A 35-year-old man comes to the emergency department due to persistent abdominal pain. Yesterday, during a soccer game, he suffered a full-speed collision with another player. He had diffuse abdominal pain at the time but did not seek care until this morning, when the pain seemed to worsen. As part of the patient's evaluation, a CT scan of the abdomen is obtained and shown in the image below. It is determined that his injury involves an organ that is supplied mainly by an artery of the foregut even though the organ itself is not a foregut derivative. Which of the following organs is most likely to be injured in this patient?

Question

A 35-year-old man comes to the emergency department due to persistent abdominal pain.  Yesterday, during a soccer game, he suffered a full-speed collision with another player.  He had diffuse abdominal pain at the time but did not seek care until this morning, when the pain seemed to worsen.  As part of the patient's evaluation, a CT scan of the abdomen is obtained and shown in the image below.  It is determined that his injury involves an organ that is supplied mainly by an artery of the foregut even though the organ itself is not a foregut derivative.  Which of the following organs is most likely to be injured in this patient?

Quizplus · Accepted Answer

The most common intra-abdominal organ injured during blunt trauma is the spleen. CT scans and MRI are conventionally presented so that the patient's left is on the reader's right (imagine that the patient is supine with the feet directed toward the viewer). This is a relatively caudal (lower) abdominal image that includes the kidneys; therefore, only the tail of the spleen is visible. The spleen is an intraperitoneal organ derived from the mesoderm of the dorsal mesentery. However, the spleen is unique in that its blood supply derives from a foregut derivative (the splenic artery off of the celiac trunk). Venous return from the spleen courses through the splenic vein to return to the portal circulation rather than the systemic circulation. (Choice A) The liver is an endoderm-derived structure of the foregut and receives its arterial blood from the proper hepatic artery (via the celiac trunk). The liver also receives venous blood from the gut via the portal vein. (Choice B) Like the spleen, the kidneys are derived from the mesoderm. However, the kidneys are retroperitoneal and supplied by the renal arteries (from the abdominal aorta) and drained by the renal veins (to the inferior vena cava). (Choice C) The first two-thirds of the transverse colon is derived from the midgut and supplied by the superior mesenteric artery. The last one-third of the transverse colon arises from the hindgut and is supplied by branches of the inferior mesenteric artery. These 2 vessels anastomose via the marginal artery. (Choice D) The pancreas is an endoderm-derived structure of the foregut that receives blood primarily from the superior and inferior pancreaticoduodenal arteries. Educational objective: The spleen is of mesodermal origin (the dorsal mesentery). Although it is supplied by the splenic artery (a branch of the major foregut vessel, the celiac trunk), it is not a foregut derivative. __________ References: Embryonic origins of spleen asymmetry. (http://www.ncbi.nlm.nih.gov/pubmed/10654610)

A 35-Year-Old Man Comes to the Emergency Department Due to Persistent