A 1-year-old female is admitted to the hospital with a palpable mass within one of her labia majora. Radiographic examination reveals that a loop of intestine has herniated into the visibly enlarged labium majus. This condition is due to failure of the processus vaginalis to close off. From which of the following tissue layers is the processus derived? ⃣ A. Parietal peritoneum ⃣ B. Extraperitoneal tissue ⃣ C. Transversalis fascia ⃣ D. Dartos fascia ⃣ E. Internal abdominal oblique aponeurosis
1 A. The processus vaginalis (meaning sheathlike process) is composed of parietal peritoneum that precedes the testis as it “migrates” from a position in the upper lumbar wall to a position outside the abdomen. This process usually obliterates, leaving only a distal portion that surrounds most of the testis as the tunica vaginalis. Whereas these features are typical of development in the male, females also have a processus vaginalis that extends into the labia majus, although congenital inguinal hernias are more common in males than females. The other listed structures are not involved in congenital inguinal hernias. GAS 283; GA 140
A 3-year-old boy is admitted to the hospital with signs of acute renal failure. Radiologic studies reveal that the boy has bilateral masses involving both kidneys. Examination of biopsy material confi rms the diagnosis of Wilms tumor. Which of the following gene mutations is the most common in Wilms tumor? ⃣ A. The gene responsible for WT1 ⃣ B. The gene responsible for HGF ⃣ C. The gene responsible for VEGF ⃣ D. The gene responsible for GDNF ⃣ E. The gene responsible for FGF-2
2 A. Wilms tumor is a kidney malignancy that usually occurs in children. It has recently been shown that it can be caused by mutations in the WT1 gene, behaving according to Knudson’s two-hit model for tumor suppressor genes. GAS 355; GA 147
Fusion of the caudal portions of the kidneys during embryonic development is most likely to result in which of the following congenital conditions? ⃣ A. Bicornuate uterus ⃣ B. Cryptorchidism ⃣ C. Horseshoe kidney ⃣ D. Hypospadias ⃣ E. Renal agenesis
3 C. During development, the kidneys typically “ascend” from a position in the pelvis to a position high on the posterior abdominal wall. Although the kidneys are bilateral structures, occasionally the inferior poles of the two kidneys fuse. When this happens, the “ascent” of the fused kidneys is arrested by the fi rst midline structure they encounter, the inferior mesenteric artery. The incidence of horseshoe kidney is about 0.25% of the population. GAS 355; GA 147
Which of the following congenital malformations will most predictably result in oligohydramnios? ⃣ A. Anencephaly ⃣ B. Pyloric stenosis ⃣ C. Renal agenesis ⃣ D. Tracheoesophageal fi stula ⃣ E. Urethral atresia
C. In normal kidney development the kidneys function during the fetal period with the resulting urine contributing to the fl uid in the amniotic cavity. When the kidneys fail to develop (renal agenesis), this contribution to the fl uid is missing and decreased amniotic fl uid (oligohydramnios) results. GAS 355; GA 147
Failure to urinate during embryonic or fetal life usually causes respiratory diffi culties postnatally. Which of the following relationships best describes this situation? ⃣ A. Oligohydramnios linked with hypoplastic lungs ⃣ B. Polycystic kidneys linked to tracheoesophageal fi stula ⃣ C. Polyhydramnios D. ⃣ Renal agenesis linked to insuffi cient surfactant ⃣ E. Urethral obstruction linked to ectopic viscera
A. There is some evidence that oligohydramnios is linked to hypoplastic lungs. This is apparently not a genetic link but rather related to the importance of adequate amniotic fl uid in normal lung development. GAS 163, 355; GA 76, 147
A 4-year-old male child is admitted to the hospital with severe vomiting. Radiographic examination and history taking reveals that the boy suffers from an annular pancreas. Which of the following structures is most typically obstructed by this condition? ⃣ A. Pylorus of the stomach ⃣ B. First part of the duodenum ⃣ C. Second part of the duodenum ⃣ D. Third part of the duodenum ⃣ E. Jejunum
6 C. In normal pancreatic development a bifi d ventral pancreatic bud rotates around the dorsal side of the gut tube and fuses with the dorsal pancreatic bud. Rarely, a portion of the ventral bud rotates around the ventral side of the gut tube, resulting in an annular pancreas. The portion of the gut tube is the same where the main pancreatic duct enters the second part of the duodenum (along with the common bile duct). The incidence of annular pancreas is about 1 in 7000. GAS 322; GA 167
clinic. Diagnosis reveals that the intermediate portion of the processus vaginalis is not obliterated. Which of the following conditions will most likely result from this? ⃣ A. Hypospadias ⃣ B. Sterility ⃣ C. Congenital hydrocele ⃣ D. Ectopic testis ⃣ E. Epispadias
C. The distal portion of the processus vaginalis contributes to the tunica vaginalis that is related to the testis. If an intermediate portion of the processus vaginalis persists, it often fi lls with fl uid, creating a hydrocele. If the entire processus vaginalis persists, the patient is likely to develop a congenital inguinal hernia. GAS 260; GA 225
Testicles are absent from the scrotum of a 1-yearold male admitted to the pediatric clinic. The pediatrician examined the infant and palpated the testes in the inguinal canal. Which of the following terms is used to describe this condition? ⃣ A. Pseudohermaphroditism ⃣ B. True hermaphroditism ⃣ C. Cryptorchism ⃣ D. Congenital adrenal hyperplasia ⃣ E. Chordee
C. Cryptorchism, often called an undescended testis, is the result of incomplete migration of the gonad from the abdomen to a location in the scrotum where it is exposed to temperatures slightly lower than core body temperature. This is important for spermatogenesis and testicular function. A testis that cannot be surgically relocated into the scrotum is usu- ally removed because it would otherwise be prone to develop testicular cancer.
A 28-year-old woman who is 8 months pregnant goes to the outpatient clinic for her prenatal checkup. Ultrasound examination of the fetus reveals gastroschisis, with herniation of the small bowel into the amniotic cavity. Failure of proper formation of which of the following structure(s) has resulted in this condition? ⃣ A. Head fold ⃣ B. Tail fold ⃣ C. Neural folds ⃣ D. Lateral folds ⃣ E. Amnion
D. The lateral folds are key structures in forming the muscular portion of the anterior abdominal wall. Failure of the lateral folds can cause a minor defect, such as an umbilical hernia, or a major defect, such as gastroschisis. GAS 256, 299; GA 154
Rotation of the stomach during development results in movement of the left vagus nerve from its original position. Through approximately how many degrees of rotation does the nerve move, and what is its fi nal position? ⃣ A. 90 ° to become the anterior vagal trunk ⃣ B. 90 ° to become the posterior vagal trunk ⃣ C. 270 ° to become the anterior vagal trunk ⃣ D. 270 ° to become the posterior vagal trunk ⃣ E. 180 ° to become the right vagal trunk
10 A. Rotation of the gut tube is a major event in the development of the gastrointestinal system. Parts of the tube rotate 270 ° , but the proximal foregut, specifi cally that portion that forms the esophagus, rotates only 90 ° . Looking from below (the standard CT or MRI view), this rotation is counterclockwise. This brings the left vagus nerve onto the anterior surface of the esophagus as it passes through the thorax. GAS 256, 345; GA 190
A newborn baby was diagnosed with eventration of the diaphragm, wherein one half of the diaphragm ascends into the thorax during inspiration, but the other half contracts normally. What is the most likely cause of this condition? ⃣ A. Absence of a pleuropericardial fold ⃣ B. Absence of musculature in one half of the diaphragm ⃣ C. Failure of migration of the diaphragm ⃣ D. Failure of development of the septum transversum ⃣ E. Absence of a pleuroperitoneal fold
11 B. The diaphragm develops from several components. Initially, the septum transversum (which will become the central tendon) forms in the cervical region, gaining innervation from C3, C4, and C5. Later, myoblasts migrate in from the body wall to form the muscular part of the diaphragm, often considered to be two bilateral hemidiaphragms. These muscles are innervated by the phrenic nerves. Eventration of the diaphragm occurs when one muscular hemidiaphragm fails to develop. With positive pressure in the abdominal cavity, and low or negative pressure in the thoracic cavity, abdominal organs are pushed into the thorax. The pleuroperitoneal folds contribute to a portion of the diaphragm posteriorly. GAS 353; GA 67
A 2-day-old newborn male is cyanotic after attempts to swallow milk result in collection of the milk in his mouth. After 2 days he develops pneumonia. A tracheoesophageal fi stula is suspected. Which of the following structures has failed to develop properly? ⃣ A. Esophagus ⃣ B. Trachea ⃣ C. Tongue ⃣ D. Tracheoesophageal septum ⃣ E. Pharynx
2 D. The tracheoesophageal septum is the downgrowth that separates the ventral wall of the foregut (esophagus) from the laryngotracheal tube. The presence of a fi stula would result in passage of fl uid from the esophagus into the trachea and could cause pneumonia. If the esophagus did not develop correctly, as in esophageal atresia, it would end as a blind tube. This kind of defect, although associated with tracheoesophageal fi stula, is not the result of an opening into the trachea, and pneumonia would not result. Abnormal tracheal development can be associated with tracheoesophageal fi stula, therefore, but it is not the direct cause of it. Abnormal tongue development does not result in a tracheoesophageal fi stula. Abnormal development of the pharynx is not associated with a tracheoesophageal fi stula. GAS 168; GA 87
A 3-day-old male newborn has diffi culties in breathing. A CT scan of his chest and abdomen reveals the absence of the central tendon of the diaphragm. Which of the following structures failed to develop properly? ⃣ A. Pleuroperitoneal folds ⃣ B. Pleuropericardial folds ⃣ C. Septum transversum ⃣ D. Cervical myotomes ⃣ E. Dorsal mesentery of the esophagus
13 C. The septum transversum forms the central tendon of the diaphragm. The pleuroperitoneal folds form the posterolateral part of the diaphragm. The pleuropericardial folds separate the pericardial cavity from the pleural cavity and form the fi brous pericardium. The cervical myotomes form the musculature of the diaphragm. The dorsal part of the dorsal mesentery of the esophagus forms the crura of the diaphragm. GAS 156; GA 67
A 2-day-old female infant with fever is examined by the pediatric team. Imaging reveals malrotation of the small intestine without fi xation of the mesenteries. The vessels around the duodenojejunal junction are obstructed and the intestine is at risk of becoming gangrenous. Which of the following has occurred to cause the obstruction? ⃣ A. Diaphragmatic atresia ⃣ B. Subhepatic cecum ⃣ C. Midgut volvulus ⃣ D. Duplication of the intestine ⃣ E. Congenital megacolon
14 C. Midgut volvulus is a possible complication of malrotation of the midgut loop without fi xed mesentery. The small intestines twist around the vasculature that is providing support for them. This can result in ischemic necrosis of the intestine. Diaphragmatic atresia is not a cause of volvulus. Subhepatic cecum is due to failure of the descent of the cecal bud and results in the absence of an ascending colon. Duplication of the intestine would not cause volvulus because there would still be a fi xed mesentery and no free movement of the intestines. Congenital megacolon is due to faulty migration of neural crest cells into the wall of the colon, which causes a lack of parasympathetic postganglionic neurons. GAS 299; GA 154
15 A 5-day-old male infant is diagnosed with Hirschsprung disease. CT scan examination reveals an abnormally dilated colon. Which of the following is the most likely embryologic mechanism responsible for Hirschsprung disease? ⃣ A. Failure of neural crest cells to migrate into the walls of the colon ⃣ B. Incomplete separation of the cloaca ⃣ C. Failure of recanalization of the colon ⃣ D. Defective rotation of the hindgut ⃣ E. Oligohydramnios
15 A. Congenital megacolon (Hirschsprung disease) results from the failure of neural crest cells to migrate into the walls of the colon. Incomplete separation of the cloaca would result in anal agenesis either with or without the presence of a fi stula. The failure of recanalization of the colon results in rectal atresia, wherein both the anal canal and rectum exist but are not connected due to incomplete canalization or no recanalization. Defective rotation of the hindgut can cause volvulus or twisting of its contents. Oligohydramnios is a defi ciency of amniotic fl uid, which can cause pulmonary hypoplasia but would not cause Hirschsprung disease. GAS 311; GA 192
A 1-day-old infant has a mass protruding through her umbilicus. Physical examination reveals an umbilical hernia. A CT scan reveals that part of another organ is attached to the inner surface of the hernia. What portion of the gastrointestinal tract is most likely to be attached to the inner surface of the umbilical hernia? ⃣ A. Anal canal ⃣ B. Appendix ⃣ C. Cecum ⃣ D. Ileum ⃣ E. Stomach
D. The ileum is the best answer choice here because it is the most common site of Meckel diverticulum. This outpouching is a persistence of the vitelline duct and it can be attached to the umbilicus. The other answer choices are not correlated with the vitelline duct and therefore will not result in the condition discussed here. GAS 291; GA 155
A 38-year-old pregnant woman is admitted to the emergency department with severe vaginal bleeding. Ultrasound examination confi rms the initial diagnosis of ectopic pregnancy. Which of the following is the most common site of an ectopic pregnancy? ⃣ A. Uterine tubes ⃣ B. Cervix ⃣ C. Mesentery of the abdominal wall ⃣ D. Lower part of uterine body overlapping the internal cervical os ⃣ E. Fundus of the uterus
A. The most common site of ectopic pregnancy is in the uterine tubes. Implantation in the internal os of the cervix can result in placenta previa, but the internal os of the cervix is not the most common site. The other choices listed are not the most common sites of ectopic pregnancy. The fundus of the uterus is the normal site of implantation.
A 23-year-old woman is admitted with severe abdominal pain, nausea, and vomiting. History taking shows that the pain is acute and has been constant for 4 days. The pain began in the epigastric region and radiated bilaterally around the chest to just below the scapulae. Currently the pain is localized in the right hypochondrium. A CT scan examination reveals calcifi ed stones in the gallbladder. Which of the following nerves is carrying the afferent fi bers of the referred pain? ⃣ A. Greater thoracic splanchnic nerves ⃣ B. Dorsal primary rami of intercostal nerves ⃣ C. Phrenic nerves ⃣ D. Vagus nerves ⃣ E. Pelvic splanchnic nerves
A. The greater splanchnic nerve carries general visceral afferent fi bers from abdominal organs and can be involved in the occurrence of referred pain. The dorsal primary rami of intercostal nerves carry general somatic afferent fi bers. Pain from these fi bers would result in sharp, localized pain not dull and diffuse as occurs in referred pain. Although the phrenic nerve carries visceral afferent fi bers, it does not innervate the gallbladder. The vagus nerve carries visceral afferent fi bers that are important for visceral refl exes, but they do not transmit pain. The pelvic splanchnic nerves are parasympathetic nerves from S2 to S4 and contain visceral afferent fi bers that transmit pain from the pelvis but not from the gallbladder.
A 32-year-old male is admitted to the emergency department with groin pain. Examination reveals that the patient has an indirect inguinal hernia. Which of the following nerves is compressed by the herniating structure in the inguinal canal to give the patient pain? ⃣ A. Iliohypogastric ⃣ B. Lateral femoral cutaneous ⃣ C. Ilioinguinal ⃣ D. Subcostal ⃣ E. Pudendal
C. An indirect inguinal hernia occurs when a loop of bowel enters the spermatic cord through the deep inguinal ring (lateral to the inferior epigastric vessels). The ilioinguinal nerve runs with the spermatic cord to innervate the anterior portion of the scrotum and proximal parts of the genitals and could readily be compressed during an indirect inguinal hernia. The other nerves listed are not likely to be compressed by the hernia. The iliohypogastric nerve innervates the skin of the suprapubic region. The lateral femoral cutaneous nerve innervates the skin over the lateral thigh. The subcostal nerve innervates the band of skin superior to the iliac crest and inferior to the umbilicus. The pudendal nerve innervates the musculature and skin of the perineum. GAS 290; GA 140
A 54-year-old male is admitted to the emergency department with severe upper abdominal pain. Gastroscopy reveals a tumor in the antrum of the stomach. A CT scan is ordered to evaluate lymphatic drainage of the stomach. Which of the following lymph nodes is most likely to be involved in a malignancy of the stomach? ⃣ A. Celiac ⃣ B. Superior mesenteric ⃣ C. Inferior mesenteric ⃣ D. Lumbar ⃣ E. Hepatic
A. The celiac lymph nodes receive lymph drainage directly from the stomach before they drain into the cisterna chyli. The superior and inferior mesenteric lymph nodes receive drainage below the stomach and not from the stomach itself. The lumbar lymph nodes receive drainage from structures inferior to the stomach and not the stomach directly. Hepatic lymph nodes are associated with liver drainage and not drainage from the stomach.
During a scheduled laparoscopic cholecystectomy in a 47-year-old female patient, the resident accidentally clamped the hepatoduodenal ligament instead of the cystic artery. Which of the following vessels would most likely be occluded in this iatrogenic injury? ⃣ A. Superior mesenteric artery ⃣ B. Proper hepatic artery ⃣ C. Splenic artery ⃣ D. Common hepatic artery ⃣ E. Inferior vena cava
B. The proper hepatic artery is the only artery typically within the hepatoduodenal ligament and therefore would be occluded. This artery lies within the right anterior free margin of the omental (or epiploic) foramen (of Winslow). The superior mesenteric artery branches from the abdominal aorta inferior to the hepatoduodenal ligament. The splenic artery runs behind the stomach and is not located in the hepatoduodenal ligament. The common hepatic artery gives origin to the proper hepatic artery but does not run within the hepatoduodenal ligament. The inferior vena cava is located at the posterior margin of the omental foramen and therefore would not be clamped.
A 45-year-old male was admitted to the hospital with groin pain and a palpable mass just superior to the inguinal ligament. The patient was diagnosed with an inguinal hernia and a surgical repair was performed. During the operation the surgeon found a loop of intestine passing through the deep inguinal ring. Which of the following types of hernia was this? ⃣ A. Direct inguinal ⃣ B. Umbilical ⃣ C. Femoral ⃣ D. Lumbar ⃣ E. Indirect inguinal
E. Indirect hernias commonly result from herniation of the intestines through the deep inguinal ring. Direct hernias penetrate the anterior abdominal wall medial to the inferior epigastric vessels through the inguinal triangle (of Hesselbach) and do not penetrate the deep inguinal ring. Umbilical hernias exit through the umbilicus, not the deep inguinal ring. Femoral hernias exit through the femoral ring inferior to the inguinal ligament. Lumbar hernias can penetrate through superior (Grynfeltt) or inferior (Petit) lumbar triangles.
A 55-year-old man was admitted to the hospital with severe abdominal pain. Gastroscopy and CT scan examinations revealed a perforating ulcer in the posterior wall of the stomach. Where would peritonitis most likely develop initially? ⃣ A. Right subhepatic space ⃣ B. Hepatorenal space (of Morison) ⃣ C. Omental bursa (lesser sac) ⃣ D. Right subphrenic space ⃣ E. Greater sac
C. The omental bursa is located directly posterior to the stomach and therefore would be the most likely space to develop peritonitis initially. The right subhepatic space (also called the hepatorenal space, or pouch of Morison) is the area posterior to the liver and anterior to the right kidney. This space can potentially accumulate fl uid and may participate in peritonitis but primarily when the patient is in the supine position. The right subphrenic space lies just inferior to the diaphragm on the right side and is not likely to accumulate fl uid from a perforated stomach ulcer. Peritonitis could develop in this area only when the patient is in the supine position. Fluid from a perforated ulcer on the posterior aspect of the stomach is not likely to enter the greater sac.
A 58-year-old male alcoholic is admitted to the hospital after vomiting dark red blood (hematemesis). Endoscopy reveals ruptured esophageal varices, resulting from portal hypertension. Which of the following venous tributaries to the portal system anastomoses with caval veins to cause the varices? ⃣ A. Splenic ⃣ B. Left gastroomental ⃣ C. Left gastric ⃣ D. Left hepatic ⃣ E. Right gastric
24 C. The left gastric vein carries blood from the stomach to the portal vein. At the esophageal-gastric junction the left gastric vein (portal system) anastomoses with esophageal veins (caval system). High blood pressure in the portal system causes high pressure in this anastomosis, causing the ruptured esophageal varices. The splenic vein and its tributaries carry blood away from the spleen and do not form a caval-portal anastomosis. The left gastroomental vein accompanies the left gastroomental artery and joins the splenic vein with no direct anastomosis with caval veins. The left hepatic vein is a caval vein and empties into the inferior vena cava. The right gastric vein drains the lesser curvature of the stomach and is part of the portal system but does not have any caval anastomosis.
A 45-year-old male entered the emergency department with a complaint of severe abdominal pain. During physical examination it is observed that his cremasteric refl ex is absent. Which of the following nerves is responsible for the efferent limb of the cremasteric refl ex? ⃣ A. Ilioinguinal ⃣ B. Iliohypogastric ⃣ C. Genitofemoral ⃣ D. Pudendal ⃣ E. Ventral ramus of T12
C. The genitofemoral nerve originates from the ventral rami of L1 and L2. The femoral part supplies skin to the femoral triangle area, whereas the “genito” part in males travels with the spermatic cord and supplies the cremaster muscle and scrotal skin. The ilioinguinal nerve arises from L1 and supplies the skin over the root of the penis and upper part of the scrotum in the male. The iliohypogastric nerve arises from L1 (and possibly fi bers from T12) and supplies skin innervation over the hypogastric region and anterolateral gluteal region. The pudendal nerve provides innervation to the external genitalia for both sexes but does not innervate the cremaster muscle in males. The ventral ramus of T12 is also associated with the lower portion of the anterior abdominal wall and the iliohypogastric nerve; it does not contribute to the cremasteric refl ex.
The decision is made by emergency department surgeons to perform an exploratory laparotomy on a 32-year-old female with severe abdominal pain. Where would the incision most likely be made to separate the left and right rectus sheaths? ⃣ A. Midaxillary line ⃣ B. Arcuate line ⃣ C. Semilunar line ⃣ D. Tendinous intersection ⃣ E. Linea alba
E. The linea alba is formed by the intersection of aponeurotic tissues between the right and left rectus abdominal muscles. It contains the aponeuroses of the abdominal muscles and is located at the midline of the body. The midaxillary line is oriented vertically in a straight line inferior to the shoulder joint and axilla. The arcuate line (of Douglas) is a curved horizontal line that represents the lower edge of the posterior tendinous portion of the rectus abdominis sheath. An incision at this line will not separate the rectus abdominis sheaths. The semilunar line is represented by an imaginary vertical line below the nipples and usually parallels the lateral edge of the rectus sheath. The tendinous intersections of the rectus abdominis muscles divide the muscle into sections and are usually not well defi ned. An incision along these intersections would not divide the two rectus sheaths.
After a “tummy-tuck” (abdominoplasty) procedure is performed on a 45-year-old man, which of the following layers of the abdominal wall will hold the sutures? ⃣ A. Scarpa’s fascia (membranous layer) ⃣ B. Camper’s fascia (fatty layer) ⃣ C. Transversalis fascia ⃣ D. Extraperitoneal tissue ⃣ E. External abdominal oblique fascia
A. Scarpa’s fascia is the thick, membranous layer deep to the Camper’s adipose fascia in the anterior abdominal wall (subcutaneous). Because of the relatively thick, tough nature of connective tissue that makes up Scarpa’s fascia, this layer is typically the site to maintain sutures. Camper’s fascia is a fatty layer (subcutaneous) and tends not to hold sutures as well, due to the increased cellular content versus the connective tissue found in the Scarpa layer. Transversalis fascia is located deep to the abdominal musculature and associated aponeurosis. Extraperitoneal fascia is the deepest layer, adjacent to the parietal peritoneum of the anterior abdominal wall. The anterior wall of the rectus sheath is the layer just deep to Scarpa’s fascia and superfi cial to the rectus abdominis muscle anteriorly. The latter three layers are not considered to be superfi cial fascia.
A 49-year-old man presents with acute abdominal pain and jaundice. Radiographic studies reveal a tumor in the head of the pancreas. Which of the following structures is most likely being obstructed? ⃣ A. Common bile duct ⃣ B. Common hepatic duct ⃣ C. Cystic duct ⃣ D. Accessory pancreatic duct ⃣ E. Proper hepatic artery
A. The common bile duct is located at the head of the pancreas and receives contents from the cystic duct and hepatic duct. An obstruction at this site causes a backup of bile back through the common bile duct and hepatic duct, with resulting pain and jaundice. The common hepatic duct is located more superior to the head of the pancreas and leads into the cystic duct. The cystic duct allows bile to enter the gallbladder from the common bile duct (draining the liver) and releases bile to the common bile duct. The accessory pancreatic duct is not affected by an obstruction of the common bile duct due to a lack of any connections between the two ducts. The proper hepatic artery will not be obstructed, for it carries blood from the liver to the inferior vena cava.
A 44-year-old man is admitted to the emergency department with excessive vomiting and dehydration. Radiographic images demonstrate that part of the bowel is being compressed between the abdominal aorta and the superior mesenteric artery. Which of the following intestinal structures is most likely being compressed? ⃣ A. Second part of duodenum ⃣ B. Transverse colon ⃣ C. Third part of duodenum ⃣ D. First part of duodenum ⃣ E. Jejunum
C. The third part of the duodenum takes a path situated anterior to the abdominal aorta and inferior to the superior mesenteric artery (a major ventral branch of the abdominal aorta). Because the third part of the duodenum lies in the angle between (“sandwiched”) these two structures, constrictions of this portion of the duodenum can occur readily. The second part of the duodenum lies parallel with, and to the right of, the abdominal aorta and is not normally in close proximity to the superior mesenteric artery. The transverse colon takes a horizontal path through the anterior abdominal cavity but travels superior or anterior to the superior mesenteric artery. The fi rst part of the duodenum continues from the pylorus, fl exing to lead to the second part of the duodenum; thus, it is not located near the superior mesenteric artery or abdominal aorta. The jejunum is an extension of the small intestine after the duodenum and is further removed from the superior mesenteric artery.
During the surgical repair of a perforated duodenal ulcer in a 47-year-old male patient, the gastroduodenal artery is ligated. A branch of which of the following arteries will continue to supply blood to the pancreas in this patient? ⃣ A. Inferior mesenteric ⃣ B. Left gastric ⃣ C. Right gastric ⃣ D. Proper hepatic ⃣ E. Superior mesenteric
E. The superior mesenteric artery will supply the pancreas if the gastroduodenal artery is ligated. It arises immediately inferior to the celiac trunk from the thoracic aorta. Its fi rst branches are the anterior and posterior inferior pancreaticoduodenal arteries, which aid the superior pancreaticoduodenal arteries (which take origin from the gastroduodenal branch of the celiac trunk) in supplying the pancreas with oxygenated blood. The inferior mesenteric artery is the most inferior of the three main arterial branches supplying the gastrointestinal tract. It supplies the hindgut from the left colic fl exure to the rectum. The left gastric artery is the smallest branch of the celiac trunk and supplies the cardioesophageal junction, the inferior esophagus, and the lesser curvature of the stomach. Its anastomosis with branches from the thoracic aorta forms one of the four main portal-caval anastomoses. The right gastric artery arises from the common hepatic artery, which is a branch from the celiac trunk. It supplies the lesser curvature of the stomach and anastomoses with the left gastric artery. The proper hepatic artery arises from the common hepatic artery and ascends to supply the liver and gallbladder. It is one of three structures forming the portal triad and is found in the free edge of the hepatoduodenal ligament. GAS 333, 336; GA 169