Linear growth of bone is disturbed when a fracture occurs in which part?
Q2
A 14-year-old boy is brought to the physician for the evaluation of back pain for the past six months. The pain is worse with exercise and when reclining. He attends high school and is on the swim team. He also states that he lifts weights on a regular basis. He has not had any trauma to the back or any previous problems with his joints. He has no history of serious illness. His father has a disc herniation. Palpation of the spinous processes at the lumbosacral area shows that two adjacent vertebrae are displaced and are at different levels. Muscle strength is normal. Sensation to pinprick and light touch is intact throughout. When the patient is asked to walk, a waddling gait is noted. Passive raising of either the right or left leg causes pain radiating down the ipsilateral leg. Which of the following is the most likely diagnosis?
Q3
A 53-year-old man with a history of alcoholic liver cirrhosis was admitted to the hospital with ascites and general wasting. He has a history of 3-5 ounces of alcohol consumption per day for 20 years and 20-pack-year smoking history. Past medical history is significant for alcoholic cirrhosis of the liver, diagnosed 5 years ago. On physical examination, the abdomen is firm and distended. There is mild tenderness to palpation in the right upper quadrant with no rebound or guarding. Shifting dullness and a positive fluid wave is present. Prominent radiating umbilical varices are noted. Laboratory values are significant for the following:
Total bilirubin 4.0 mg/dL
Aspartate aminotransferase (AST) 40 U/L
Alanine aminotransferase (ALT) 18 U/L
Gamma-glutamyltransferase 735 U/L
Platelet count 11,000/mm3
WBC 4,300/mm3
Serology for viral hepatitis B and C are negative. A Doppler ultrasound of the abdomen shows significant enlargement of the epigastric superficial veins and hepatofugal flow within the portal vein. There is a large volume of ascites present. Paracentesis is performed in which 10 liters of straw-colored fluid is removed. Which of the following sites of the portocaval anastomosis is most likely to rupture and bleed first in this patient?
Q4
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?
Q5
A 65-year-old man presents to the emergency department with abdominal pain and a pulsatile abdominal mass. Further examination of the mass shows that it is an abdominal aortic aneurysm. A computed tomography scan with contrast reveals an incidental finding of a horseshoe kidney, and the surgeon is informed of this finding prior to operating on the aneurysm. Which of the following may complicate the surgical approach in this patient?
Q6
A 22-year-old Caucasian male is stabbed in his left flank, injuring his left kidney. As the surgeon undertakes operative repair, she reviews relevant renal anatomy. All of the following are correct regarding the left kidney EXCEPT?
Q7
A 21-year-old man was involved in a motor vehicle accident and died. At autopsy, the patient demonstrated abnormally increased mobility at the neck. A section of cervical spinal cord at C6 was removed and processed into slides. Which of the following gross anatomic features is most likely true of this spinal cord level?
Q8
A 65-year-old woman with osteoarthritis comes to the physician because of severe lower back and left leg pain. She has chronic lower back pain that is usually well-controlled with ibuprofen, but 3 hours ago her back pain acutely worsened after she picked up her 3-year-old granddaughter. The pain radiates from her lower back over her left outer thigh and knee towards the top of her big toe. Physical examination shows a diminished Achilles reflex on the left side. Muscle strength is 5/5 in all extremities and there are no sensory deficits. Steroid injection into which of the following anatomical locations is most likely to relieve her symptoms?
Q9
A 17-year-old boy is brought to the pediatrician by his mother for fatigue. The patient reports that he was supposed to try out for winter track this year, but he had to quit because his “legs just give up.” He also reports increased difficulty breathing with exercise but denies chest pain or palpitations. He has no chronic medical conditions and takes no medications. He has had no surgeries in the past. The mother reports that he met all his pediatric milestones and is an “average” student. He is up-to-date on all childhood vaccinations, including a recent flu vaccine. On physical examination, there is mild lumbar lordosis. The patient’s thighs appear thin in diameter compared to his lower leg muscles, and he walks on his toes. An electrocardiogram shows 1st degree atrioventricular nodal block. Which of the following is the most likely cause of the patient’s condition?
Q10
A 17-year-old boy is brought to the emergency department by his parents because of crushing chest pain, nausea, and vomiting for the past 2 hours. The pain is constant and radiates to his left shoulder. Over the past year, he has been admitted to the hospital twice for deep vein thrombosis. He has a history of learning disability and has been held back three grades. The patient is at the 99th percentile for length and the 45th percentile for weight. His pulse is 110/min, respirations are 21/min, and blood pressure is 128/84 mm Hg. His fingers are long and slender, and his arm span exceeds his body height. Electrocardiography shows ST-segment elevation in leads V1 and V2. His serum troponin I concentration is 2.0 ng/mL (N ≤ 0.04). Coronary angiography shows 90% occlusion of the proximal left anterior descending artery. Further evaluation of this patient is most likely to show which of the following findings?
Gross Anatomy US Medical PG Practice Questions and MCQs
Question 1: Linear growth of bone is disturbed when a fracture occurs in which part?
A. Epiphysis
B. Diaphysis
C. Metaphysis
D. Epiphyseal plate (Correct Answer)
E. Periosteum
Explanation: ***Epiphyseal plate***
- The **epiphyseal plate**, also known as the **growth plate**, is a cartilaginous disc responsible for the **longitudinal growth** of long bones.
- A fracture in this region can damage the **chondrocytes** and disrupt the normal process of endochondral ossification, leading to **growth arrest** or limb length discrepancy.
*Epiphysis*
- The **epiphysis** is the end part of a long bone, often covered by **articular cartilage**, forming a joint.
- While an epiphyseal fracture can affect joint function, it typically does not directly disturb the **linear growth** of the bone unless it extends into the growth plate.
*Diaphysis*
- The **diaphysis** is the main or midsection of a long bone, composed primarily of **compact bone**.
- Fractures in the diaphysis generally heal through **callus formation** and remodeling, usually without significantly impacting the overall **linear growth** of the bone.
*Metaphysis*
- The **metaphysis** is the wider portion of a long bone, adjacent to the growth plate and diaphysis.
- Though highly vascular, fractures to the metaphysis usually heal well and do not directly control **linear bone growth** like the epiphyseal plate.
*Periosteum*
- The **periosteum** is the fibrous membrane covering the outer surface of bones, important for **appositional growth** (bone widening) and fracture healing.
- While it contains osteogenic cells that contribute to bone repair and thickness, it does not control **longitudinal bone growth**, which is the function of the epiphyseal plate.
Question 2: A 14-year-old boy is brought to the physician for the evaluation of back pain for the past six months. The pain is worse with exercise and when reclining. He attends high school and is on the swim team. He also states that he lifts weights on a regular basis. He has not had any trauma to the back or any previous problems with his joints. He has no history of serious illness. His father has a disc herniation. Palpation of the spinous processes at the lumbosacral area shows that two adjacent vertebrae are displaced and are at different levels. Muscle strength is normal. Sensation to pinprick and light touch is intact throughout. When the patient is asked to walk, a waddling gait is noted. Passive raising of either the right or left leg causes pain radiating down the ipsilateral leg. Which of the following is the most likely diagnosis?
A. Spondylolisthesis (Correct Answer)
B. Overuse injury
C. Ankylosing spondylitis
D. Disc herniation
E. Facet joint syndrome
Explanation: ***Spondylolisthesis***
- The patient presents with **back pain worse with exercise and reclining**, along with **palpable displacement of adjacent vertebrae** at different levels, which are classic signs of spondylolisthesis. The **waddling gait** and pain radiating down the leg upon passive leg raising (suggesting nerve root irritation) further support this diagnosis.
- Spondylolisthesis, particularly **isthmic type**, is common in adolescent athletes involved in sports like swimming and weightlifting due to repetitive hyperextension leading to stress fractures in the pars interarticularis.
*Overuse injury*
- While overuse injuries are common in athletes, they typically present with generalized pain or tenderness in the affected area without distinct **vertebral displacement** or neurological signs like radiating pain and a waddling gait.
- The specific signs of palpable vertebral displacement and nerve root irritation point to a more severe structural issue than a simple overuse soft tissue injury.
*Ankylosing spondylitis*
- **Ankylosing spondylitis** usually presents with **inflammatory back pain** that improves with exercise, not worsens, and often affects young adults, not typically a 14-year-old with these specific physical findings.
- It would not explain the **palpable vertebral displacement** or the sudden onset of neurological symptoms like radiating leg pain and waddling gait.
*Disc herniation*
- While disc herniation can cause **radiating leg pain** and back pain, it typically doesn't present with **palpable vertebral displacement** or a waddling gait in an adolescent without a history of significant trauma.
- The physical exam finding of displaced vertebrae is more indicative of a structural instability like spondylolisthesis rather than an isolated disc problem, even though a father has a history.
*Facet joint syndrome*
- Facet joint syndrome usually results in localized back pain that **worsens with extension and rotation** but typically does not cause **palpable vertebral displacement** or neurological deficits like radiating pain and a waddling gait.
- It is also more common in older adults due to degenerative changes, rather than a 14-year-old athlete.
Question 3: A 53-year-old man with a history of alcoholic liver cirrhosis was admitted to the hospital with ascites and general wasting. He has a history of 3-5 ounces of alcohol consumption per day for 20 years and 20-pack-year smoking history. Past medical history is significant for alcoholic cirrhosis of the liver, diagnosed 5 years ago. On physical examination, the abdomen is firm and distended. There is mild tenderness to palpation in the right upper quadrant with no rebound or guarding. Shifting dullness and a positive fluid wave is present. Prominent radiating umbilical varices are noted. Laboratory values are significant for the following:
Total bilirubin 4.0 mg/dL
Aspartate aminotransferase (AST) 40 U/L
Alanine aminotransferase (ALT) 18 U/L
Gamma-glutamyltransferase 735 U/L
Platelet count 11,000/mm3
WBC 4,300/mm3
Serology for viral hepatitis B and C are negative. A Doppler ultrasound of the abdomen shows significant enlargement of the epigastric superficial veins and hepatofugal flow within the portal vein. There is a large volume of ascites present. Paracentesis is performed in which 10 liters of straw-colored fluid is removed. Which of the following sites of the portocaval anastomosis is most likely to rupture and bleed first in this patient?
A. Superior and middle rectal vein – inferior rectal veins
B. Umbilical vein – superficial epigastric veins
C. Esophageal branch of left gastric vein – esophageal branches of azygos vein (Correct Answer)
D. Paraumbilical veins – inferior epigastric veins
E. Short gastric veins – intercostal veins
Explanation: ***Esophageal branch of left gastric vein – esophageal branches of azygos vein***
- The gastroesophageal junction is the most frequent site of **life-threatening variceal bleeding** in patients with portal hypertension due to liver cirrhosis. The elevated portal pressure forces blood from the **left gastric (coronary) vein** into the thinner-walled esophageal veins which drain into the azygos system.
- The patient's history of **alcoholic liver cirrhosis** makes portal hypertension and subsequent esophageal varices highly likely. While other portocaval anastomoses exist, esophageal varices are clinically the most significant due to their propensity for rupture and severe hemorrhage.
*Superior and middle rectal vein – inferior rectal veins*
- This anastomosis concerns the rectums, involving the **superior rectal vein (portal system)** and the **middle/inferior rectal veins (systemic system)**.
- While portal hypertension can lead to **anorectal varices**, also known as hemorrhoids, these are less prone to life-threatening hemorrhage compared to esophageal varices and typically present with bleeding on defecation or discomfort.
*Umbilical vein – superficial epigastric veins*
- This anastomosis is responsible for the formation of a **caput medusae**, which is a sign of portal hypertension where prominent periumbilical veins radiate from the navel. The patient presents with prominent "radiating umbilical varices," which is consistent with this finding.
- While visually striking and indicative of portal hypertension, these superficial varices are generally **not associated with significant or life-threatening hemorrhage** compared to esophageal varices.
*Paraumbilical veins – inferior epigastric veins*
- The paraumbilical veins run within the falciform ligament and connect the portal system to the systemic circulation via the **epigastric veins**.
- This anastomosis contributes to the formation of caput medusae but is **not a common site for clinically significant bleeding** requiring intervention compared to esophageal varices.
*Short gastric veins – intercostal veins*
- The short gastric veins drain into the splenic vein (part of the portal system) and connect to systemic veins such as the intercostal veins via retroperitoneal anastomoses.
- While this is a potential site of portosystemic shunting, the short gastric veins are more commonly implicated in **gastric varices**, particularly in the fundus. However, gastric varices are less frequent and **rupture less commonly than esophageal varices**, although hemorrhage from them can be more severe when it does occur.
Question 4: 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 5: A 65-year-old man presents to the emergency department with abdominal pain and a pulsatile abdominal mass. Further examination of the mass shows that it is an abdominal aortic aneurysm. A computed tomography scan with contrast reveals an incidental finding of a horseshoe kidney, and the surgeon is informed of this finding prior to operating on the aneurysm. Which of the following may complicate the surgical approach in this patient?
A. Anomalous origins of multiple renal arteries (Correct Answer)
B. Low glomerular filtration rate due to unilateral renal agenesis
C. Proximity of the fused kidney to the celiac artery
D. Abnormal relationship between the kidney and the superior mesenteric artery
E. There are no additional complications
Explanation: ***Anomalous origins of multiple renal arteries***
- A horseshoe kidney often receives its blood supply from **multiple renal arteries** arising anomalously from the aorta, iliac arteries, or inferior mesenteric artery.
- These aberrant vessels can cross the surgical field and complicate **abdominal aortic aneurysm repair**, increasing the risk of injury and hemorrhage.
*Low glomerular filtration rate due to unilateral renal agenesis*
- This patient has a **horseshoe kidney**, which involves fused kidneys, not renal agenesis (absence of a kidney).
- While chronic kidney disease can be associated with horseshoe kidneys, **unilateral agenesis** is a distinct condition and not described in this scenario.
*Proximity of the fused kidney to the celiac artery*
- The fused portion of a horseshoe kidney (the **isthmus**) typically lies anterior to the great vessels at the L3-L5 vertebral level, below the origin of the celiac artery.
- Therefore, its proximity to the **celiac artery** is generally not the primary surgical concern during abdominal aortic aneurysm repair.
*Abnormal relationship between the kidney and the superior mesenteric artery*
- The superior mesenteric artery typically originates from the aorta above the level of the horseshoe kidney's isthmus.
- While other anomalies can exist, an **abnormal relationship** between the kidney and the superior mesenteric artery is not a classic or primary complication of horseshoe kidney during AAA repair.
*There are no additional complications*
- The presence of a horseshoe kidney significantly increases the complexity of **abdominal aortic aneurysm** surgery.
- The potential for **vascular anomalies** and altered anatomical relationships makes this statement incorrect, as there are definite additional surgical considerations.
Question 6: A 22-year-old Caucasian male is stabbed in his left flank, injuring his left kidney. As the surgeon undertakes operative repair, she reviews relevant renal anatomy. All of the following are correct regarding the left kidney EXCEPT?
A. The left kidney has a longer renal vein than the right kidney
B. The left kidney underlies the left 12th rib
C. The left kidney moves vertically during deep breathing
D. The left kidney has a longer renal artery than the right kidney (Correct Answer)
E. The left kidney lies between T12 and L3
Explanation: ***The left kidney has a longer renal artery than the right kidney***
- The **aorta** lies to the left of the midline, so the **right renal artery** must traverse a greater distance to reach the right kidney.
- Therefore, the right renal artery is longer than the left renal artery.
*The left kidney has a longer renal vein than the right kidney*
- The **inferior vena cava (IVC)** is positioned to the right of the midline, requiring the **left renal vein** to cross the aorta to drain.
- This anatomical arrangement makes the left renal vein longer than the right renal vein.
*The left kidney underlies the left 12th rib*
- The kidneys are retroperitoneal organs, and the 12th rib provides significant posterior protection for **both kidneys**.
- The superior pole of the left kidney typically extends to the level of the **11th and 12th ribs**.
*The left kidney moves vertically during deep breathing*
- The kidneys are surrounded by **perirenal fat** and are influenced by the diaphragm's movement.
- During **deep inspiration**, the diaphragm descends, causing both kidneys to move vertically by 2-3 cm.
*The left kidney lies between T12 and L3*
- The kidneys are situated in the retroperitoneum, generally extending from the level of the **T12 vertebra** to the **L3 vertebra**.
- The left kidney is typically positioned slightly higher than the right kidney.
Question 7: A 21-year-old man was involved in a motor vehicle accident and died. At autopsy, the patient demonstrated abnormally increased mobility at the neck. A section of cervical spinal cord at C6 was removed and processed into slides. Which of the following gross anatomic features is most likely true of this spinal cord level?
A. Cuneate and gracilis fasciculi are present (Correct Answer)
B. Least amount of white matter
C. Prominent lateral horns
D. Absence of gray matter enlargement
E. Involvement with parasympathetic nervous system
Explanation: **Cuneate and gracilis fasciculi are present**
- At the **C6 level** of the spinal cord, both the **fasciculus gracilis** (carrying information from the lower body) and the **fasciculus cuneatus** (carrying information from the upper body) are present in the dorsal column.
- The fasciculus cuneatus typically appears at **T6 and above**, making it visible at C6.
*Least amount of white matter*
- The cervical spinal cord, particularly at C6, contains a **significant amount of white matter** because it carries all ascending and descending tracts to and from the brain, including those for the upper and lower limbs.
- The **sacral segments** typically have the least amount of white matter due to fewer tracts remaining.
*Prominent lateral horns*
- **Lateral horns** are characteristic of the **thoracic and upper lumbar (T1-L2/L3)** spinal cord segments, where they house preganglionic sympathetic neurons.
- They are generally **absent or poorly developed** in the cervical spinal cord.
*Absence of gray matter enlargement*
- The **cervical enlargement** of the spinal cord, particularly pronounced from C4 to T1, contains an increased amount of gray matter to accommodate the innervation of the **upper limbs**.
- Therefore, the C6 level would show **significant gray matter enlargement**.
*Involvement with parasympathetic nervous system*
- The **parasympathetic nervous system** exits the spinal cord at the **sacral levels (S2-S4)** and as cranial nerves, not primarily from the cervical spinal cord through distinct horns.
- The cervical spinal cord is primarily associated with **somatic motor and sensory pathways** for the neck, shoulders, and upper limbs, and receives some sympathetic input, but is not where parasympathetic outflow predominantly originates.
Question 8: A 65-year-old woman with osteoarthritis comes to the physician because of severe lower back and left leg pain. She has chronic lower back pain that is usually well-controlled with ibuprofen, but 3 hours ago her back pain acutely worsened after she picked up her 3-year-old granddaughter. The pain radiates from her lower back over her left outer thigh and knee towards the top of her big toe. Physical examination shows a diminished Achilles reflex on the left side. Muscle strength is 5/5 in all extremities and there are no sensory deficits. Steroid injection into which of the following anatomical locations is most likely to relieve her symptoms?
A. Subarachnoid space
B. Inferior facet joint
C. Intervertebral disc
D. Intervertebral foramen (Correct Answer)
E. Subdural space
Explanation: ***Intervertebral foramen***
- The patient's symptoms, including **radiating lower back and left leg pain** with a diminished **posterior tibial reflex**, are classic for **radiculopathy** due to **spinal nerve root compression**.
- Steroid injection into the intervertebral foramen, where the **nerve root exits the spinal canal**, is directly targeting the site of inflammation and compression, thus being most likely to relieve symptoms.
*Subarachnoid space*
- An injection into the **subarachnoid space** (intrathecal injection) is typically used for **spinal anesthesia** or to administer medications for widespread CNS conditions, not focal nerve root compression.
- While it contains CSF and nerve roots, it is not the most precise or appropriate location for an injection aimed at isolated radicular pain.
*Inferior facet joint*
- The **facet joints** are involved in **axial back pain**, usually worse with extension, and do not typically cause radicular symptoms radiating down the leg to the big toe with a specific dermatomal and myotomal distribution like L5 or S1.
- An injection here would target facet joint arthritis, which presents differently from the described radiculopathy.
*Intervertebral disc*
- An injection into the **intervertebral disc** (discography or disc annuloplasty) is generally a diagnostic procedure to identify pain originating from the disc or a treatment for discogenic pain, which is usually axial and not radicular.
- Injecting steroids directly into the disc is not a standard treatment for nerve root compression.
*Subdural space*
- The **subdural space** is a potential space between the dura mater and arachnoid mater; injections into this space are rarely performed therapeutically and carry significant risks without clear benefit for radiculopathy.
- An inadvertent subdural injection during an epidural procedure can lead to complications such as a **subdural hematoma** or paralysis.
Question 9: A 17-year-old boy is brought to the pediatrician by his mother for fatigue. The patient reports that he was supposed to try out for winter track this year, but he had to quit because his “legs just give up.” He also reports increased difficulty breathing with exercise but denies chest pain or palpitations. He has no chronic medical conditions and takes no medications. He has had no surgeries in the past. The mother reports that he met all his pediatric milestones and is an “average” student. He is up-to-date on all childhood vaccinations, including a recent flu vaccine. On physical examination, there is mild lumbar lordosis. The patient’s thighs appear thin in diameter compared to his lower leg muscles, and he walks on his toes. An electrocardiogram shows 1st degree atrioventricular nodal block. Which of the following is the most likely cause of the patient’s condition?
A. Absent dystrophin
B. Trinucleotide repeats
C. Abnormal dystrophin (Correct Answer)
D. Sarcomere protein dysfunction
E. Peripheral nerve demyelination
Explanation: ***Abnormal dystrophin***
* The patient's presentation with **fatigue**, exercise intolerance, muscular weakness ("legs just give up"), **lumbar lordosis**, **calf pseudohypertrophy** (thighs thin compared to lower legs), and **toe walking** are classic signs of **Becker muscular dystrophy (BMD)**.
* BMD is caused by mutations in the *DMD* gene leading to **abnormally sized or reduced, but still functional, dystrophin protein**. This allows for a milder, later-onset phenotype compared to Duchenne muscular dystrophy.
*Absent dystrophin*
* **Absent dystrophin** is characteristic of **Duchenne muscular dystrophy (DMD)**, which typically presents earlier in childhood with more severe and rapid progression of muscle weakness.
* While both BMD and DMD are X-linked dystrophinopathies, the patient's age (17 years) and milder symptoms are more consistent with the later onset and slower progression seen in BMD.
*Trinucleotide repeats*
* **Trinucleotide repeat disorders** like **myotonic dystrophy** or **Friedreich's ataxia** can cause muscle weakness and cardiac issues but have different clinical presentations.
* Myotonic dystrophy often involves **myotonia** (delayed muscle relaxation), frontal balding, and cataracts, which are not described here.
*Sarcomere protein dysfunction*
* **Sarcomere protein dysfunction** is primarily associated with various forms of **cardiomyopathy** (e.g., hypertrophic cardiomyopathy), which would explain the cardiac findings, but it does not typically cause the specific pattern of limb girdle weakness, calf pseudohypertrophy, and toe walking seen in this patient.
* Conditions like hereditary myopathies can involve sarcomeric proteins, but the overall clinical picture strongly points to a dystrophinopathy.
*Peripheral nerve demyelination*
* **Peripheral nerve demyelination** is characteristic of conditions like **Charcot-Marie-Tooth disease** (CMT), which affects peripheral nerves and causes distal muscle weakness and atrophy, foot deformities (e.g., pes cavus), and sensory loss.
* While CMT can cause toe walking, it typically involves significant distal muscle wasting rather than calf pseudohypertrophy, and the cardiac involvement (1st-degree AV block) is less commonly a prominent feature compared to muscular dystrophies.
Question 10: A 17-year-old boy is brought to the emergency department by his parents because of crushing chest pain, nausea, and vomiting for the past 2 hours. The pain is constant and radiates to his left shoulder. Over the past year, he has been admitted to the hospital twice for deep vein thrombosis. He has a history of learning disability and has been held back three grades. The patient is at the 99th percentile for length and the 45th percentile for weight. His pulse is 110/min, respirations are 21/min, and blood pressure is 128/84 mm Hg. His fingers are long and slender, and his arm span exceeds his body height. Electrocardiography shows ST-segment elevation in leads V1 and V2. His serum troponin I concentration is 2.0 ng/mL (N ≤ 0.04). Coronary angiography shows 90% occlusion of the proximal left anterior descending artery. Further evaluation of this patient is most likely to show which of the following findings?
A. Macroorchidism
B. Bilateral gynecomastia
C. Ascending aortic aneurysm
D. Saccular cerebral aneurysms
E. Downward lens subluxation (Correct Answer)
Explanation: ***Downward lens subluxation***
- This patient's presentation is classic for **homocystinuria**, a metabolic disorder caused by **cystathionine β-synthase deficiency**.
- Key diagnostic features include: **marfanoid habitus** (tall stature, arachnodactyly, arm span > height), **thromboembolic events** (recurrent DVTs and MI at young age), **intellectual disability** (learning disability, held back 3 grades), and **downward and inward lens subluxation (ectopia lentis)**.
- The **recurrent thromboembolism** (2 DVTs in past year + MI at age 17) is the most distinctive feature that differentiates homocystinuria from Marfan syndrome. Elevated homocysteine causes endothelial damage and platelet activation, leading to arterial and venous thrombosis.
- **Downward lens subluxation** is pathognomonic for homocystinuria (vs upward/temporal in Marfan syndrome).
*Macroorchidism*
- **Macroorchidism** (enlarged testes) is characteristic of **fragile X syndrome**, the most common inherited cause of intellectual disability.
- While this patient has learning disability, the **marfanoid habitus** and **thromboembolic events** are not features of fragile X syndrome.
*Ascending aortic aneurysm*
- **Ascending aortic aneurysm** is the classic cardiovascular complication of **Marfan syndrome**, a fibrillin-1 defect.
- While this patient has marfanoid features, **Marfan syndrome does NOT cause thromboembolism or intellectual disability**, which are the key distinguishing features in this case.
- Homocystinuria can mimic Marfan syndrome but is differentiated by thrombosis, mental retardation, and downward (not upward) lens dislocation.
*Saccular cerebral aneurysms*
- **Saccular (berry) aneurysms** are associated with **autosomal dominant polycystic kidney disease** and **Ehlers-Danlos syndrome type IV**.
- Neither condition fits this patient's presentation with marfanoid habitus, thromboembolism, and intellectual disability.
*Bilateral gynecomastia*
- **Bilateral gynecomastia** is seen in **Klinefelter syndrome** (47,XXY), which presents with tall stature, learning difficulties, and **hypogonadism with small, firm testes**.
- The marfanoid features (arachnodactyly, increased arm span) and thromboembolic events are not consistent with Klinefelter syndrome.
Question 11: A morbidly obese 43-year-old man presents for elective bariatric surgery after previously failing several non-surgical weight loss plans. After discussing the risks and benefits of several different procedures, a sleeve gastrectomy is performed. During the surgery, the surgeon begins by incising into the right half of the greater curvature of the stomach. Which of the following arteries most likely directly provides the blood supply to this region of the stomach?
A. Short gastric arteries
B. Right gastric artery
C. Right gastroduodenal artery
D. Right gastroepiploic artery (Correct Answer)
E. Splenic artery
Explanation: ***Right gastroepiploic artery***
- The **right gastroepiploic artery** (also known as the **right gastroomental artery**) is a branch of the **gastroduodenal artery** that runs along the **greater curvature of the stomach** from right to left.
- This artery is the primary blood supply to the **right portion of the greater curvature**, which corresponds to the region where an incision into the right half of the greater curvature would be made during a sleeve gastrectomy.
- It anastomoses with the left gastroepiploic artery along the greater curvature.
*Short gastric arteries*
- The **short gastric arteries** supply the **fundus** and a small portion of the superior body of the stomach, specifically to the left of the midline.
- They originate from the **splenic artery** and supply the left superior portion of the greater curvature, not the right half described in the question.
*Right gastric artery*
- The **right gastric artery** primarily supplies the **pyloric part of the stomach** and a portion of the **lesser curvature**.
- It arises from the **hepatic artery proper** and is not the main supply to the greater curvature.
*Right gastroduodenal artery*
- The **gastroduodenal artery** supplies the **duodenum** and the **head of the pancreas**.
- This artery is located inferior to the stomach and gives rise to the right gastroepiploic artery but does not directly supply the greater curvature itself.
*Splenic artery*
- The **splenic artery** is a large artery that primarily supplies the **spleen** and gives off branches like the **short gastric arteries** and the **left gastroepiploic artery**.
- While it contributes indirectly via its branches to the left portion of the greater curvature, it does not directly supply the right half of the greater curvature.
Question 12: 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)
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.
Question 13: A 49-year-old man comes to the physician because of severe, shooting pain in his lower back for the past 2 weeks. The pain radiates down the back of both legs and started after he lifted a concrete manhole cover from the ground. Physical examination shows decreased sensation to light touch bilaterally over the lateral thigh area and lateral calf bilaterally. Patellar reflex is decreased on both sides. The passive raising of either the right or left leg beyond 30 degrees triggers a shooting pain down the leg past the knee. Which of the following is the most likely underlying cause of this patient's current condition?
A. Inflammatory reaction in the epidural space
B. Involuntary contraction of the paraspinal muscles
C. Compromised integrity of the vertebral body
D. Inflammatory degeneration of the spine
E. Herniation of nucleus pulposus into vertebral canal (Correct Answer)
Explanation: ***Herniation of nucleus pulposus into vertebral canal***
- The sudden onset of **bilateral lower back pain** radiating down both legs, associated with **lifting a heavy object**, and presenting with **decreased sensation** in dermatomal patterns (lateral thigh/calf) and **diminished patellar reflexes**, is highly consistent with **acute disc herniation**.
- **Positive straight leg raise test** (pain beyond 30 degrees) further implicates **nerve root compression** due to a herniated disc, specifically affecting the L3/L4 or L4/L5 levels given the reflex and sensory findings.
*Inflammatory reaction in the epidural space*
- While an inflammatory reaction can cause pain, it typically wouldn't present with such specific **neurological deficits** (sensory loss, reflex changes) and **mechanical provocation** (lifting, straight leg raise).
- This option does not explain the **radicular symptoms** so precisely or the classic presentation after acute strain.
*Involuntary contraction of the paraspinal muscles*
- **Muscle spasms** can cause severe back pain but usually do not lead to **bilateral radicular pain**, specific **sensory deficits**, or **reflex changes**.
- The symptoms described point to **nerve root impingement**, not just muscular pain.
*Compromised integrity of the vertebral body*
- Conditions like **vertebral fractures** or **tumors** affecting vertebral body integrity might cause severe localized pain, but wouldn't typically manifest as **bilateral radiculopathy** with specific **neurological deficits** and a clear mechanical trigger in this manner.
- While possible, it's not the most likely cause given the classic disc herniation presentation.
*Inflammatory degeneration of the spine*
- **Inflammatory degeneration** (e.g., degenerative disc disease, spondylosis) tends to have a more **chronic, progressive course** rather than the acute onset described after a specific event.
- While degeneration can predispose to herniation, it is not the immediate cause of the acute clinical picture of nerve impingement.
