A 22-year-old man is brought to the emergency department after being involved in a fight at a nearby bar. The patient's respiratory rate is 28/min, blood pressure is 88/60 mm Hg, and heart rate is 114/min. Physical examination shows a penetrating right-sided stab wound along the upper surface of the clavicle between the lateral border of the sternum and the midclavicular line. Which of the following structures was most likely injured?

Question

A 22-year-old man is brought to the emergency department after being involved in a fight at a nearby bar.  The patient's respiratory rate is 28/min, blood pressure is 88/60 mm Hg, and heart rate is 114/min.  Physical examination shows a penetrating right-sided stab wound along the upper surface of the clavicle between the lateral border of the sternum and the midclavicular line.  Which of the following structures was most likely injured?

Quizplus · Accepted Answer

11ec160b_35db_5314_9249_0df2e60dd536_MD0001_00 In patients with neck injuries, it is important to remember that the lung apices and cervical pleura extend above the clavicle and first rib through the superior thoracic aperture. Stab wounds immediately above the clavicle and lateral to the manubrium can puncture the pleura and cause pneumothorax, tension pneumothorax, or hemothorax. This patient most likely has a tension pneumothorax as a result of his pleural injury. As an increasing volume of air accumulates within the pleural space, the lungs and mediastinum deviate to the opposite side of the chest. Increased pressure within the chest cavity decreases systemic venous return to the heart, lowering cardiac output. Signs and symptoms of tension pneumothorax include tachycardia, hypotension, tachypnea, hypoxemia, and hyperresonance to percussion and absence of breath sounds on the affected side. Treatment is with emergency needle thoracostomy or chest tube. (Choice A) The accessory nerve (cranial nerve XI) innervates the sternocleidomastoid and trapezius muscles. This nerve may be injured during surgery involving the posterior triangle of the neck (a region bounded by the sternocleidomastoid muscle, trapezius muscle, and clavicle). (Choice B) The ansa cervicalis arises from the C1, C2, and C3 nerve roots and innervates the sternohyoid, sternothyroid, and omohyoid muscles of the anterior neck. Penetrating trauma to the neck above the cricoid cartilage can injure this nerve. (Choice C) The carotid body, which contains O₂, CO₂, and H⁺ chemoreceptors, lies at the bifurcation of the common carotid artery (just inferior to the hyoid bone). (Choice D) The inferior thyroid artery arises from the thyrocervical trunk and courses posterior to the carotid artery and jugular vein to supply the inferior pole of the thyroid gland. Injury to the inferior thyroid artery is commonly associated with hoarseness because it runs adjacent to the recurrent laryngeal nerve. Educational objective: The lung apices extend above the level of the clavicle and first rib through the superior thoracic aperture. Penetrating injury in this area may lead to pneumothorax, tension pneumothorax, or hemothorax.

A 22-Year-Old Man Is Brought to the Emergency Department After