A 35-year-old man is brought to the emergency department after a motorcycle accident. He is conscious but has pain in his chest. His vital signs are as follows: BP 100/60 mm Hg, pulse 120 bpm, and respiratory rate 22 breaths/min. Physical examination reveals bruising and tenderness over the left side of his chest. Which of the following is the most likely cause of his pain?

Correct Answer: A

Rationale: The correct answer is A: Rib fracture. Rationale: 1. The patient's presentation with chest pain, tenderness, and bruising after a motorcycle accident is highly suggestive of a traumatic injury like a rib fracture. 2. Rib fractures are common in blunt chest trauma and can cause significant pain with breathing and movement. 3. Tenderness over the affected area and pain on palpation are typical findings in rib fractures. 4. The vital signs of a stable blood pressure and tachycardia are consistent with a rib fracture without significant hemodynamic instability. Summary of incorrect choices: B: Pneumothorax - Less likely in this case as there is no mention of decreased breath sounds or respiratory distress. C: Pericarditis - Unlikely given the acute presentation after trauma and absence of classic pericarditis symptoms. D: Myocardial infarction - Not likely in a young patient with trauma and no risk factors for heart disease.

Correct Answer: B

Rationale: The most likely diagnosis for a 40-year-old woman presenting with ptosis, fatigue, and weakness of proximal upper limb muscles is myasthenia gravis (B). Myasthenia gravis is an autoimmune disorder characterized by muscle weakness that worsens with activity and improves with rest. Ptosis and proximal muscle weakness are classic features of myasthenia gravis due to antibodies targeting the acetylcholine receptors at the neuromuscular junction, leading to impaired muscle contraction. Multiple sclerosis (A) presents with neurological symptoms such as sensory deficits, vision changes, and coordination issues. Guillain-Barré syndrome (C) manifests as ascending muscle weakness and can have autonomic involvement. Lambert-Eaton syndrome (D) is characterized by muscle weakness that improves with activity, the opposite of myasthenia gravis.

Correct Answer: C

Rationale: The most likely diagnosis is C: Cirrhosis. This is supported by the patient's history of alcohol use, jaundice, elevated bilirubin and liver enzymes, abdominal pain, and ascites. Cirrhosis is a chronic liver disease often caused by excessive alcohol consumption, leading to liver damage and dysfunction. The other choices are less likely as chronic pancreatitis typically presents with pancreatic enzyme abnormalities, hepatitis presents with viral infection symptoms, and cholecystitis presents with gallbladder inflammation symptoms.

Correct Answer: B

Rationale: The high-pitched, tinkling bowel sounds indicate hyperperistalsis in response to bowel obstruction, leading to air and fluid passing through the narrowed area. This finding is consistent with option B, gastrointestinal obstruction. Normal peristalsis (option A) would present with regular, rhythmic bowel sounds. Gastroesophageal reflux disease (option C) is unrelated to bowel sounds and presents with heartburn and regurgitation. Diverticulitis (option D) typically presents with localized tenderness and pain in the lower left abdomen, not high-pitched bowel sounds. Therefore, the correct answer is B due to the characteristic bowel sound associated with gastrointestinal obstruction.

Correct Answer: D

Rationale: The correct answer is D: Cranial nerve XII (hypoglossal nerve). When the nurse asks the patient to stick out their tongue, they are testing the function of the hypoglossal nerve, which innervates the muscles responsible for tongue movement. Cranial nerve X (vagus nerve) is responsible for various functions such as swallowing and speech. Cranial nerve VII (facial nerve) controls facial expressions. Cranial nerve IX (glossopharyngeal nerve) is involved in taste sensation and swallowing. Therefore, the hypoglossal nerve is specifically responsible for tongue movement, making it the correct answer in this context.