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?
Q2
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?
Q3
During a thoracotomy procedure, a surgeon needs to access the posterior mediastinum. Which of the following structures forms the anterior boundary of the posterior mediastinum?
Q4
A 27-year-old man presents to the emergency department for altered mental status. The patient was found napping in a local market and brought to the hospital. The patient has a past medical history of polysubstance abuse and is homeless. His temperature is 104°F (40.0°C), blood pressure is 100/52 mmHg, pulse is 133/min, respirations are 25/min, and oxygen saturation is 99% on room air. Physical exam is notable for an altered man. Cardiopulmonary exam reveals a murmur over the left lower sternal border. A bedside ultrasound reveals a vegetation on the tricuspid valve. The patient is ultimately started on IV fluids, norepinephrine, vasopressin, vancomycin, and piperacillin-tazobactam. A central line is immediately placed in the internal jugular vein and the femoral vein secondary to poor IV access. Cardiothoracic surgery subsequently intervenes to remove the vegetation. While recovering in the ICU, days 3-5 are notable for an improvement in the patient’s symptoms. Two additional peripheral IVs are placed while in the ICU on day 5, and the femoral line is removed. On day 6, the patient's fever and hemodynamic status worsen. Though he is currently responding and not complaining of any symptoms including headache, photophobia, neck stiffness, or pain, he states he is feeling weak. Jolt accentuation of headache is negative and his abdominal exam is benign. A chest radiograph, urinalysis, and echocardiogram are unremarkable though the patient’s blood cultures are positive when drawn. Which of the following is the best next step in management?
Q5
A 60-year-old woman is rushed to the emergency room after falling on her right elbow while walking down the stairs. She cannot raise her right arm. Her vital signs are stable, and the physical examination reveals loss of sensation over the upper lateral aspect of the right arm and shoulder. A radiologic evaluation shows a fracture of the surgical neck of the right humerus. Which of the following muscles is supplied by the nerve that is most likely damaged?
Q6
A 68-year-old man comes to the physician because of a 4-month history of difficulty swallowing. During this time, he has also had a 7-kg (15-lb) weight loss. Esophagogastroduodenoscopy shows an exophytic mass in the distal third of the esophagus. Histological examination of a biopsy specimen shows a well-differentiated adenocarcinoma. The patient is scheduled for surgical resection of the tumor. During the procedure, the surgeon damages a structure that passes through the diaphragm along with the esophagus at the level of the tenth thoracic vertebra (T10). Which of the following structures was most likely damaged?
Q7
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?
Q8
An 18-year-old man is brought to the emergency department 30 minutes after being stabbed in the chest during a fight. He has no other injuries. His pulse is 120/min, blood pressure is 90/60 mm Hg, and respirations are 22/min. Examination shows a 4-cm deep, straight stab wound in the 4th intercostal space 2 cm medial to the right midclavicular line. The knife most likely passed through which of the following structures?
Q9
A 23-year-old man is brought to the emergency department by a coworker for an injury sustained at work. He works in construction and accidentally shot himself in the chest with a nail gun. Physical examination shows a bleeding wound in the left hemithorax at the level of the 4th intercostal space at the midclavicular line. Which of the following structures is most likely injured in this patient?
Q10
A 35-year-old man comes to the physician because of a 3-month history of intermittent right lateral hip pain that radiates to the thigh. Climbing stairs and lying on his right side aggravates the pain. Examination shows tenderness to palpation over the upper lateral part of the right thigh. There is no swelling. When the patient is asked to abduct the right leg against resistance, tenderness is noted. An x-ray of the pelvis shows no abnormalities. Which of the following structures is the most likely source of this patient's pain?
Surface anatomy for clinical procedures US Medical PG Practice Questions and MCQs
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
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.
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
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.
Question 3: During a thoracotomy procedure, a surgeon needs to access the posterior mediastinum. Which of the following structures forms the anterior boundary of the posterior mediastinum?
A. Descending thoracic aorta
B. Pericardial sac (Correct Answer)
C. Azygos vein
D. Thoracic vertebrae
E. Sternum
Explanation: ***Pericardial sac***
- The **pericardial sac** (and the diaphragm, inferiorly) forms the anterior boundary of the **posterior mediastinum** [1].
- This anatomical relationship is crucial for surgeons during thoracotomy to distinguish between the middle and posterior mediastinal compartments [1].
*Descending thoracic aorta*
- The **descending thoracic aorta** is a large vessel located *within* the posterior mediastinum itself, typically running along its left side [2].
- Therefore, it is a content of the posterior mediastinum, not a boundary.
*Azygos vein*
- The **azygos vein** is also a major structure *within* the posterior mediastinum, running along the right side of the vertebral column.
- It is a content, not a boundary, of this compartment.
*Thoracic vertebrae*
- The **thoracic vertebrae** form the *posterior* boundary of the posterior mediastinum [1].
- This anatomical landmark gives the posterior mediastinum its name and defines its dorsal limit.
Question 4: A 27-year-old man presents to the emergency department for altered mental status. The patient was found napping in a local market and brought to the hospital. The patient has a past medical history of polysubstance abuse and is homeless. His temperature is 104°F (40.0°C), blood pressure is 100/52 mmHg, pulse is 133/min, respirations are 25/min, and oxygen saturation is 99% on room air. Physical exam is notable for an altered man. Cardiopulmonary exam reveals a murmur over the left lower sternal border. A bedside ultrasound reveals a vegetation on the tricuspid valve. The patient is ultimately started on IV fluids, norepinephrine, vasopressin, vancomycin, and piperacillin-tazobactam. A central line is immediately placed in the internal jugular vein and the femoral vein secondary to poor IV access. Cardiothoracic surgery subsequently intervenes to remove the vegetation. While recovering in the ICU, days 3-5 are notable for an improvement in the patient’s symptoms. Two additional peripheral IVs are placed while in the ICU on day 5, and the femoral line is removed. On day 6, the patient's fever and hemodynamic status worsen. Though he is currently responding and not complaining of any symptoms including headache, photophobia, neck stiffness, or pain, he states he is feeling weak. Jolt accentuation of headache is negative and his abdominal exam is benign. A chest radiograph, urinalysis, and echocardiogram are unremarkable though the patient’s blood cultures are positive when drawn. Which of the following is the best next step in management?
A. Add micafungin to the patient’s antibiotics
B. Perform a lumbar puncture
C. Remove all peripheral IV’s and send for cultures
D. Add cefepime to the patient’s antibiotics
E. Remove the central line and send for cultures (Correct Answer)
Explanation: **Correct: Remove the central line and send for cultures**
- The patient's worsening fever and hemodynamic instability on day 6, despite initial improvement, raise suspicion for a **catheter-related bloodstream infection (CRBSI)**, especially given the history of central line placement.
- **Prompt removal of the catheter** and sending the tip for culture is crucial for diagnosis and treatment of potential CRBSI, as the source of infection often resides within the biofilm on the catheter.
*Incorrect: Remove all peripheral IV's and send for cultures*
- While **peripheral IVs** can be a source of infection, the central line was placed earlier and is associated with a much higher risk of serious infection, especially in a critically ill patient.
- The patient's initial improvement followed by deterioration points more towards a **central line-associated infection** rather than new peripheral IVs placed only on day 5.
*Incorrect: Perform a lumbar puncture*
- Although the patient has altered mental status, the absence of focal neurological deficits, headache, photophobia, and neck stiffness, along with a negative **Jolt accentuation of headache**, makes **meningitis** less likely as the primary cause of deterioration.
- The more immediate and likely cause of worsening sepsis in this context is a **catheter-related infection**.
*Incorrect: Add micafungin to the patient's antibiotics*
- Adding an antifungal agent such as **micafungin** would be considered if there was a strong suspicion of a fungal infection, which is not indicated by the current blood cultures or clinical picture.
- Empiric antifungal therapy is typically reserved for patients with persistent fever refractory to broad-spectrum antibiotics, known fungal exposure, or specific risk factors.
*Incorrect: Add cefepime to the patient's antibiotics*
- The patient is already on **vancomycin and piperacillin-tazobactam**, which provides broad-spectrum coverage for both gram-positive and gram-negative bacteria, including *Pseudomonas aeruginosa*.
- Adding **cefepime** would broaden gram-negative coverage further but is usually unnecessary unless the current regimen is failing due to specific resistant organisms, and the more likely source of infection should be addressed first.
Question 5: A 60-year-old woman is rushed to the emergency room after falling on her right elbow while walking down the stairs. She cannot raise her right arm. Her vital signs are stable, and the physical examination reveals loss of sensation over the upper lateral aspect of the right arm and shoulder. A radiologic evaluation shows a fracture of the surgical neck of the right humerus. Which of the following muscles is supplied by the nerve that is most likely damaged?
A. Teres minor (Correct Answer)
B. Teres major
C. Subscapularis
D. Infraspinatus
E. Supraspinatus
Explanation: ***Teres minor***
- A fracture of the **surgical neck of the humerus** often damages the **axillary nerve**, which innervates the **teres minor**.
- The axillary nerve also supplies the **deltoid muscle** and provides cutaneous sensation to the **upper lateral arm**, consistent with the patient's sensory loss.
*Teres major*
- This muscle is innervated by the **lower subscapular nerve**, which is less likely to be damaged in a surgical neck fracture.
- Its primary action is **adduction** and **internal rotation** of the arm.
*Subscapularis*
- The **subscapularis** is innervated by the **upper and lower subscapular nerves**.
- While it contributes to internal rotation, its nerve supply is typically protected in this type of fracture.
*Infraspinatus*
- The **infraspinatus** muscle is innervated by the **suprascapular nerve**.
- This nerve is generally not affected by a fracture of the surgical neck of the humerus.
*Supraspinatus*
- Similar to the infraspinatus, the **supraspinatus** is also innervated by the **suprascapular nerve**.
- Damage to this nerve due to a humeral surgical neck fracture is uncommon.
Question 6: A 68-year-old man comes to the physician because of a 4-month history of difficulty swallowing. During this time, he has also had a 7-kg (15-lb) weight loss. Esophagogastroduodenoscopy shows an exophytic mass in the distal third of the esophagus. Histological examination of a biopsy specimen shows a well-differentiated adenocarcinoma. The patient is scheduled for surgical resection of the tumor. During the procedure, the surgeon damages a structure that passes through the diaphragm along with the esophagus at the level of the tenth thoracic vertebra (T10). Which of the following structures was most likely damaged?
A. Azygos vein
B. Vagus nerve (Correct Answer)
C. Right phrenic nerve
D. Inferior vena cava
E. Thoracic duct
Explanation: ***Vagus nerve***
- The **esophagus** passes through the diaphragm at the level of the **T10 vertebra**, accompanied by the **anterior and posterior vagal trunks**. Damage to these nerves is a known complication of esophageal surgery.
- The vagus nerves provide **parasympathetic innervation** to the gastrointestinal tract, and their close proximity to the esophagus makes them vulnerable during tumor resection.
*Azygos vein*
- The **azygos vein** typically passes through the diaphragm at the level of **T12** through the **aortic hiatus**, not with the esophagus at T10.
- It drains into the superior vena cava and is located more posteriorly in the mediastinum.
*Right phrenic nerve*
- The **right phrenic nerve** passes through the diaphragm with the **inferior vena cava** at the level of **T8**, innervating the diaphragm.
- It is located more anteriorly and laterally to the esophagus, making direct damage during esophageal surgery less likely than the vagus nerves.
*Inferior vena cava*
- The **inferior vena cava (IVC)** passes through its own opening in the central tendon of the diaphragm at the level of **T8**, not with the esophagus at T10.
- Damage to the IVC would result in significant hemorrhage and is typically a separate surgical concern.
*Thoracic duct*
- The **thoracic duct** passes through the **aortic hiatus** at the level of **T12** along with the aorta, collecting lymph from most of the body.
- Its location makes it less likely to be damaged during a standard esophageal resection at T10 compared to the vagus nerves.
Question 7: 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)
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.
Question 8: An 18-year-old man is brought to the emergency department 30 minutes after being stabbed in the chest during a fight. He has no other injuries. His pulse is 120/min, blood pressure is 90/60 mm Hg, and respirations are 22/min. Examination shows a 4-cm deep, straight stab wound in the 4th intercostal space 2 cm medial to the right midclavicular line. The knife most likely passed through which of the following structures?
A. Serratus anterior muscle, pleura, inferior vena cava
B. External oblique muscle, superior epigastric artery, azygos vein
C. Pectoralis minor muscle, dome of the diaphragm, right lobe of the liver
D. Intercostal muscles, internal thoracic artery, right heart
E. Pectoral fascia, transversus thoracis muscle, right lung (Correct Answer)
Explanation: ***Pectoral fascia, transversus thoracis muscle, right lung***
* The stab wound is in the **4th intercostal space**, 2 cm medial to the right midclavicular line, placing it over the anterior chest wall. This trajectory would first penetrate the **pectoral fascia**.
* Deeper structures in this region include the **transversus thoracis muscle** and, given the depth, the **right lung** as it extends superiorly behind the anterior chest wall.
* *Serratus anterior muscle, pleura, inferior vena cava*
* The **serratus anterior muscle** is more laterally positioned, typically covering the side of the rib cage.
* The **inferior vena cava** is located more medially and posteriorly within the mediastinum, deep to the diaphragm, making it an unlikely target for an anterior 4th intercostal stab.
* *External oblique muscle, superior epigastric artery, azygos vein*
* The **external oblique muscle** is part of the abdominal wall and would not be penetrated in the 4th intercostal space.
* The **superior epigastric artery** is lower, typically extending into the abdominal wall, and the **azygos vein** is in the posterior mediastinum, not in the path of this superficial anterior stab wound.
* *Pectoralis minor muscle, dome of the diaphragm, right lobe of the liver*
* The **pectoralis minor muscle** is located deep to the pectoralis major, which would be penetrated. However, a stab at the 4th intercostal space would be too high to directly involve the **dome of the diaphragm** or the **right lobe of the liver**, which are typically below the 5th intercostal space, especially in forced expiration.
* *Intercostal muscles, internal thoracic artery, right heart*
* The **intercostal muscles** would certainly be traversed.
* However, the **internal thoracic artery** runs paramedially (about 1-2 cm from the sternum), and getting to the **right heart** would require a more medial and deeper trajectory, potentially causing immediate tamponade or severe hemorrhage.
Question 9: A 23-year-old man is brought to the emergency department by a coworker for an injury sustained at work. He works in construction and accidentally shot himself in the chest with a nail gun. Physical examination shows a bleeding wound in the left hemithorax at the level of the 4th intercostal space at the midclavicular line. Which of the following structures is most likely injured in this patient?
A. Right atrium of the heart
B. Inferior vena cava
C. Left upper lobe of the lung (Correct Answer)
D. Left atrium of the heart
E. Superior vena cava
Explanation: ***Left upper lobe of the lung***
- The **left upper lobe of the lung** extends to the 4th intercostal space at the midclavicular line, making it the most probable structure to be traversed by a penetrating injury at this location.
- The **pleural cavity** and lung tissue are superficially located in this region, making them highly susceptible to injury from a nail gun.
*Right atrium of the heart*
- The **right atrium** is located predominantly on the right side of the sternum, more centrally, and slightly to the right of the midclavicular line.
- An injury at the **left 4th intercostal space at the midclavicular line** would typically be too lateral and superior to directly injure the right atrium.
*Inferior vena cava*
- The **inferior vena cava (IVC)** enters the right atrium from below, primarily located within the abdomen and passing through the diaphragm at the level of T8.
- Its position is far too **inferior and posterior** relative to the 4th intercostal space to be directly injured by this wound.
*Left atrium of the heart*
- The **left atrium** is the most posterior chamber of the heart and is largely covered by the left ventricle.
- Although part of the heart is on the left, an injury at the **4th intercostal space, midclavicular line**, would likely impact the left ventricle or lung tissue before reaching the left atrium, which is located more posteriorly and medially.
*Superior vena cava*
- The **superior vena cava (SVC)** is located to the right of the midline, formed by the brachiocephalic veins behind the right first costal cartilage.
- Its position is too **medial and superior**, on the right side, to be directly injured by a nail penetrating the left 4th intercostal space at the midclavicular line.
Question 10: A 35-year-old man comes to the physician because of a 3-month history of intermittent right lateral hip pain that radiates to the thigh. Climbing stairs and lying on his right side aggravates the pain. Examination shows tenderness to palpation over the upper lateral part of the right thigh. There is no swelling. When the patient is asked to abduct the right leg against resistance, tenderness is noted. An x-ray of the pelvis shows no abnormalities. Which of the following structures is the most likely source of this patient's pain?
A. Femoral head
B. Greater trochanter (Correct Answer)
C. Iliotibial band
D. Acetabulum
E. Lateral femoral cutaneous nerve
Explanation: ***Greater trochanter***
- The patient's symptoms of **intermittent right lateral hip pain** radiating to the thigh, aggravated by climbing stairs and lying on the affected side, and tenderness over the **upper lateral part of the right thigh** are classic signs of **trochanteric bursitis**.
- Pain with **resisted abduction** further points to inflammation of the **gluteus medius** or its associated bursa at the greater trochanter.
*Femoral head*
- Pain originating from the **femoral head** typically presents as deep, generalized groin or hip joint pain, often exacerbated by weight-bearing activities, and may be associated with limited range of motion in multiple planes.
- An **x-ray showing no abnormalities** makes femoral head issues like avascular necrosis or significant arthritis less likely.
*Iliotibial band*
- **Iliotibial band (ITB) syndrome** usually causes pain along the **lateral aspect of the knee**, particularly in runners or cyclists, due to friction over the lateral femoral epicondyle.
- While the ITB traverses the lateral thigh, the primary point of tenderness and mechanism of pain in this case (tenderness over the upper lateral thigh, pain with resisted abduction) is not typical for ITB syndrome affecting the knee.
*Acetabulum*
- Pain from the **acetabulum** would generally be deep within the hip joint, similar to femoral head issues, and often accompanied by a **limited range of motion** or clicking/locking sensations, and would be associated with intra-articular pathology.
- An **unremarkable X-ray** and the specific finding of **tenderness over the lateral thigh** make acetabular pathology less likely.
*Lateral femoral cutaneous nerve*
- Entrapment of the **lateral femoral cutaneous nerve** (meralgia paresthetica) typically causes **numbness, burning, or tingling** on the anterolateral thigh, not primarily sharp, intermittent pain aggravated by movement and palpation in the manner described.
- While pain can be present, the absence of **paresthesias** and the mechanical nature of the pain (aggravated by resisted abduction) make nerve entrapment less probable.
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