USMLE Step 1 Practice Test 2026

About the USMLE Step 1 exam

Also searched as: USMLE practice questions. It's the same exam — USMLE Step 1 is the official name.

The US Medical Licensing Examination - Step 1 (USMLE Step 1) is a medical examination administered in USA. It is designed to assess candidates' knowledge and proficiency across 7 key subject areas including Anatomy, Biochemistry, Pharmacology, Pathology. This exam is widely recognized as an essential benchmark for medical students and practitioners.

Use short USMLE Step 1 practice sets to identify topics to revisit. Choose a subject and difficulty, answer questions, then review the explanations. New accounts get 30 question credits; further new questions use paid credits. Retaking previously seen questions is free.

Whether you're a first-time candidate or retaking the USMLE Step 1 to improve your score, InfinityMock helps you identify your strengths and weaknesses through detailed performance analytics. Our platform covers Anatomy, Biochemistry, Pharmacology, Pathology, Physiology, Microbiology, Behavioral Sciences, with questions available at Easy, Medium, and Hard difficulty levels. Track your progress, review detailed explanations, and build the confidence you need to pass on exam day.

USMLE Step 1 — quick answers

USMLE Step 1 at a glance

8 free USMLE Step 1 practice questions (2026)

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1. A 24-year-old man falls from a motorcycle and lands on his right shoulder. Physical examination shows decreased sensation over the lateral aspect of his shoulder and weakness in initiating arm abduction. Which of the following nerves is most likely injured?

   • Axillary nerve
   • Musculocutaneous nerve
   • Suprascapular nerve
   • Radial nerve
   Show answer & explanation

   Answer: A. Axillary nerve

   The axillary nerve (C5-C6) innervates the deltoid and teres minor muscles and provides sensory innervation to the lateral shoulder. Injury commonly occurs with anterior shoulder dislocation or proximal humerus fracture, causing loss of sensation in this region and weak shoulder abduction.

   Topic: Anatomy · easy

2. A 62-year-old man presents with severe chest pain. Electrocardiogram shows ST-segment elevation in leads II, III, and aVF. Coronary angiography reveals occlusion of the artery that supplies the posteromedial papillary muscle of the mitral valve. This artery typically arises from which of the following?

   • Left anterior descending artery
   • Left circumflex artery
   • Right coronary artery
   • Left main coronary artery
   Show answer & explanation

   Answer: C. Right coronary artery

   The posteromedial papillary muscle has a single blood supply from the posterior descending artery (PDA), which arises from the right coronary artery (RCA) in right-dominant individuals (representing ~85% of the population). The anterolateral papillary muscle, by contrast, has a dual blood supply.

   Topic: Anatomy · medium

3. A 3-week-old male infant is brought to the clinic due to a persistent bulge in his right scrotum that increases in size when he cries. Ultrasound confirms a fluid collection surrounding the testis that communicates with the peritoneal cavity. Which of the following embryological structures failed to obliterate in this patient?

   • Processus vaginalis
   • Urachus
   • Vitelline duct
   • Gubernaculum
   Show answer & explanation

   Answer: A. Processus vaginalis

   Failure of the processus vaginalis to obliterate allows peritoneal fluid to accumulate in the tunica vaginalis, causing a communicating hydrocele, or allows bowel loops to herniate, resulting in an indirect inguinal hernia.

   Topic: Anatomy · easy

4. A 32-year-old woman experiences fecal incontinence and decreased sensation in the perineal region following a difficult vaginal delivery with midline episiotomy. Which of the following nerves was most likely injured?

   • Pudendal nerve
   • Ilioinguinal nerve
   • Obturator nerve
   • Genitofemoral nerve
   Show answer & explanation

   Answer: A. Pudendal nerve

   The pudendal nerve (S2-S4) innervates the perineum and external urethral and anal sphincters. It is vulnerable to compression or stretch injury during prolonged labor, leading to fecal and urinary incontinence and perineal sensory loss.

   Topic: Anatomy · medium

5. A 45-year-old woman undergoes a superficial parotidectomy for a benign tumor. Postoperatively, she is unable to close her eye tightly on the affected side and has asymmetric smiling. Which of the following cranial nerves was most likely damaged?

   • Trigeminal nerve
   • Facial nerve
   • Glossopharyngeal nerve
   • Accessory nerve
   Show answer & explanation

   Answer: B. Facial nerve

   The facial nerve (CN VII) exits the stylomastoid foramen and passes through the parotid gland, where it divides into its five terminal motor branches. Damage during parotidectomy leads to ipsilateral facial paralysis.

   Topic: Anatomy · easy

6. A 65-year-old man presents with sudden-onset hoarseness, difficulty swallowing, loss of pain and temperature sensation on the left side of his face, and loss of pain and temperature on the right side of his body. On examination, he also has left-sided miosis, ptosis, and anhidrosis. Which of the following arteries is most likely occluded?

   • Anterior spinal artery
   • Posterior inferior cerebellar artery
   • Anterior inferior cerebellar artery
   • Basilar artery
   Show answer & explanation

   Answer: B. Posterior inferior cerebellar artery

   These symptoms describe lateral medullary (Wallenberg) syndrome, which is caused by occlusion of the posterior inferior cerebellar artery (PICA). Key structures affected include the nucleus ambiguus (dysphagia/hoarseness), spinal trigeminal tract (ipsilateral facial loss of pain/temp), spinothalamic tract (contralateral body loss of pain/temp), and sympathetic fibers (Horner syndrome).

   Topic: Anatomy · hard

7. A newborn is evaluated for micrognathia, low-set ears, cleft palate, and a small mandible. Genetic testing reveals a chromosomal deletion. The structures affected in this infant are primarily derived from which of the following pharyngeal arches?

   • First arch
   • Second arch
   • Third arch
   • Fourth arch
   Show answer & explanation

   Answer: A. First arch

   The mandible, maxilla, zygomatic bone, incus, and malleus, as well as the muscles of mastication, are derived from the first pharyngeal arch. Abnormal development results in craniofacial anomalies like those seen in Pierre Robin sequence or Treacher Collins syndrome.

   Topic: Anatomy · medium

8. A 54-year-old male with chronic alcoholic cirrhosis presents with hematemesis. Upper endoscopy reveals actively bleeding esophageal varices. These varices represent an anastomosis between which of the following pairs of veins?

   • Left gastric vein and azygos vein
   • Superior rectal vein and middle/inferior rectal veins
   • Paraumbilical veins and superficial epigastric veins
   • Splenic vein and renal vein
   Show answer & explanation

   Answer: A. Left gastric vein and azygos vein

   Esophageal varices occur due to portal hypertension, causing backup from the left gastric vein (portal system) into the esophageal/azygos veins (systemic system).

   Topic: Anatomy · medium

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USMLE Step 1 Exam Subjects

Available practice subjects: Anatomy, Biochemistry, Pharmacology, Pathology, Physiology, Microbiology, Behavioral Sciences. Select a subject for focused preparation. Coverage is not a guarantee of the complete official syllabus.

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