Block 6 Anatomy Abdomen BRS Pretest W Xpl Prt 1

1. A 13-year-old boy was vacationing with his parents in Mexico on spring break. He developed nausea, vomiting 4 days into the trip despite caution about what he ate and drank. He switched to a clear liquid diet. None of the others on the trip were sick. On his flight back to the United States the next day he developed a fever and increased abdominal pain, especially in the paraumbilical region. His parents took him to their pediatrician the next day as he was feeling worse and could barely move. During the physical exam the pediatrician noted tenderness around the umbilicus and rebound tenderness over McBurney's point and was sent for an abdominal CT at a local pediatric hospital. Where is McBurney's point and what is the likely diagnosis?

At the right costal margin at the mid-clavicular line; ruptured gallbladder

On a line drawn between the anterior superior iliac spine and umbilicus on the right; appendicitis

On a line drawn between the anterior superior iliac spine and umbilicus on the left; appendicitis

On a line drawn between the anterior superior iliac spine and the pubic tubercle on the right; kidney stone

On a line drawn between the anterior superior iliac spine and the pubic tubercle on the left; kidney stone

(Moore and Dalley, pp 208–209, 275.) Rebound tenderness over McBurney’s point is the likely diagnosis for an appendicitis. McBurney’s point is generally described at 1.5–2 in. superomedial on a line drawn between the patient’s right (thus left and answer c is wrong) anterior
superior iliac spine and the umbilicus. This is the approximate location of the ileocecal junction near where the appendix would lie deep to the anterior abdominal wall. The history of first umbilical pain and nausea and vomiting is consistent with appendicitis, not kidney stones (answers d and e). The inguinal ligament courses between the anterior superior iliac spine and the pubic tubercle, which is the lateral portion of the pubic crest. While kidney stones are very painful they are not always associated with vomiting, nor does the pain locate to either the umbilical region or McBurney’s point. Gallbladder pain often presents with rebound tenderness at the right costal margin at the mid-clavicular line (answer a).

Explanation

(Moore and Dalley, pp 208–209, 275.) Rebound tenderness over McBurney’s point is the likely diagnosis for an appendicitis. McBurney’s point is generally described at 1.5–2 in. superomedial on a line drawn between the patient’s right (thus left and answer c is wrong) anterior
superior iliac spine and the umbilicus. This is the approximate location of the ileocecal junction near where the appendix would lie deep to the anterior abdominal wall. The history of first umbilical pain and nausea and vomiting is consistent with appendicitis, not kidney stones (answers d and e). The inguinal ligament courses between the anterior superior iliac spine and the pubic tubercle, which is the lateral portion of the pubic crest. While kidney stones are very painful they are not always associated with vomiting, nor does the pain locate to either the umbilical region or McBurney’s point. Gallbladder pain often presents with rebound tenderness at the right costal margin at the mid-clavicular line (answer a).

2. A multiparous mother brings in her second son, an 18-month-old active toddler, because she has noticed blood (sometimes red, one time "currant jelly") in his stools. Although the toddler is trying new foods, she doesn't think the blood is associated with anything in his diet. Your physical exam, including a digital rectal exam, is normal. You order an upper GI barium swallow with small bowel follow through and radiological report describes a 2-inchlong diverticulum, pointing toward the umbilicus, in the ileum, about 2 ft from the ileocecal valve. You explain to the mother that the blood is most likely from which of the following sources?

An appendix that must be removed

A Meckel’s (ileal) diverticulum

Active diverticulitis

Internal hemorrhoids

A duodenal ulcer

(Moore and Dalley, pp 270–271.) Meckel’s (ileal) diverticuli are the most common congenital abnormality of the digestive system. They are a remnant of the herniation and rotation of the midgut and at times the diverticulum remains attached to the umbilicus by a connective tissue stalk, as is mostly likely the case here. The diverticulum generally extends 2 inches from the ileum; about 2 ft from the ileocecal valve and usually manifests itself by bleeding prior to the first 2 years of life. There may be two types of ectopic tissue present in the diverticulum: either acid secreting epithelium (stomach; detected with radioactive technetium injected into the venous blood stream which then accumulates within the diverticulum) or pancreatic epithelium. (The rule of “2” helps remind you of the characteristics of Meckel’s diverticulum.) The appendix (answer a) is a diverticulum off the cecum, not the ileum. Diverticuli (answer c) can cause blood in the stool but would be extremely rare in a toddler. Internal hemorrhoids (answer d) would generally be detected in a rectal exam, especially in a toddler and is not associated with “currant jelly” stools. The blood would more likely be black if a duodenal ulcer (answer e) were present, which would also be very rare in a toddler.

Explanation

(Moore and Dalley, pp 270–271.) Meckel’s (ileal) diverticuli are the most common congenital abnormality of the digestive system. They are a remnant of the herniation and rotation of the midgut and at times the diverticulum remains attached to the umbilicus by a connective tissue stalk, as is mostly likely the case here. The diverticulum generally extends 2 inches from the ileum; about 2 ft from the ileocecal valve and usually manifests itself by bleeding prior to the first 2 years of life. There may be two types of ectopic tissue present in the diverticulum: either acid secreting epithelium (stomach; detected with radioactive technetium injected into the venous blood stream which then accumulates within the diverticulum) or pancreatic epithelium. (The rule of “2” helps remind you of the characteristics of Meckel’s diverticulum.) The appendix (answer a) is a diverticulum off the cecum, not the ileum. Diverticuli (answer c) can cause blood in the stool but would be extremely rare in a toddler. Internal hemorrhoids (answer d) would generally be detected in a rectal exam, especially in a toddler and is not associated with “currant jelly” stools. The blood would more likely be black if a duodenal ulcer (answer e) were present, which would also be very rare in a toddler.

3. Gallbladder pain often presents as epigastric pain that then migrates towards the patient's right side and can even wrap around to the posterior. The referred pain is not the site of the problem. Anatomically where is the gallbladder located?

Between the left and caudate lobes of the liver

Between the right and quadrate lobes of the liver

In the falciform ligament

In the lesser omentum

In the right anterior leaf of the coronary ligament

(Moore and Dalley, pp 290–291, 295.) The gallbladder lies on the inferior surface of the liver between the right and quadrate lobes [thus not (answer a)]. The caudate lobe lies posteriorly between the right and left lobes. The falciform ligament, a portion of the lesser omentum, attaches to the liver at the incisura between the quadrate and left lobes as well as along the fissure for the round ligament. Toward the superior surface of the liver, the falciform ligament (answer c) splits to form the left and right coronary ligaments, which define the bare area of the liver. The coronary ligaments (answer e) come together again to form the gastrohepatic ligament of the lesser omentum (answer d).

Explanation

(Moore and Dalley, pp 290–291, 295.) The gallbladder lies on the inferior surface of the liver between the right and quadrate lobes [thus not (answer a)]. The caudate lobe lies posteriorly between the right and left lobes. The falciform ligament, a portion of the lesser omentum, attaches to the liver at the incisura between the quadrate and left lobes as well as along the fissure for the round ligament. Toward the superior surface of the liver, the falciform ligament (answer c) splits to form the left and right coronary ligaments, which define the bare area of the liver. The coronary ligaments (answer e) come together again to form the gastrohepatic ligament of the lesser omentum (answer d).

4. A full-term male infant displays projectile vomiting 1 h after suckling. There is failure to gain weight during the first 48 hours. The vomitus is not bile-stained and no respiratory difficulty is evident. Examination reveals an abdomen neither tense nor bloated. Which of the following is the most probable explanation?

Congenital hypertrophic pyloric stenosis

Congenital absence of a kidney

Patent ileal diverticulum

Imperforate anus

Tracheoesophageal fistula

(Moore and Dalley, p 256.) Blockage of the foregut in the newborn produces projectile vomiting. Congenital hypertrophic pyloric stenosis, occurring in 0.5–1.0% of males and rarely in females, involves hypertrophy of the circular layer of muscle at the pylorus. This usually does not regress and must be treated surgically. During the 5th and 6th weeks of development, the lumen of the duodenum is occluded by muscle proliferation but normally recanalizes during the eighth week. Failure of recanalization results in duodenal atresia. Because this occurs proximal to the hepatopancreatic ampulla, the vomitus will occasionally be stained with bile. Annular pancreas, rare in itself, seldom completely
blocks the duodenum. Congenital absence of a kidney (answer b) would not present with the symptoms described. Imperforate anus (answer d) results in intestinal distention with bloating. A newborn with a typical tracheoesophageal fistula (answer e) can not feed without aspiration. A newborn with a patent ileal diverticulum (answer c) would present with stool coming out his umbilicus.

Explanation

(Moore and Dalley, p 256.) Blockage of the foregut in the newborn produces projectile vomiting. Congenital hypertrophic pyloric stenosis, occurring in 0.5–1.0% of males and rarely in females, involves hypertrophy of the circular layer of muscle at the pylorus. This usually does not regress and must be treated surgically. During the 5th and 6th weeks of development, the lumen of the duodenum is occluded by muscle proliferation but normally recanalizes during the eighth week. Failure of recanalization results in duodenal atresia. Because this occurs proximal to the hepatopancreatic ampulla, the vomitus will occasionally be stained with bile. Annular pancreas, rare in itself, seldom completely
blocks the duodenum. Congenital absence of a kidney (answer b) would not present with the symptoms described. Imperforate anus (answer d) results in intestinal distention with bloating. A newborn with a typical tracheoesophageal fistula (answer e) can not feed without aspiration. A newborn with a patent ileal diverticulum (answer c) would present with stool coming out his umbilicus.

5. You deliver a newborn baby girl that has an umbilical hernia with part of another organ attached to its inner surface. What portion of the gastrointestinal tract is most likely to be attached to the inner surface of the umbilical hernia?

Anal canal

Appendix

Cecum

Ileum

Stomach

(Moore and Dalley, pp 270, 271.) During the first month of development, the midgut communicates over its entirety with the yolk sac. This connection narrows during the second month to form the vitelline duct (yolk stalk, omphalomesenteric duct) as the midgut closes and usually disappears during the ninth week. Because the vitelline duct joins the ileum, this section of the gastrointestinal tract is the last to close. Failure of closure results in a persistent vitelline fistula, whereas partial obliteration results in an ileal diverticulum (of Meckel). The ileal diverticulum and umbilical hernia would most likely be repaired at the same time. Other regions (answers a, b, c and e) of the gastrointestinal tract are
unlikely to be attached to the anterior abdominal wall.

Explanation

(Moore and Dalley, pp 270, 271.) During the first month of development, the midgut communicates over its entirety with the yolk sac. This connection narrows during the second month to form the vitelline duct (yolk stalk, omphalomesenteric duct) as the midgut closes and usually disappears during the ninth week. Because the vitelline duct joins the ileum, this section of the gastrointestinal tract is the last to close. Failure of closure results in a persistent vitelline fistula, whereas partial obliteration results in an ileal diverticulum (of Meckel). The ileal diverticulum and umbilical hernia would most likely be repaired at the same time. Other regions (answers a, b, c and e) of the gastrointestinal tract are
unlikely to be attached to the anterior abdominal wall.

6. A 19-year-old teenager is brought to the emergency room after a single-car accident just 20 minutes earlier in which she lost control of her car on black ice and hit a retaining column of an overpass at about 45 miles per hour. She was wearing a seat belt but looks pale, has tachycardia and positional ypotension, is extremely nauseated, and is lying in the fetal position due to increasingly severe abdominal pain. She has no fractures and a cranial nerve test is normal. You order an abdominal CT because you suspect which of the following?

Lacerated kidney

Ruptured spleen

Ruptured gallbladder

Diverticulitis

Hemorrhoids

. (Moore and Dalley, pp 191, 284.) The spleen is a large blood filled organ with a relatively thin capsule that can rupture upon sudden deceleration, causing bleeding into the peritoneal cavity. Appearing pale, the positional hypotension and tachycardia would be consistent with bleeding into the peritoneal cavity, which would lead to generalized abdominal pain, and guarding (answer c). A ruptured gallbladder does not fit with the blood loss symptoms. Neither diverticulitis (answer d) nor
hemorrhoids (answer e) would cause the set of symptoms listed. A lacerated kidney (answer a) would not bring on the sudden onset of symptoms.

Explanation

. (Moore and Dalley, pp 191, 284.) The spleen is a large blood filled organ with a relatively thin capsule that can rupture upon sudden deceleration, causing bleeding into the peritoneal cavity. Appearing pale, the positional hypotension and tachycardia would be consistent with bleeding into the peritoneal cavity, which would lead to generalized abdominal pain, and guarding (answer c). A ruptured gallbladder does not fit with the blood loss symptoms. Neither diverticulitis (answer d) nor
hemorrhoids (answer e) would cause the set of symptoms listed. A lacerated kidney (answer a) would not bring on the sudden onset of symptoms.

7. A 65-year-old male presents with jaundice for 2–3 weeks, fatigue and increasing epigastric pain. He has no history of peptic ulcers and says the pain does not relate to eating in anyway. His epigastric pain is midline and he has had some recent back pain. His urinary bilirubinogen and serum bilirubin are elevated (serum bilirubin 5.8 mg/dl). Helical CT reveals a suspicious mass in the head of the pancreas adjacent to the descending duodenum. The gallbladder is significantly enlarged. Which of the following is the likely cause of the elevated bilirubin?

Viral hepatitis

Blocked cystic duct

Open hepatic duct

Blocked duodenal papilla

Gilbert syndrome

(Moore and Dalley, p 288.) The likely cause of the elevated bilirubin is a blocked pancreatic and bile duct at the duodenal papilla. Pancreatic cancer (usually ductal adenocarcinoma) frequently arises from the head of the pancreas where it blocks the normal flow of bile out of the liver, via the hepatic duct and gallbladder, via the cystic duct which join to form the (common) bile duct that passes through the substance of the head of the pancreas where it joins the main pancreatic duct just before forming the hepatopancreatic ampulla at the second portion of the duodenum (see Moore & Dalley, p 283). As a consequence of the blockage [not open hepatic duct (answer c)] of the normal exit of bile from the body bilirubin levels increase and jaundice (yellowing) develops. Blockage of the cystic duct (answer b) may just lead to a gallbladder enlargement/inflammation. Viral hepatitis (answer a) would normally not be associated with pancreatic cancer. Gilbert syndrome (answer e) is due to mild, chronic unconjugated hyperbilirubinemia and is not involved.

Explanation

(Moore and Dalley, p 288.) The likely cause of the elevated bilirubin is a blocked pancreatic and bile duct at the duodenal papilla. Pancreatic cancer (usually ductal adenocarcinoma) frequently arises from the head of the pancreas where it blocks the normal flow of bile out of the liver, via the hepatic duct and gallbladder, via the cystic duct which join to form the (common) bile duct that passes through the substance of the head of the pancreas where it joins the main pancreatic duct just before forming the hepatopancreatic ampulla at the second portion of the duodenum (see Moore & Dalley, p 283). As a consequence of the blockage [not open hepatic duct (answer c)] of the normal exit of bile from the body bilirubin levels increase and jaundice (yellowing) develops. Blockage of the cystic duct (answer b) may just lead to a gallbladder enlargement/inflammation. Viral hepatitis (answer a) would normally not be associated with pancreatic cancer. Gilbert syndrome (answer e) is due to mild, chronic unconjugated hyperbilirubinemia and is not involved.

8. A woman presents with gallstones and no jaundice. She is prepared for exploratory surgery. The lesser omentum is incised close to its free edge, and the biliary tree is identified and freed by blunt dissection. The liquid contents of the gallbladder are aspirated with a syringe, the fundus incised, and the stones are removed. The entire duct system is carefully probed for stones, one of which is found to be obstructing a duct. In view of her symptoms, where is the most probable location of the obstruction?

The bile duct

The common hepatic duct

The cystic duct

Within the duodenal papilla proximal to the juncture with the pancreatic duct

Within the duodenal papilla distal to the juncture with the pancreatic duct

(Moore and Dalley, p 304.) Obstruction of any portion of the biliary tree will produce symptoms of gallbladder obstruction. If the common hepatic duct (answer b) or bile duct (answer a) is occluded by stone or tumor, biliary stasis with accompanying jaundice occurs. In addition, blockage of the duodenal papilla (of Vater), distal to the juncture of the bile duct with the pancreatic duct (answer e), can lead to complicating pancreatitis. If only the cystic duct is obstructed, jaundice will not occur because bile
may flow freely from the liver to the duodenum. Bile duct obstruction also may arise as a result of pressure exerted on the duct by an external mass, such as a tumor in the head of the pancreas. Answser d is not anatomically correct.

Explanation

(Moore and Dalley, p 304.) Obstruction of any portion of the biliary tree will produce symptoms of gallbladder obstruction. If the common hepatic duct (answer b) or bile duct (answer a) is occluded by stone or tumor, biliary stasis with accompanying jaundice occurs. In addition, blockage of the duodenal papilla (of Vater), distal to the juncture of the bile duct with the pancreatic duct (answer e), can lead to complicating pancreatitis. If only the cystic duct is obstructed, jaundice will not occur because bile
may flow freely from the liver to the duodenum. Bile duct obstruction also may arise as a result of pressure exerted on the duct by an external mass, such as a tumor in the head of the pancreas. Answser d is not anatomically correct.

9. A man, the victim of a superficial knife wound to the lower abdomen during a barroom brawl, subsequently develops a direct inguinal hernia. Damage to which of the following nerves is most likely responsible for the predisposing weakness of the abdominal wall?

Genitofemoral nerve

Ilioinguinal nerve

The subcostal nerve

Pelvic splanchnic nerves

The nerve of the tenth intercostal space (T10)

(Moore and Dalley, pp 202, 207.) The ilioinguinal nerve innervates the portion of the internal oblique muscle inserting in the lateral border of the conjoint tendon. Paralysis of these fibers would create weakness in the conjoint tendon, allowing herniation to occur medial to the inferior epigastric vessels. The genitofemoral nerve (answer a) supplies sensory innervation to the skin of the femoral triangle and scrotum/labia majora. The subcostal nerve (T12) (answer c) supplies lower portions of
the external abdominal oblique muscle. The pelvic splanchnic nerves (answer d) supply autonomic (parasympathetic) innervation to the pelvic viscera. The tenth thoracic spinal nerve (T10) (answer e) supplies abdominal muscles superior to the inguinal region.

Explanation

(Moore and Dalley, pp 202, 207.) The ilioinguinal nerve innervates the portion of the internal oblique muscle inserting in the lateral border of the conjoint tendon. Paralysis of these fibers would create weakness in the conjoint tendon, allowing herniation to occur medial to the inferior epigastric vessels. The genitofemoral nerve (answer a) supplies sensory innervation to the skin of the femoral triangle and scrotum/labia majora. The subcostal nerve (T12) (answer c) supplies lower portions of
the external abdominal oblique muscle. The pelvic splanchnic nerves (answer d) supply autonomic (parasympathetic) innervation to the pelvic viscera. The tenth thoracic spinal nerve (T10) (answer e) supplies abdominal muscles superior to the inguinal region.

10. Sympathectomy may occasionally relieve intractable pain of visceral origin, in as much as visceral afferent pain fibers run along the sympathetic pathways in the abdomen. The autonomic control of peristalsis in the descending colon should not be affected by bilateral lumbar sympathectomy for which of the following reasons?

The descending colon is controlled chiefly by parasympathetic innervation from the pelvic splanchnic nerves

The descending colon receives its parasympathetic innervation from the vagus nerve

The descending colon receives its sympathetic innervation from thoracic splanchnic nerves

Lumbar splanchnics from L1, L2, and L3 only innervate the pelvic viscera via the hypogastric nerve

Only presynaptic sympathetic fibers have been severed

(Moore and Dalley, p 322.) The descending colon is controlled chiefly by parasympathetic innervation from the pelvic splanchnic nerves. Control of peristalsis is principally a function of the parasympathetic division of the autonomic nervous system. Although removal of
the lumbar sympathetic chain (lumbar sympathectomy) does sever the sympathetic fibers innervating the descending colon as well as the pelvic viscera, [not thoracic splanchnics (answer c)] the action of sympathetic fibers to the descending colon is mostly confined to vasoconstriction. Because the parasympathetic innervation to the descending colon is derived from the sacral outflow (S2–S4) through the pelvic splanchnic nerves (nervi erigentes), [not by the vagus (answer b)] peristalsis will occur normally after lumbar sympathectomy. Lumbar splanchnics do not include L3 (answer d). The answer e makes no sense.

Explanation

(Moore and Dalley, p 322.) The descending colon is controlled chiefly by parasympathetic innervation from the pelvic splanchnic nerves. Control of peristalsis is principally a function of the parasympathetic division of the autonomic nervous system. Although removal of
the lumbar sympathetic chain (lumbar sympathectomy) does sever the sympathetic fibers innervating the descending colon as well as the pelvic viscera, [not thoracic splanchnics (answer c)] the action of sympathetic fibers to the descending colon is mostly confined to vasoconstriction. Because the parasympathetic innervation to the descending colon is derived from the sacral outflow (S2–S4) through the pelvic splanchnic nerves (nervi erigentes), [not by the vagus (answer b)] peristalsis will occur normally after lumbar sympathectomy. Lumbar splanchnics do not include L3 (answer d). The answer e makes no sense.

11. A full-term 8 lb baby boy was delivered vaginally to a 36-year-old mother. At delivery he had a large scrotum. The delivering OB palpated the enlarged scrotum and determined that both testicles were present. When the OB pressed gently on the newborn's abdomen the scrotum swelled even more. What congenital condition did the OB note in the chart?

Abdominal hernia

Cryptorchid (maldescended) testes

Varicocele

Hydrocele

Femoral hernia

(Moore and Dalley, pp 225–226.) The newborn boy has a hydrocele. The testicles develop on the posterior abdominal wall and are pulled down and out of the abdominal cavity by the gubernaculum. The final descent through the inguinal canal does not generally occur until the 9th month in utero. The testis remains a retroperitoneal organ behind the fluid-filled space which is connected to the abdominal cavity by the process vaginalis (Moore & Dalley, p 218). In this case the testicles successfully migrated into the scrotum on both sides [so he did not have cryptorchid testes (answer b)], but rather the processus vaginalis failed to seal itself off from the abdominal cavity. Congenital hydrocele normally resolves itself after 2–3 months without any intervention. An abdominal hernia (answer a) is a defect on the anterior abdominal wall and is not present. Varicoceles (answer c) are a stasis of venous blood around the testicle and often present as a bluish scrotal mass. Femoral hernias (answer e) are defects in both the femoral sheath and fascia lata and present on the anterior thigh below the inguinal ligament.

Explanation

(Moore and Dalley, pp 225–226.) The newborn boy has a hydrocele. The testicles develop on the posterior abdominal wall and are pulled down and out of the abdominal cavity by the gubernaculum. The final descent through the inguinal canal does not generally occur until the 9th month in utero. The testis remains a retroperitoneal organ behind the fluid-filled space which is connected to the abdominal cavity by the process vaginalis (Moore & Dalley, p 218). In this case the testicles successfully migrated into the scrotum on both sides [so he did not have cryptorchid testes (answer b)], but rather the processus vaginalis failed to seal itself off from the abdominal cavity. Congenital hydrocele normally resolves itself after 2–3 months without any intervention. An abdominal hernia (answer a) is a defect on the anterior abdominal wall and is not present. Varicoceles (answer c) are a stasis of venous blood around the testicle and often present as a bluish scrotal mass. Femoral hernias (answer e) are defects in both the femoral sheath and fascia lata and present on the anterior thigh below the inguinal ligament.

12. A posteriorly perforating ulcer in the pyloric antrum of the stomach is most likely to produce an initial localized peritonitis or abscess formation in which of the following?

Greater sac

Left subhepatic and hepatorenal spaces (pouch of Morison)

Omental bursa

Right subphrenic space

Right subhepatic space

(Moore and Dalley, pp 239–241, 264.) The omental bursa (lesser sac) is the remnant of the right coelomic cavity, which, owing to rotation of the gut and differential growth of the liver, lies behind the stomach. A posterior gastric perforation or an inflamed pancreas could lead to abscess formation in the lesser sac. The right subhepatic space might become secondarily involved via communication through the omental foramen (of Winslow). The pouch of Morison (answer b), which is the combined right subhepatic (answer d) and the hepatorenal spaces (answer e), may be the seat of abscess formation related to gallbladder disease or perforation of a duodenal ulcer. The right subphrenic space is located between the liver and the diaphragm and communicates with the pouch of Morison. All
these spaces are in communication with the greater sac (answer a) of the peritoneal cavity.

Explanation

(Moore and Dalley, pp 239–241, 264.) The omental bursa (lesser sac) is the remnant of the right coelomic cavity, which, owing to rotation of the gut and differential growth of the liver, lies behind the stomach. A posterior gastric perforation or an inflamed pancreas could lead to abscess formation in the lesser sac. The right subhepatic space might become secondarily involved via communication through the omental foramen (of Winslow). The pouch of Morison (answer b), which is the combined right subhepatic (answer d) and the hepatorenal spaces (answer e), may be the seat of abscess formation related to gallbladder disease or perforation of a duodenal ulcer. The right subphrenic space is located between the liver and the diaphragm and communicates with the pouch of Morison. All
these spaces are in communication with the greater sac (answer a) of the peritoneal cavity.

13. In Hirschsprung's disease, there is a loss of peristalsis in the lower colon and often fatal obstruction. Preganglionic neurons, which would innervate the aganglionic segment of bowel, originate in which of the following?

The nucleus ambiguus

Cervical intermediolateral cell column

Sacral levels two to four of the spinal cord

The motor nucleus of the vagus nerve (CN X)

The ventral horn at spinal levels L1–L2

(Moore and Dalley, p 276.) Preganglionic parasympathetic neurons to the lower colon arise from the spinal cord at sacral levels two to four (thus not answer b) and reach the wall of the colon via pelvic splanchnic nerves. The nucleus ambiguus is the source of preganglionic parasympathetic neurons that innervate the heart via the vagus nerve and cardiac plexus (answer a and d). Neurons arising in the cervical intermediolateral cell column are sympathetic preganglionics. Preganglionic
parasympathetic neurons arising from the motor nucleus of the vagus innervate the upper GI tract. Neurons arising from the ventral horn are primary somatic motor neurons to skeletal muscle (answer e).

Explanation

(Moore and Dalley, p 276.) Preganglionic parasympathetic neurons to the lower colon arise from the spinal cord at sacral levels two to four (thus not answer b) and reach the wall of the colon via pelvic splanchnic nerves. The nucleus ambiguus is the source of preganglionic parasympathetic neurons that innervate the heart via the vagus nerve and cardiac plexus (answer a and d). Neurons arising in the cervical intermediolateral cell column are sympathetic preganglionics. Preganglionic
parasympathetic neurons arising from the motor nucleus of the vagus innervate the upper GI tract. Neurons arising from the ventral horn are primary somatic motor neurons to skeletal muscle (answer e).

14. The 65-year-old with pancreatic adenocarcinoma in the head of pancreas was taken to surgery. A PET CT suggested some metastasis to both liver and multiple posterior lymph nodes. It was explained to the patient and his family that the surgery would likely not be curative, but rather palliative in that the cancer was already too far advanced for removal. During the surgery ablation of the autonomic innervation that carries pain in this region is also performed to provide pain relief. The surgeon will inject 50% ethanol to kill nerve cells at which of the following locations?

At each subcostal nerve under ribs 6–8

Around the celiac trunk

Around each lateral epigastric fold

Around the coronary ligament

Around the lateral arcuate ligament

(Moore and Dalley, pp 284–285, 288.) The surgeon will inject 50% ethanol to kill nerve cells around the celiac trunk. Palliative pain relief for pancreatic cancer is called chemical splanchnicectomy. The purpose is to kill afferent pain fibers which detect free ATP (from dying cells) and stretch receptors for the foregut area, affected by the cancer. This is best accomplished by injecting ethanol around the celiac trunk at the posterior abdominal wall, thus at the celiac plexus. Injection of each subcostal nerve T 6–8 (answer a) would cause a loss of sensation on the upper anterior abdominal wall, but would not cover all the area to which pain is referred. This would be the second best answer. The lateral epigastric folds (answer c) are inferior and only house inferior epigastric blood vessels, not
nerves. The coronary ligament (answer d) holds the liver to the undersurface of the diaphragm. The lateral arcuate ligaments (answer e) are connective tissue structures on the posterior abdominal wall that allow the psoas muscles to pass inferiorly. The whipple procedure (performed in this case) removes the head of the pancreas and much of the duodenum and attaches the gallbladder to the descending portion of the duodenum to relieve the back-up of bile.

Explanation

(Moore and Dalley, pp 284–285, 288.) The surgeon will inject 50% ethanol to kill nerve cells around the celiac trunk. Palliative pain relief for pancreatic cancer is called chemical splanchnicectomy. The purpose is to kill afferent pain fibers which detect free ATP (from dying cells) and stretch receptors for the foregut area, affected by the cancer. This is best accomplished by injecting ethanol around the celiac trunk at the posterior abdominal wall, thus at the celiac plexus. Injection of each subcostal nerve T 6–8 (answer a) would cause a loss of sensation on the upper anterior abdominal wall, but would not cover all the area to which pain is referred. This would be the second best answer. The lateral epigastric folds (answer c) are inferior and only house inferior epigastric blood vessels, not
nerves. The coronary ligament (answer d) holds the liver to the undersurface of the diaphragm. The lateral arcuate ligaments (answer e) are connective tissue structures on the posterior abdominal wall that allow the psoas muscles to pass inferiorly. The whipple procedure (performed in this case) removes the head of the pancreas and much of the duodenum and attaches the gallbladder to the descending portion of the duodenum to relieve the back-up of bile.

15. A 55-year-old woman arrives at the emergency room the day after St. Patrick's Day coughing up bright red blood. She has frequented your emergency room before. History includes excessive alcohol consumption. Using abdominal percussion you determine that her liver extends 5 cm below the right costal margin at the midclavicular line. You call in a gastroenterologist because you suspect that the bright red blood is most likely the result of which of the following?

Hemorrhoids

Colon cancer

Duodenal ulcer

Gastric ulcer

Esophageal varices

(Moore and Dalley, pp 305–307.) Because of an enlarged liver and the history of excessive alcohol consumption, you suspect cirrhosis of the liver, which resulted in portal hypertension. Because the blood is bright red, suggesting that it has not been exposed to duodenal or gastric secretions, the most likely source would be esophageal varices, as blood is trying to return from the portal system to the systemic circulatory system. Hemorrhoids (answer a) are commonly associated with cirrhosis of the liver, but at the other end of the GI tract. Colon cancer (answer b) does not present with upper GI bleed, rather lower GI bleeding. Neither duodenal (answer c) nor gastric ulcers (answer d) present with bright red blood.

Explanation

(Moore and Dalley, pp 305–307.) Because of an enlarged liver and the history of excessive alcohol consumption, you suspect cirrhosis of the liver, which resulted in portal hypertension. Because the blood is bright red, suggesting that it has not been exposed to duodenal or gastric secretions, the most likely source would be esophageal varices, as blood is trying to return from the portal system to the systemic circulatory system. Hemorrhoids (answer a) are commonly associated with cirrhosis of the liver, but at the other end of the GI tract. Colon cancer (answer b) does not present with upper GI bleed, rather lower GI bleeding. Neither duodenal (answer c) nor gastric ulcers (answer d) present with bright red blood.

16. Many cesarean sections are performed by making a horizontal skin incision that is slightly curved (about 15 cm) on the anterior abdominal wall just superior to the pubic hairline (bikini or Pfannerenstiel incision). However, this incision is often only made through the skin down to the perimysium of the rectus abdominis muscle. Which of the following cutaneous nerves are at greatest risk with this type of incision?

Thoracoabdominal (intercostal) nerve (T 10)

Thoracoabdominal (intercostal) nerve (T 11)

Iliohypogastric nerve (L1)

Ilioinguinal nerve (L1)

Lateral (femoral) cutaneous nerve of the thigh (L2–3)

(Moore and Dalley, pp 207, 209.) The cutaneous nerves are at risk with this type of incision is the iliohypogastric nerve (L1). The thoracoabdominal (intercostal) nerve T10 (answer a) generally supplies the dermatome that includes the umbilicus while the skin over the inguinal ligament is generally served by the L1 spinal level. T11 (answer b) is also too cranial to be a risk of injury. Both the subcostal nerve T12 (not listed as choice) and the iliohypogastric nerves are likely cut during the Pfannerenstiel incision. The ilioinguinal nerve (answer d) tends to course about an inch superior to the inguinal ligament, thus usually would most likely not be cut. The lateral (femoral) cutaneous nerve of the thigh (from L2 to L3) (answer e) runs across the iliacus muscle and under the inguinal ligament well lateral to the femoral sheath to serve the anterolateral aspect of the thigh, thus should not be at risk.

Explanation

(Moore and Dalley, pp 207, 209.) The cutaneous nerves are at risk with this type of incision is the iliohypogastric nerve (L1). The thoracoabdominal (intercostal) nerve T10 (answer a) generally supplies the dermatome that includes the umbilicus while the skin over the inguinal ligament is generally served by the L1 spinal level. T11 (answer b) is also too cranial to be a risk of injury. Both the subcostal nerve T12 (not listed as choice) and the iliohypogastric nerves are likely cut during the Pfannerenstiel incision. The ilioinguinal nerve (answer d) tends to course about an inch superior to the inguinal ligament, thus usually would most likely not be cut. The lateral (femoral) cutaneous nerve of the thigh (from L2 to L3) (answer e) runs across the iliacus muscle and under the inguinal ligament well lateral to the femoral sheath to serve the anterolateral aspect of the thigh, thus should not be at risk.

17. The lateral umbilical fold serves as the demarcation for whether an inguinal hernia is direct or indirect. The lateral umbilical fold on each side of the inner surface of the anterior abdominal wall is created by which of the following underlying structures?

Falx inguinalis

Inferior epigastric artery

Lateral border of the rectus sheath

Obliterated umbilical artery

Urachus

(Moore and Dalley, p 231.) Inferior epigastric artery. The lateral umbilical folds are produced by the underlying inferior epigastric arteries as they course from the external iliac artery in the inguinal region toward the rectus sheath. A direct inguinal hernia starts medial to the lateral ambilical fold and an indirect inguinal hernia starts lateral to the same fold. The medial umbilical folds are peritoneal elevations produced by the obliterated umbilical arteries (answer d). In the midline, the median umbilical ligament is formed by the underlying urachus (answer e), a remnant of the embryonic allantois. The Falx inguinalis (answer a) represents inferomedial attachment of transversus abdominis with some fibers of internal abdominal oblique, also known as: conjoint tendon. The lateral border of the rectus sheath (answer c) forms the medial edge of the inguinal triangle.

Explanation

(Moore and Dalley, p 231.) Inferior epigastric artery. The lateral umbilical folds are produced by the underlying inferior epigastric arteries as they course from the external iliac artery in the inguinal region toward the rectus sheath. A direct inguinal hernia starts medial to the lateral ambilical fold and an indirect inguinal hernia starts lateral to the same fold. The medial umbilical folds are peritoneal elevations produced by the obliterated umbilical arteries (answer d). In the midline, the median umbilical ligament is formed by the underlying urachus (answer e), a remnant of the embryonic allantois. The Falx inguinalis (answer a) represents inferomedial attachment of transversus abdominis with some fibers of internal abdominal oblique, also known as: conjoint tendon. The lateral border of the rectus sheath (answer c) forms the medial edge of the inguinal triangle.

18. A slender 53-year-old woman who smokes a pack of cigarettes each day comes to your office complaining of a pulsating sensation in her abdomen with generalized abdominal and back pain. You palpate her abdomen and feel a mid-line pulse with every heart beat. You order an abdominal Doppler ultrasound, which shows a large, high abdominal aortic aneurysm above renal arteries of about 8 cm in diameter. She is admitted to the hospital immediately for repair of her aortic aneurysm because it is life threatening, but you warn her that one of the complications of such surgical repair includes paraplegia. During the procedure the vascular surgeon must completely clamp off the abdominal aorta for about an hour while repairing the aneurysm. Which of the following would explain to the patient why there is a risk of paraplegia?

Stopping the blood within the abdominal aorta causes the muscle of the lower limbs to die

Stopping the blood within the abdominal aorta causes the peripheral nerves of the lower limb to die

(Moore and Dalley, pp 528–530.) The lower thoracic and upper lumbar portion of the spinal cord tend to receive a single major radicular artery (of Adamkiewicz), which supplies blood to the anterior longitudinally running spinal artery. The anterior spinal artery mainly supplies the anterior two-thirds of the spinal cord in this region, which includes motor neurons that control the lower limbs. Because the metabolic needs of the spinal cord nerves are so great, the lack of blood during the surgery can lead to nerve cell death and thus paraplegia. Both muscle and peripheral nerves generally can survive the temporary disruption in blood flow. A process of cooling the spinal cord, by perfusing ice cold saline
into the extradural space (called epidural cooling), is often performed to reduce the metabolic needs of the spinal nerves, thus often preventing central nervous system cell death during the surgical procedure. Muscles (answer a) and nerves (answer b) of the lower limb can survive reduced blood flow for an hour. Microemboli would not selectively locate in the motor cortex (answer d). Bleeding strokes in the motor cortex are unlikely (answer e).

Explanation

(Moore and Dalley, pp 528–530.) The lower thoracic and upper lumbar portion of the spinal cord tend to receive a single major radicular artery (of Adamkiewicz), which supplies blood to the anterior longitudinally running spinal artery. The anterior spinal artery mainly supplies the anterior two-thirds of the spinal cord in this region, which includes motor neurons that control the lower limbs. Because the metabolic needs of the spinal cord nerves are so great, the lack of blood during the surgery can lead to nerve cell death and thus paraplegia. Both muscle and peripheral nerves generally can survive the temporary disruption in blood flow. A process of cooling the spinal cord, by perfusing ice cold saline
into the extradural space (called epidural cooling), is often performed to reduce the metabolic needs of the spinal nerves, thus often preventing central nervous system cell death during the surgical procedure. Muscles (answer a) and nerves (answer b) of the lower limb can survive reduced blood flow for an hour. Microemboli would not selectively locate in the motor cortex (answer d). Bleeding strokes in the motor cortex are unlikely (answer e).

19. A 46-year-old bakery worker is admitted to a hospital in acute distress. She has experienced severe abdominal pain, nausea, and vomiting for 2 days. The pain, which is sharp and constant, began in the epigastric region and radiated bilaterally around the chest to just below the scapulas. Subsequently, the pain became localized in the right hypochondrium. The patient, who has a history of similar but milder attacks after hearty meals over the past 5 years, is moderately overweight and the mother of four. Palpation reveals marked tenderness in the right hypochondriac region and some rigidity of the abdominal musculature. An x-ray without contrast medium shows numerous calcified stones in the region of the gallbladder. The patient shows no sign of jaundice (icterus). Diffuse pain referred to the epigastric region and radiating circumferentially around the chest is the result of afferent fibers that travel via which of the following nerves?

Greater splanchnic

Intercostal

Phrenic

Vagus

Pelvic splanchnics

Moore and Dalley, pp 257–258, 322–323.) Visceral afferent pain fibers from the gallbladder travel through the celiac plexus, thence along the greater splanchnic nerves to levels T5–T9 of the spinal cord. Thus, pain originating from the gallbladder will be referred to (appear as if coming from) the dermatomes served by T5–T9, which include a band from the infrascapular region to the epigastrium. If the gallbladder enlarges sufficiently, then pain could be carried by the phrenic nerve (answer c), but this would refer pain to the neck. Intercostal nerves (answer b) would course above the diaphragm and thus are not involved. The vagus (answer d) generally does not transmit pain information. Pelvic splanchinics (answers e) receive pain information from pelvic organs and thus are not involved.

Explanation

Moore and Dalley, pp 257–258, 322–323.) Visceral afferent pain fibers from the gallbladder travel through the celiac plexus, thence along the greater splanchnic nerves to levels T5–T9 of the spinal cord. Thus, pain originating from the gallbladder will be referred to (appear as if coming from) the dermatomes served by T5–T9, which include a band from the infrascapular region to the epigastrium. If the gallbladder enlarges sufficiently, then pain could be carried by the phrenic nerve (answer c), but this would refer pain to the neck. Intercostal nerves (answer b) would course above the diaphragm and thus are not involved. The vagus (answer d) generally does not transmit pain information. Pelvic splanchinics (answers e) receive pain information from pelvic organs and thus are not involved.

20. An 11-year-old girl is brought into your pediatric office by her mother. She recently learned to do back flips on the balance beam, when her foot slipped off and she landed with her perineum striking the beam. She developed a massive subcutaneous hematoma filling her perineum that posteriorly formed a straight horizontal line just anterior to her anus, and anteriorly extended onto the anterior abdominal wall about half way up to her umbilicus and above the inguinal ligament. No blood entered her thighs. She could still urinate and there was no blood in her urine. The hematoma was contained by what space?

Ischioanal fossa

Superficial perineal space

Deep perineal space

Femoral sheath

Inguinal canal

(Moore and Dalley, pp 440–442.) The hematoma was contained by superficial perineal space. This is a typical “straddle” injury to the perineum. The blood is collecting in the superficial perineal space, which houses the erectile tissue and is created by the superficial membranous fascia (see Moore & Dalley, p 440), which is called Scarpa’s on the anterior abdominal wall (where it is attached half way up to the rectus abdominis muscle sheath) and is called Colles’ fascia in the perineum. The membranous fascia attaches (deep) to the perineal membrane posteriorly and to the fascia lata of thigh and inguinal ligament. In males the membranous fascia has three names: Scarpa’s (anterior abdominal wall); Dartos on penis and scrotum and Colles’ on perineum. Following straddle injuries blood does not enter the inguinal canal (answer e), femoral sheath (answer d) and ischioanal fossa (answer a). The deep perineal space (answer c) is deep to the perineal membrane.

Explanation

(Moore and Dalley, pp 440–442.) The hematoma was contained by superficial perineal space. This is a typical “straddle” injury to the perineum. The blood is collecting in the superficial perineal space, which houses the erectile tissue and is created by the superficial membranous fascia (see Moore & Dalley, p 440), which is called Scarpa’s on the anterior abdominal wall (where it is attached half way up to the rectus abdominis muscle sheath) and is called Colles’ fascia in the perineum. The membranous fascia attaches (deep) to the perineal membrane posteriorly and to the fascia lata of thigh and inguinal ligament. In males the membranous fascia has three names: Scarpa’s (anterior abdominal wall); Dartos on penis and scrotum and Colles’ on perineum. Following straddle injuries blood does not enter the inguinal canal (answer e), femoral sheath (answer d) and ischioanal fossa (answer a). The deep perineal space (answer c) is deep to the perineal membrane.

21. Mucosal necrosis of the rectum usually will not result from occlusion of the inferior mesenteric artery for which of the following reasons?

Arterial supply to the rectum is from anastomotic connections from the superior mesenteric artery

Arterial supply to the rectum is from the left colic artery with anastomoses to branches of the internal iliac artery

The inferior mesenteric artery does not supply the rectum

A principal branch of the external iliac artery is a major supplier to the rectum

The middle rectal artery, a branch of the internal iliac artery, supplies the rectum

(Moore and Dalley, p 430.) The rectum receives blood from the superior rectal (hemorrhoidal) artery and from the paired middle and inferior rectal arteries. The superior rectal artery is a direct continuation of the inferior mesenteric artery, but the middle and inferior rectal arteries are branches of the internal iliac artery and continue to supply the distal rectum despite occlusion of the inferior mesenteric artery. It should be noted that Sudeck’s point, between the last sigmoidal artery and the rectosigmoid artery, is an area of potentially weak arterial anastomoses, but that is further cranial. The superior mesenteric artery (answer a) distributes arteries to the small intestine right and middle colic arteries, that supply blood as far distal as the splenic flexure of the transverse colon. The left colic artery (answer b) anastomoses with the sigmoidal arteries. The inferior mesenteric artery supplies the superior rectal artery, so answer c is not correct. The principal branch of the external iliac artery is the femoral
artery (answer e).

Explanation

(Moore and Dalley, p 430.) The rectum receives blood from the superior rectal (hemorrhoidal) artery and from the paired middle and inferior rectal arteries. The superior rectal artery is a direct continuation of the inferior mesenteric artery, but the middle and inferior rectal arteries are branches of the internal iliac artery and continue to supply the distal rectum despite occlusion of the inferior mesenteric artery. It should be noted that Sudeck’s point, between the last sigmoidal artery and the rectosigmoid artery, is an area of potentially weak arterial anastomoses, but that is further cranial. The superior mesenteric artery (answer a) distributes arteries to the small intestine right and middle colic arteries, that supply blood as far distal as the splenic flexure of the transverse colon. The left colic artery (answer b) anastomoses with the sigmoidal arteries. The inferior mesenteric artery supplies the superior rectal artery, so answer c is not correct. The principal branch of the external iliac artery is the femoral
artery (answer e).

22. The lesser sac (omental bursa) is directly continuous with which of the following recesses or spaces?

Infracolic compartment

Left colic gutter

Left subphrenic recess

Right subphrenic space

Hepatorenal recess

(Moore and Dalley, p 290.) The omental (epiploic) foramen connects the lesser sac with the hepatorenal (subhepatic) recess of the greater sac (see Moore and Dalley, p 290 for an excellent picture of this relationship). The hepatorenal recess then communicates with the right subphrenic recess and right paracolic gutter. The subhepatic recess is perhaps the most frequently infected intra-abdominal space as a result of appendicitis, liver abscess, perforated duodenal and gastric ulcers, or perforation of the biliary tree. The infracolic compartment is (answer a) part of the greater omentum. The left colic gutter (answer b) is further inferior and left. The left subphrenic recess (answer c) and right subphrenic space (answer d) are further cranial on top of the liver.

Explanation

(Moore and Dalley, p 290.) The omental (epiploic) foramen connects the lesser sac with the hepatorenal (subhepatic) recess of the greater sac (see Moore and Dalley, p 290 for an excellent picture of this relationship). The hepatorenal recess then communicates with the right subphrenic recess and right paracolic gutter. The subhepatic recess is perhaps the most frequently infected intra-abdominal space as a result of appendicitis, liver abscess, perforated duodenal and gastric ulcers, or perforation of the biliary tree. The infracolic compartment is (answer a) part of the greater omentum. The left colic gutter (answer b) is further inferior and left. The left subphrenic recess (answer c) and right subphrenic space (answer d) are further cranial on top of the liver.