Abdominal radiologic landmarks US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Abdominal radiologic landmarks. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Abdominal radiologic landmarks US Medical PG Question 1: A 34-year-old patient presents with severe pain in the right upper quadrant that radiates to the right shoulder. During laparoscopic cholecystectomy, which of the following anatomical spaces must be carefully identified to prevent bile duct injury?
- A. Foramen of Winslow
- B. Lesser sac
- C. Calot's triangle (Correct Answer)
- D. Morrison's pouch
Abdominal radiologic landmarks Explanation: ***Calot's triangle***
- **Calot's triangle** is the critical anatomical landmark containing the **cystic artery** and **cystic duct**, whose proper identification is essential to prevent injury to the hepatic artery or bile ducts during cholecystectomy.
- Its boundaries are the **cystic duct** (lateral), the **common hepatic duct** (medial), and the **inferior border of the liver** (superior, sometimes described as the cystic artery).
*Foramen of Winslow*
- The **Foramen of Winslow** (epiploic foramen) is an opening connecting the **greater and lesser sacs** of the peritoneal cavity.
- It is not directly relevant to identifying structures during cholecystectomy, but rather to accessing the lesser sac or for surgical procedures involving structures like the portal triad.
*Lesser sac*
- The **lesser sac** (omental bursa) is a peritoneal cavity posterior to the stomach and lesser omentum.
- It is explored in procedures involving the pancreas, posterior gastric wall, or for assessing fluid collections, but not for direct identification of cystic structures during standard cholecystectomy.
*Morrison's pouch*
- **Morrison's pouch** is the **hepatorenal recess**, a potential space between the posterior aspect of the liver and the right kidney and adrenal gland.
- It is a common site for **fluid accumulation** (e.g., ascites, blood) but is not directly incised or dissected for preventing bile duct injury during cholecystectomy.
Abdominal radiologic landmarks US Medical PG Question 2: During a surgical procedure to repair an abdominal aortic aneurysm, the surgeon must be careful to avoid injury to which of the following arterial structures that originates near the level of the renal vessels?
- A. Left renal artery (Correct Answer)
- B. Celiac trunk
- C. Right renal artery
- D. Superior mesenteric artery
Abdominal radiologic landmarks Explanation: ***Left renal artery***
- The **left renal artery** arises from the aorta usually just below the superior mesenteric artery, making it susceptible to injury during an **abdominal aortic aneurysm (AAA) repair** if the aneurysm extends proximally.
- Its proximity to the typical location of AAA, often near or involving the **infrarenal aorta**, necessitates careful identification and protection during clamping or graft placement.
*Celiac trunk*
- The **celiac trunk** originates higher up from the aorta, typically at the level of **T12-L1 vertebrae**, well above the common infrarenal AAA repair site.
- While important, it is generally less directly threatened during a typical infrarenal AAA repair compared to arteries immediately adjacent to or within the aneurysm sac.
*Right renal artery*
- The **right renal artery** also originates from the aorta near the level of the renal veins, but it is typically located more posteriorly and usually passes behind the inferior vena cava.
- Although it can be at risk, the left renal artery's course is often more anterior and directly in the field of dissection for the **aortic neck** during AAA repair.
*Superior mesenteric artery*
- The **superior mesenteric artery (SMA)** originates from the aorta proximal to the renal arteries, typically around the L1 vertebral level.
- While crucial, its origin is usually cephalad to the infrarenal aneurysm neck, making it generally less prone to direct injury during infrarenal AAA repair, though flow must be monitored.
Abdominal radiologic landmarks US Medical PG Question 3: A 12-year-old boy is brought to the emergency department late at night by his worried mother. She says he has not been feeling well since this morning after breakfast. He skipped both lunch and dinner. He complains of abdominal pain as he points towards his lower abdomen but says that the pain initially started at the center of his belly. His mother adds that he vomited once on the way to the hospital. His past medical history is noncontributory and his vaccinations are up to date. His temperature is 38.1°C (100.6°F), pulse is 98/min, respirations are 20/min, and blood pressure is 110/75 mm Hg. Physical examination reveals right lower quadrant tenderness. The patient is prepared for laparoscopic abdominal surgery. Which of the following structures is most likely to aid the surgeons in finding the source of this patient's pain and fever?
- A. McBurney's point
- B. Linea Semilunaris
- C. Transumbilical plane
- D. Arcuate line
- E. Teniae coli (Correct Answer)
Abdominal radiologic landmarks Explanation: ***Teniae coli***
- The **teniae coli** are three distinct longitudinal bands of smooth muscle that run along the length of the large intestine, converging at the base of the appendix. They serve as reliable anatomical landmarks for locating the appendix during surgery.
- Given the patient's symptoms (periumbilical pain migrating to the right lower quadrant, fever, vomiting, and right lower quadrant tenderness), **acute appendicitis** is highly suspected, making the teniae coli crucial for surgical identification of the inflamed appendix.
*McBurney's point*
- **McBurney's point** is a clinical landmark on the abdominal wall, two-thirds of the way from the umbilicus to the right anterior superior iliac spine, that often corresponds to the base of the appendix. It is used to elicit tenderness during physical examination.
- While tenderness at McBurney's point is a strong indicator of appendicitis, it is a **surface landmark** for diagnosis and not an internal anatomical structure that aids the surgeon in _finding_ the appendix during a laparoscopic procedure.
*Linea Semilunaris*
- The **linea semilunaris** is the curved tendinous intersection found at the lateral border of the rectus abdominis muscle, extending from the costal margin to the pubic tubercle.
- It defines the lateral extent of the rectus sheath but has **no direct anatomical relationship** to the appendix or its surgical identification.
*Transumbilical plane*
- The **transumbilical plane** is an imaginary horizontal plane passing through the umbilicus. It is used in topographical anatomy for abdominal segmentation.
- It is a **surface and arbitrary anatomical plane** for regional description, not an internal structure that guides surgical access to or identification of the appendix.
*Arcuate line*
- The **arcuate line** is a crescent-shaped anatomical landmark located on the posterior wall of the rectus sheath, inferior to the umbilicus, marking the transition where the aponeuroses of the transverse abdominis and internal oblique muscles pass anterior to the rectus abdominis.
- This line is relevant to the integrity of the rectus sheath but is **anatomically distant from the appendix** and does not assist in its surgical localization.
Abdominal radiologic landmarks US Medical PG Question 4: A 65-year-old woman with atrial fibrillation comes to the emergency department because of sudden-onset severe abdominal pain, nausea, and vomiting for the past 2 hours. She has smoked a pack of cigarettes daily for the past 25 years. Her pulse is 110/min and blood pressure is 141/98 mm Hg. Abdominal examination shows diffuse abdominal tenderness without guarding or rebound. A CT angiogram of the abdomen confirms an acute occlusion in the inferior mesenteric artery. Which of the following structures of the gastrointestinal tract is most likely to be affected in this patient?
- A. Hepatic flexure
- B. Rectosigmoid colon (Correct Answer)
- C. Ascending colon
- D. Transverse colon
- E. Lower rectum
Abdominal radiologic landmarks Explanation: ***Rectosigmoid colon***
- The **inferior mesenteric artery (IMA)** supplies the distal third of the transverse colon, descending colon, sigmoid colon, and superior part of the rectum, which includes the **rectosigmoid colon**.
- The **rectosigmoid region** is entirely dependent on IMA branches (sigmoid arteries and superior rectal artery) and represents a classic watershed area vulnerable to ischemia.
- An occlusion in the IMA would compromise blood flow to these structures, leading to ischemia and symptoms like severe abdominal pain, bloody diarrhea, and peritoneal signs.
*Hepatic flexure*
- The **hepatic flexure** is primarily supplied by branches of the **superior mesenteric artery (SMA)**, specifically the middle colic artery.
- An occlusion in the IMA would generally spare the hepatic flexure, as its blood supply comes from a different major arterial system.
*Ascending colon*
- The **ascending colon** receives its blood supply from the **superior mesenteric artery (SMA)** via the ileocolic and right colic arteries.
- Therefore, an occlusion in the IMA would not directly affect the blood supply to the ascending colon.
*Transverse colon*
- While the **IMA** supplies the **distal one-third of the transverse colon** via the left colic artery, the term "transverse colon" as an anatomical structure includes both IMA and SMA territories.
- The proximal two-thirds are supplied by the **superior mesenteric artery (SMA)** via the middle colic artery, with robust collateral circulation through the marginal artery of Drummond.
- The rectosigmoid colon is the more specific and entirely IMA-dependent structure, making it the most likely to be affected.
*Lower rectum*
- The **lower rectum** receives its blood supply primarily from the **internal iliac arteries** via the middle and inferior rectal arteries.
- The IMA supplies the superior part of the rectum, but the lower rectum has a separate and robust blood supply, making it less likely to be affected by an isolated IMA occlusion.
Abdominal radiologic landmarks US Medical PG Question 5: A patient undergoes spinal surgery at the L4-L5 level. During the procedure, which of the following ligaments must be divided first to access the spinal canal?
- A. Nuchal ligament
- B. Anterior longitudinal ligament
- C. Supraspinous ligament
- D. Ligamentum flavum (Correct Answer)
Abdominal radiologic landmarks Explanation: ***Ligamentum flavum***
- The **ligamentum flavum** connects the laminae of adjacent vertebrae and forms the posterior boundary of the spinal canal, making it the first ligament encountered anteriorly after removing the lamina.
- While performing a posterior approach **laminectomy**, the ligamentum flavum is typically divided or removed to gain access to the neural structures within the spinal canal.
*Nuchal ligament*
- The **nuchal ligament** is located in the cervical spine and provides attachment for muscles, extending from the external occipital protuberance to the spinous process of C7.
- It is not present at the **L4-L5 level** and therefore plays no role in lumbar spinal surgery.
*Anterior longitudinal ligament*
- The **anterior longitudinal ligament** runs along the anterior surfaces of the vertebral bodies and intervertebral discs.
- It would be encountered during an **anterior surgical approach** to the spine, not a posterior approach to access the spinal canal.
*Supraspinous ligament*
- The **supraspinous ligament** connects the tips of the spinous processes and is the most superficial ligament posteriorly.
- While it is incised during a posterior approach, it is **superficial to the lamina** and ligamentum flavum; therefore, the lamina and ligamentum flavum must be removed or divided first to access the canal.
Abdominal radiologic landmarks US Medical PG Question 6: A 65-year-old man presents to the emergency department with vague, constant abdominal pain, and worsening shortness of breath for the past several hours. He has baseline shortness of breath and requires 2–3 pillows to sleep at night. He often wakes up because of shortness of breath. Past medical history includes congestive heart failure, diabetes, hypertension, and hyperlipidemia. He regularly takes lisinopril, metoprolol, atorvastatin, and metformin. His temperature is 37.0°C (98.6°F), respiratory rate 25/min, pulse 67/min, and blood pressure 98/82 mm Hg. On physical examination, he has bilateral crackles over both lung bases and a diffusely tender abdomen. His subjective complaint of abdominal pain is more severe than the observed tenderness on examination. Which of the following vessels is involved in the disease affecting this patient?
- A. Left anterior descending
- B. Celiac artery and superior mesenteric artery (Correct Answer)
- C. Left colic artery
- D. Right coronary artery
- E. Meandering mesenteric artery
Abdominal radiologic landmarks Explanation: **Celiac artery and superior mesenteric artery**
- The patient's presentation with **vague, constant abdominal pain** out of proportion to physical exam findings (**abdominal pain more severe than tenderness**) in the setting of **congestive heart failure** and **hypotension** is highly suggestive of **non-occlusive mesenteric ischemia (NOMI)**.
- NOMI results from **splanchnic vasoconstriction** leading to hypoperfusion of the bowel, primarily affecting the territories supplied by the **celiac artery** and **superior mesenteric artery**, which supply the foregut and midgut, respectively.
*Left anterior descending*
- The left anterior descending (LAD) artery primarily supplies the **left ventricle** and interventricular septum.
- Occlusion of the LAD typically causes a **myocardial infarction** with chest pain, EKG changes, and elevated cardiac enzymes, which is not the primary presentation here, although a degree of cardiac compromise exacerbates the NOMI.
*Left colic artery*
- The left colic artery is a branch of the **inferior mesenteric artery** and supplies portions of the **descending colon**.
- While bowel ischemia can affect this region, NOMI, a more widespread condition, is unlikely to be isolated to the left colic artery distribution, and the patient's symptoms are more consistent with multi-vessel involvement.
*Right coronary artery*
- The right coronary artery (RCA) supplies the **right ventricle**, inferior wall of the left ventricle, and often the **SA and AV nodes**.
- RCA occlusion typically leads to **inferior wall myocardial infarction** and can cause bradyarrhythmias, but it would not directly cause the described abdominal pain and out-of-proportion findings.
*Meandering mesenteric artery*
- The meandering mesenteric artery is an anatomical variant, an **anastomotic connection** between the superior and inferior mesenteric arteries.
- While it can be a source of collateral flow, it is not a primary vessel targeted in the pathogenesis of NOMI, which affects the main mesenteric arteries due to global hypoperfusion.
Abdominal radiologic landmarks US Medical PG Question 7: A 24-year-old man presents to the emergency department after a motor vehicle accident. The patient was at a stop when he was rear-ended from behind by a vehicle traveling at 11 miles per hour. The patient complains of severe back pain but states he otherwise feels well. The patient is currently seeing a physical therapist who is giving him exercises to alleviate the back pain that is present every morning, relived by activity, and worse with inactivity. He is a student at the university and is struggling with his grades. His temperature is 98.4°F (36.9°C), blood pressure is 117/78 mmHg, pulse is 116/min, respirations are 12/min, and oxygen saturation is 99% on room air. Physical exam demonstrates a decreased range of motion of the patient's spine and tenderness to palpation over the vertebrae. The rest of the exam is deferred due to pain. The patient is requesting a note to excuse him from final exams and work. Which of the following is the most likely diagnosis in this patient?
- A. Spondylolisthesis
- B. Malingering
- C. Herniated nucleus pulposus
- D. Vertebral fracture
- E. Musculoskeletal strain (Correct Answer)
Abdominal radiologic landmarks Explanation: ***Musculoskeletal strain***
- The patient has a **pre-existing chronic back pain condition** (morning stiffness relieved by activity) that is being managed with physical therapy, suggesting a baseline musculoskeletal issue.
- The **low-speed motor vehicle accident** (11 mph) is unlikely to cause significant structural injury and more likely represents an **acute-on-chronic exacerbation** of his underlying musculoskeletal condition.
- While the chronic pattern (morning stiffness, improved with activity) raises consideration for inflammatory spondyloarthropathy, among the options provided, musculoskeletal strain best captures the **acute exacerbation of chronic mechanical back pain** in the context of minor trauma.
- The patient's request for excuse from exams may represent legitimate need for rest or possible secondary gain, but does not change the primary musculoskeletal diagnosis.
*Spondylolisthesis*
- This involves **anterior slippage of one vertebra over another** and typically presents with mechanical back pain that worsens with **extension and activity** (not relieved by activity as in this patient).
- There is no mention of the characteristic **step-off deformity** on palpation or radicular symptoms that often accompany symptomatic spondylolisthesis.
- The patient's chronic pain pattern of improvement with activity argues against this diagnosis.
*Malingering*
- **Malingering** involves intentional fabrication or gross exaggeration of symptoms for external gain (avoiding exams/work).
- However, this patient has **documented chronic back pain** with ongoing physical therapy, suggesting real underlying pathology rather than pure fabrication.
- While secondary gain may be a factor, the presence of actual pre-existing symptoms and objective findings (decreased ROM, tenderness) makes pure malingering less likely.
*Herniated nucleus pulposus*
- A **herniated disc** typically presents with acute **radicular pain** radiating into the lower extremities, often with neurological deficits (weakness, numbness, reflex changes).
- This patient's presentation is primarily **axial back pain** without mention of leg pain, paresthesias, or neurological deficits, making HNP unlikely.
- The chronic nature and activity-related improvement pattern is atypical for acute disc herniation.
*Vertebral fracture*
- **Vertebral compression fractures** require either significant trauma or underlying bone pathology (osteoporosis, malignancy).
- The **low-speed impact** (11 mph rear-end collision) in a young, otherwise healthy 24-year-old male is insufficient mechanism for vertebral fracture.
- While there is tenderness over vertebrae, the patient's stable vital signs (aside from mild tachycardia likely from pain/anxiety) and absence of neurological compromise make acute fracture very unlikely.
Abdominal radiologic landmarks US Medical PG Question 8: A CT scan of the abdomen reveals a mass in the pancreatic uncinate process. Which of the following structures is most likely to be compressed by this mass?
- A. Common bile duct
- B. Portal vein
- C. Splenic vein
- D. Superior mesenteric vein (Correct Answer)
Abdominal radiologic landmarks Explanation: ***Superior mesenteric vein***
- The **uncinate process** of the pancreas hooks around the **superior mesenteric vessels**. Therefore, a mass in this region would most directly compress the **superior mesenteric vein (SMV)** and artery (SMA).
- Compression of the SMV can lead to **venous outflow obstruction** from the small intestine, potentially causing **bowel ischemia** or edema.
*Common bile duct*
- The **common bile duct** passes through the **head of the pancreas**, not typically the uncinate process.
- Compression of the common bile duct would more commonly be associated with masses in the **head of the pancreas**, leading to **jaundice**.
*Portal vein*
- The **portal vein** is formed by the union of the **splenic vein** and the **superior mesenteric vein**, generally posterior to the neck of the pancreas.
- While pancreatic masses can affect the portal vein, a mass specifically in the uncinate process would more directly impinge on the SMV before significantly affecting the main portal vein, which is superior and posterior to the uncinate process.
*Splenic vein*
- The **splenic vein** runs along the **posterior aspect of the body and tail of the pancreas**.
- A mass in the uncinate process, located at the inferior margin of the head, is relatively distant from the splenic vein.
Abdominal radiologic landmarks US Medical PG Question 9: A 24-year-old woman comes to the emergency department because of abdominal pain, fever, nausea, and vomiting for 12 hours. Her abdominal pain was initially dull and diffuse but has progressed to a sharp pain on the lower right side. Two years ago she had to undergo right salpingo-oophorectomy after an ectopic pregnancy. Her temperature is 38.7°C (101.7°F). Physical examination shows severe right lower quadrant tenderness with rebound tenderness; bowel sounds are decreased. Laboratory studies show leukocytosis with left shift. An abdominal CT scan shows a distended, edematous appendix. The patient is taken to the operating room for an appendectomy. During the surgery, the adhesions from the patient's previous surgery make it difficult for the resident physician to identify the appendix. Her attending mentions that she should use a certain structure for guidance to locate the appendix. The attending is most likely referring to which of the following structures?
- A. Epiploic appendages
- B. Right ureter
- C. Deep inguinal ring
- D. Ileocolic artery
- E. Teniae coli (Correct Answer)
Abdominal radiologic landmarks Explanation: ***Teniae coli***
- The **teniae coli** are three distinct longitudinal bands of smooth muscle that run along the length of the cecum and colon, converging at the base of the **appendix**.
- Following these bands inferiorly from the ascending colon or cecum during surgery is a reliable method to locate the **vermiform appendix**, especially in the presence of adhesions.
*Epiploic appendages*
- These are small, fat-filled sacs that protrude from the surface of the **large intestine** but are not directly used as a reliable landmark for locating the appendix.
- While present in the vicinity, they do not consistently lead to the base of the appendix like the teniae coli.
*Right ureter*
- The **right ureter** is located retroperitoneally, deep to the cecum and appendix, and is not a direct anatomical landmark used for identifying the appendix during an appendectomy.
- Identifying the ureter is important to avoid injury, but not for localizing the appendix.
*Deep inguinal ring*
- The **deep inguinal ring** is an opening in the transversalis fascia, involved in the formation of the inguinal canal, and is located far anterior and inferior to the region of the appendix.
- It has no anatomical relationship that would guide a surgeon to locate the appendix.
*Ileocolic artery*
- The **ileocolic artery** branches from the superior mesenteric artery and supplies the terminal ileum, cecum, and appendix. While it provides blood supply to the appendix, it is not a direct or consistent surface landmark for locating the appendix itself, especially in complex cases with adhesions.
- Locating the artery would be more complex and less reliable for initial identification compared to the teniae coli.
Abdominal radiologic landmarks US Medical PG Question 10: A 72-year-old male presents to a cardiac surgeon for evaluation of severe aortic stenosis. He has experienced worsening dyspnea with exertion over the past year. The patient also has a history of poorly controlled hypertension, diabetes mellitus, and hyperlipidemia. An echocardiogram revealed a thickened calcified aortic valve. The surgeon is worried that the patient will be a poor candidate for open heart surgery and decides to perform a less invasive transcatheter aortic valve replacement. In order to perform this procedure, the surgeon must first identify the femoral pulse just inferior to the inguinal ligament and insert a catheter into the vessel in order to gain access to the arterial system. Which of the following structures is immediately lateral to this structure?
- A. Lymphatic vessels
- B. Femoral vein
- C. Sartorius muscle
- D. Pectineus muscle
- E. Femoral nerve (Correct Answer)
Abdominal radiologic landmarks Explanation: ***Femoral nerve***
- The **femoral nerve** lies lateral to the **femoral artery** within the **femoral triangle**.
- The order of structures from **lateral to medial** under the inguinal ligament is remembered by the mnemonic **NAVEL**: **N**erve, **A**rtery, **V**ein, **E**mpty space, **L**ymphatics.
*Lymphatic vessels*
- **Lymphatic vessels** and nodes are located most medially within the femoral triangle, medial to the femoral vein.
- This position is not immediately lateral to the femoral artery.
*Femoral vein*
- The **femoral vein** is located immediately medial to the **femoral artery**.
- It would not be found immediately lateral to the femoral artery.
*Sartorius muscle*
- The **sartorius muscle** forms the lateral boundary of the **femoral triangle** but is not immediately adjacent and lateral to the femoral artery within the triangle itself.
- The femoral nerve is enclosed within the iliopsoas fascial compartment, which runs deep to the sartorius.
*Pectineus muscle*
- The **pectineus muscle** forms part of the floor of the **femoral triangle**, but it is deep to the neurovascular structures.
- It is not immediately lateral to the femoral artery.
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