A 62-year-old man comes to the physician for the evaluation of lower back pain and tingling and numbness in his legs for the past 6 months. The pain radiates bilaterally to his buttocks and legs and gets worse while standing or walking downhill. Two weeks ago, he had an upper respiratory tract infection that resolved spontaneously. He has hypertension and hypercholesterolemia. His son has ankylosing spondylitis. BMI is 27.8 kg/m2. There is no tenderness to palpation over the lumbar spine. Sensation to pinprick and light touch is decreased over the lower extremities. The patient's gait is unsteady and wide based. Muscle strength is normal. Deep tendon reflexes are 1+ bilaterally. Babinski's sign is absent bilaterally. Further evaluation is most likely to reveal which of the following findings?

A 59-year-old man comes to the physician for evaluation of a progressively enlarging, 8-mm skin lesion on the right shoulder that developed 1 month ago. The patient has a light-skinned complexion and has had several dysplastic nevi removed in the past. A photograph of the lesion is shown. The lesion is most likely derived from cells that are also the embryological origin of which of the following tumors?

A 62-year-old man with hypertension and atrial fibrillation is brought to the emergency department because of sudden onset visual changes. He stopped taking all of his medications 2 months ago. Blood pressure is 170/90 mm Hg and pulse is 108/min. He is alert and oriented to person but does not follow commands. His speech is fluent with normal cadence, but he uses frequent non-existent words and the content of his speech is nonsensical. He appears unaware of his speech impairment. He is unable to read a text out loud. Peripheral vision is diminished in the right upper visual fields bilaterally. This patient's presentation is most consistent with injury to which of the following labeled areas?

A 44-year-old woman comes to the physician because of pain and swelling below her left eye for 3 days. She has also had excessive watering from her eyes during this period. She has no history of serious illness and takes no medications. Her temperature is 37°C (98.6°F), pulse is 90/min, and blood pressure is 110/70 mm Hg. Examination shows erythema, tenderness, warmth, and swelling below the medial canthus of the left eye. There is purulent discharge from the lower lacrimal punctum on palpation of the swelling. The remainder of the examination shows no abnormalities. The discharge is sent for cultures. Which of the following is the most appropriate next step in management?

A 60-year-old man is brought to the emergency department because of a 30-minute history of dizziness and shortness of breath. After establishing the diagnosis, treatment with a drug is administered. Shortly after administration, the patient develops severe left eye pain and decreased vision of the left eye, along with nausea and vomiting. Ophthalmologic examination shows a fixed, mid-dilated pupil and a narrowed anterior chamber of the left eye. The patient was most likely treated for which of the following conditions?

A 27-year-old man comes to the physician because of pain and swelling in his right knee that began 3 days ago when he fell during football practice. He fell on his flexed right knee as he dove to complete a pass. He felt some mild knee pain but continued to practice. Over the next 2 days, the pain worsened and the knee began to swell. Today, the patient has an antalgic gait. Examination shows a swollen and tender right knee; flexion is limited by pain. The right knee is flexed and pressure is applied to proximal tibia; 8 mm of backward translation of the foreleg is observed. Which of the following is most likely injured?

A 65-year-old woman with hypertension comes to the emergency department because of sudden onset of a severe headache 2 hours ago. Her temperature is 34.7°C (94.5°F) and blood pressure is 189/115 mm Hg. Physical examination shows cold skin. A CT scan of the head shows a subarachnoid hemorrhage and she is started on appropriate pharmacotherapy. Damage to which of the following regions of the brain is most likely responsible for this patient's presentation?

A female newborn delivered at 37 weeks’ gestation develops respiratory distress immediately after birth. She was delivered vaginally to a 31-year-old woman, gravida 1, para 1. Pregnancy was complicated by gestational diabetes mellitus treated with insulin during the third trimester. The newborn's pulse is 136/min, respirations are 57/min, and blood pressure is 60/35 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 91% when the newborn is crying and a saturation of 85% at rest. Examination shows grunting breath sounds and perioral blue discoloration that improves when the patient cries. Lungs are clear to auscultation. Cardiac examination shows a split S2 during inspiration but no murmurs are heard. Femoral pulses are palpable bilaterally. A suction catheter cannot be passed through the nares. In addition to establishing an oral airway, which of the following is the most appropriate treatment for this patient's condition?

A 36-year-old woman comes to the physician because of a 2-week history of progressively worsening pain on the outer side of her left elbow. She does not recall any trauma to the area. The patient plays badminton recreationally. Examination shows tenderness over the lateral surface of the left distal humerus. The pain is reproduced by supinating the forearm against resistance. Which of the following is the most likely underlying cause of this patient's pain?