A 21-year-old man is brought to the emergency department following an assault. He was attempting to escape and turned away just as his attacker lunged toward him from behind with a knife. The patient suffered a 4-cm-wide penetrating injury with significant associated blood loss. Following initial stabilization, he is transferred to the operating room. Surgical exploration reveals injury to a muscle that assists in internal rotation of the arm and is innervated by the thoracodorsal nerve. Which of the following muscles depicted in the cadaveric specimen is most likely injured in this patient?

Question

A 21-year-old man is brought to the emergency department following an assault.  He was attempting to escape and turned away just as his attacker lunged toward him from behind with a knife.  The patient suffered a 4-cm-wide penetrating injury with significant associated blood loss.  Following initial stabilization, he is transferred to the operating room.  Surgical exploration reveals injury to a muscle that assists in internal rotation of the arm and is innervated by the thoracodorsal nerve.  Which of the following muscles depicted in the cadaveric specimen is most likely injured in this patient?

Quizplus · Accepted Answer

11ec160b_35e1_e2d3_9249_23d05b9c1094_MD0001_00 The latissimus dorsi is a large thoracolumbar muscle that contributes to forceful movement of the humerus. It originates in a broad area spanning from the iliac crest and lumbar fascia to the spinous processes of T7-12 and lower ribs. It inserts at the bicipital groove of the humerus. The latissimus dorsi is innervated by the thoracodorsal nerve, with fibers originating from the C6-8 nerve roots. Primary functions include extension, adduction, and internal rotation of the humerus. Due to its broad area and exposed location, the latissimus dorsi is vulnerable to injury from external trauma. It is also frequently injured in sports requiring forceful downward movement of the humerus, such as throwing, climbing, or swinging a tennis racket overhead. (Choice A) The deltoid is innervated by the axillary nerve, and its primary action is abduction of the arm. It can be injured due to sudden or forceful loading of the arm while in abduction. (Choice B) The infraspinatus is innervated by the suprascapular nerve and serves to externally rotate the arm. It is most commonly injured in association with the supraspinatus due to falls or overuse in older patients. (Choice D) The trapezius is a large muscle in the upper back and neck that serves to elevate, rotate, and stabilize the scapula. It is primarily innervated by cranial nerve XI. The trapezius is frequently injured in rear-end (whiplash) motor vehicle accidents. (Choice E) The triceps is innervated by the radial nerve (C6-8, T1) and is the primary muscle involved in extension of the elbow. Educational objective: The latissimus dorsi is a large thoracolumbar muscle that originates from the iliac crest and lumbar fascia to the spinous processes of T7-12 and lower ribs, and inserts at the bicipital groove of the humerus. It is innervated by the thoracodorsal nerve. Primary functions include extension, adduction, and medial (internal) rotation of the humerus.

A 21-Year-Old Man Is Brought to the Emergency Department Following