A 21-year-old man comes to the emergency department after suffering an injury during a football game. He was falling to the ground when he was struck forcefully from behind by the helmet of an opposing player. The patient was able to ambulate after the injury but has since had severe pain worsened by deep breaths. His blood pressure is 110/65 mm Hg, pulse is 110/min, and respirations are 16/min. On examination, there is bruising and tenderness over the left posterior chest wall. There is normal spinal range of motion and no midline tenderness. Gait and lower extremity neurologic examination are normal. Imaging studies reveal a fracture of the left 12th rib. Which of the following structures is most likely to be lacerated by the fractured bone?

Question

A 21-year-old man comes to the emergency department after suffering an injury during a football game.  He was falling to the ground when he was struck forcefully from behind by the helmet of an opposing player.  The patient was able to ambulate after the injury but has since had severe pain worsened by deep breaths.  His blood pressure is 110/65 mm Hg, pulse is 110/min, and respirations are 16/min.  On examination, there is bruising and tenderness over the left posterior chest wall.  There is normal spinal range of motion and no midline tenderness.  Gait and lower extremity neurologic examination are normal.  Imaging studies reveal a fracture of the left 12th rib.  Which of the following structures is most likely to be lacerated by the fractured bone?

Quizplus · Accepted Answer

11ec160b_3592_89ad_9249_4b5772503495_MD0001_00 The first 7 rib pairs are considered "true" ribs because their costal cartilage attaches directly to the sternum; the cartilage of the lower 5 pairs does not, and they are considered "false" ribs. Of these, the cartilage of ribs 8-10 attaches to the costal cartilage of the upper ribs. The 11th and 12th ribs are "floating" ribs, meaning that they are not bound to the anterior rib cage by cartilage. The left 12th rib overlies the parietal pleura medially and the kidney laterally. For this reason, the distal tip of the left 12th rib can be displaced into the retroperitoneum when fractured, lacerating the left kidney. (Choice A) The liver occupies much of the right upper quadrant of the abdominal cavity, where the 8th-11th ribs overlie the liver's posterior surface. The left lobe crosses the midline antero-inferior to the diaphragm, where it is not vulnerable to a displaced fragment from the 12th rib. (Choice C) The pancreas is a partially retroperitoneal organ that overlies the body of the second lumbar vertebra. Crushing abdominal trauma is the injury most likely to cause pancreatic damage. (Choice D) The spleen lies in the posterior superior portion of the left abdominal cavity. The left 9th, 10th, and 11th ribs overlie the spleen. (Choice E) The visceral pleura envelop the lungs. At rest, the inferior margin of the left lung lies at the level of the 10th rib in the mid-scapular line. During maximal inhalation, the lung may descend to the level of the most medial portion of the 12th rib, but fractures of ribs 1-6 have the greatest chance of damaging the visceral pleura. Educational objective: The left kidney lies immediately deep to the tip of the 12th rib.

A 21-Year-Old Man Comes to the Emergency Department After Suffering