Review Question - QID 218724

A 14-year-old male presents to your pediatric emergency department after jumping to spike a ball at the net in a high school volleyball game. There is significant pain and crepitus over the tibial tubercle with overlying swelling and ecchymosis. He is neurovascularly intact. Radiographs demonstrate a type III tibial tubercle fracture. You place him in a long leg splint for comfort overnight and schedule him for open reduction and internal fixation the following morning. However, you get a phone call from his nurse several hours later stating his pain is increasing despite increasing analgesic use and he is becoming increasingly anxious. She is concerned about compartment syndrome. Injury to what structure is most likely responsible for these symptoms?