Anatomy clinical correlates Quiz: Ace Your Exams

An 18-year-old woman is brought to the emergency department by EMTs and police after a motor vehicle collision. The patient entered a highway and was struck by another vehicle at high speed. She was unrestrained and was ejected from her car. She arrives in the ED alert and oriented x3 and endorses severe pain in her neck and right axilla. Temperature is 97 F° (36.1 C°), pulse is 160/min, and blood pressure is 132/90 mm Hg. On physical examination, the right arm is internally rotated and adducted and flexed at the wrist with an extended forearm. The muscular tone of the right biceps, infraspinatus, and deltoid appears diminished. She has sensory loss along the lateral surface of the right arm, up to the thumb. Imaging of the cervical vertebrae does not reveal fractures, bleeding, or evidence of impingement. X-ray of the right upper extremity does not demonstrate dislocations or fractures. Which of the following best describes the anatomic localization of this patient’s lesion?