Abdomen and Pelvis III Flashcards
Surgical occlusion of which of these structures, will result in the greatest reduction in hepatic blood flow?
A. Portal vein B. Common hepatic artery C. Right hepatic artery D. Coeliac axis E. Left hepatic artery
Portal vein
The portal vein transports 70% of the blood supply to the liver, while the hepatic artery provides 30%. The portal vein contains the products of digestion. The arterial and venous blood is dispersed by sinusoids to the central veins of the liver lobules; these drain into the hepatic veins and then into the IVC. The caudate lobe drains directly into the IVC rather than into other hepatic veins.
A 23 year old man presents with appendicitis. A decision is made to perform an appendicectomy. The operation commences with a 5cm incision centered on McBurneys point. Which of the following structures will be encountered first during the dissection?
A. External oblique aponeurosis B. Internal oblique muscle C. Transversalis fascia D. Rectus sheath E. Peritoneum
The external oblique will be encountered first in this location. The rectus sheath lies more medially.
The external oblique muscle is the most superficial of the abdominal wall muscles. It originates from the 5th to 12th ribs and passes inferomedially to insert into the linea alba, pubic tubercle and anterior half of the iliac crest. It is innervated by the thoracoabdominal nerves (T7-T11) and sub costal nerves.
A 45 year old man is undergoing a low anterior resection for a carcinoma of the rectum. Which of the following fascial structures will need to be divided to mobilise the mesorectum from the sacrum and coccyx?
A. Denonvilliers fascia B. Colles fascia C. Sibsons fascia D. Waldeyers fascia E. None of the above
Waldeyers fascia
Fascial layers surrounding the rectum:
Anteriorly lies the fascia of Denonvilliers
Posteriorly lies Waldeyers fascia
Waldeyers fascia separates the mesorectum from the sacrum and will need to be divided.
A 73 year old lady is admitted with acute mesenteric ischaemia. A CT angiogram is performed and a stenotic lesion is noted at the origin of the superior mesenteric artery. At which of the following levels does this branch from the aorta?
A. L1 B. L2 C. L3 D. L4 E. L5
SMA
The SMA leaves the aorta at L1. It passes under the neck of the pancreas prior to giving its first branch the inferior pancreatico-duodenal artery.
Superior mesenteric artery
Branches off aorta at L1
Supplies small bowel from duodenum (distal to ampulla of vater) through to mid transverse colon
Takes more oblique angle from aorta and thus more likely to recieve emboli than coeliac axis
Relations of superior mesenteric artery Superiorly Neck of pancreas Postero-inferiorly Third part of duodenum Uncinate process Posteriorly Left renal vein Right Superior mesenteric vein
Branches of the superior mesenteric artery Inferior pancreatico-duodenal artery Jejunal and ileal arcades Ileo-colic artery Right colic artery Middle colic artery
A 72 year old man is undergoing an open abdominal aortic aneurysm repair. The aneurysm is located in a juxtarenal location and surgical access to the neck of aneurysm is difficult. Which of the following structures may be divided to improve access?
A. Cisterna chyli B. Transverse colon C. Left renal vein D. Superior mesenteric artery E. Coeliac axis
left renal vein
The left renal vein will be stretched over the neck of the anuerysm in this location and is not infrequently divided. This adds to the nephrotoxic insult of juxtarenal aortic surgery as a supra renal clamp is also often applied. Deliberate division of the Cisterna Chyli will not improve access and will result in a chyle leak. Division of the transverse colon will not help at all and would result in a high risk of graft infection. Division of the SMA is pointless for a juxtarenal procedure.
A 53 year old man presents with an inguinal hernia. Which of the following surface landmarks may be used to identify the location of the deep inguinal ring?
A. Mid point of the inguinal ligament B. The mid inguinal point C. The pubic tubercle D. The medial edge of external oblique E. 2cm supero medially to the femoral artery
Mid point of the inguinal ligament
Surface marking of deep inguinal ring = midpoint of inguinal ligament
The surface markings of the deep inguinal ring are a commonly examined topic and should be memorised. The surface marking is the midpoint of the inguinal ligament. The mid inguinal point is the surface marking for the femoral artery. The pubic tubercle marks the site of the superficial inguinal ring.
A patient is found to have an ischaemic left colon. Which artery arising from the aorta at around the level of L3 is most likely to account for this situation?
A. Superior mesenteric artery B. Inferior mesenteric artery C. Superior rectal artery D. Ileocolic artery E. Middle colic artery
Only the IMA is likely to affect the left side of the colon and originate at L3.
An enthusiastic surgical registrar undertakes his first solo splenectomy. The operation is far more difficult than anticipated and the registrar leaves a tube drain to the splenic bed at the end of the procedure. Over the following 24 hours approximately 500ml of clear fluid has entered the drain. Biochemical testing of the fluid is most likely to reveal:
A. Elevated creatinine B. Elevated triglycerides C. Elevated glucagon D. Elevated amylase E. None of the above
Amylase
During splenectomy the tail of the pancreas may be damaged. The pancreatic duct will then drain into the splenic bed, amylase is the most likely biochemical finding. Glucagon is not secreted into the pancreatic duct.
A 56 year old lady is referred to the colorectal clinic with symptoms of pruritus ani. On examination a polypoidal mass is identified inferior to the dentate line. A biopsy confirms squamous cell carcinoma. To which of the following lymph node groups will the lesion potentially metastasise?
A. Internal iliac B. External iliac C. Mesorectal D. Inguinal E. None of the above
Inguinal
Lesions distal to the dentate line drain to the inguinal nodes. Occasionally this will result in the need for a block dissection of the groin.
A 20 year old man is hit with a hammer on the right side of the head. He dies on arrival in the emergency department. Which of these features is most likely to be found at post mortem?
A. Hydrocephalus B. Supra tentorial herniation C. Laceration of the middle meningeal artery D. Sub dural haematoma E. Posterior fossa haematoma
Middle meningeal
This will account for the scenario given where there is a brief delay prior to death. The other options are less acute and a supratentorial herniation would not occur in this setting.
A 72 year old man develops a hydrocele which is being surgically managed. As part of the procedure the surgeons divide the tunica vaginalis. From which of the following is this structure derived?
A. Peritoneum B. External oblique aponeurosis C. Internal oblique aponeurosis D. Transversalis fascia E. Rectus sheath
Peritoneum
The tunica vaginalis is derived from peritoneum, it secretes the fluid that fills the hydrocele cavity.
A 43 year old lady is donating her left kidney to her sister and the surgeons are harvesting the left kidney. Which of the following structures will lie most anteriorly at the hilum of the left kidney?
A. Left renal artery B. Left renal vein C. Left ureter D. Left ovarian vein E. Left ovarian artery
Left renal vein
The renal veins lie most anteriorly, then artery and ureter lies posteriorly.
A 56 year old lady is due to undergo a left hemicolectomy for carcinoma of the splenic flexure. The surgeons decide to perform a high ligation of the inferior mesenteric vein. Into which of the following does this structure usually drain?
A. Portal vein B. Inferior vena cava C. Left renal vein D. Left iliac vein E. Splenic vein
Splenic vein
Beware of ureteric injury in colonic surgery.
The inferior mesenteric vein drains into the splenic vein, this point of union lies close to the duodenum and this surgical maneouvre is a recognised cause of ileus.
A man undergoes a high anterior resection for carcinoma of the upper rectum. Which of the following vessels will require ligation?
A. Superior mesenteric artery B. Inferior mesenteric artery C. Coeliac axis D. Perineal artery E. Middle colic artery
IMA
The IMA is usually divided during anterior resection. Not only is this borne out of oncological necessity but it also permits sufficient colonic mobilisation for anastomosis.
During a radical gastrectomy for carcinoma of the stomach the surgeons remove the omentum. What is the main source of its blood supply?
A. Ileocolic artery B. Superior mesenteric artery C. Gastroepiploic artery D. Middle colic artery E. Inferior mesenteric artery
Gastro-epiploic artery
The vessels supplying the omentum are the omental branches of the right and left gastro-epiploic arteries. The colonic vessels are not responsible for the arterial supply to the omentum. The left gastro-epiploic artery is a branch of the splenic artery and the right gastro-epiploic artery is a terminal branch of the gastroduodenal artery.
