recta of Arterial Arcades the Ileum.

Ø  The left renal vein, duodenum and uncinate process pass between the superior mesenteric artery and the aorta. Compressed.

Ø  Ileus of the paralytic type:

§  Occlusion of the vasa recta: by emboli results in ischemia of the part of the intestine concerned. If the ischemia is severe, necrosis of the involved segment results and ileus (obstruction of the intestine) of the paralytic type occurs. Ileus is accompanied by severe colicky pain, along with abdominal distension, vomiting, and often fever and dehydration. If the condition is diagnosed early by superior mesenteric angiogram, the obstructed part of the vessel may be cleared surgically.

Inferior Mesenteric Artery. Grant 142

v  The inferior mesenteric artery arises about 4 cm superior to the aortic bifurcation and crosses the left common iliac vessels to become the superior rectal artery

v  Branches seen on inferior mesenteric angiogram

Ø  Left colic artery

§  Ascending and Descending branches

Ø  Several Sigmoidal Arteries (Four)

§   (The inferior two sigmoidal arteries branch from the superior mesenteric artery)

Ø  Superior Rectal Artery

§  Supplies the rectum,

Ø  the superior rectal anastomoses is formed by the branches of the middle and inferior rectal arteries (from internal iliac artery)

v  Critical point: the point at which the last artery to the colon branches from the superior rectal artery is known as the critical point; this branch has no anastomotic connections with the superior rectal artery.