Review Question - QID 219191

A 36-year-old male is brought to the trauma bay after being involved in a head-on motor vehicle accident. Radiographs are obtained and demonstrate a comminuted calcaneus fracture. After applying a bulky Jones splint, a CT scan is obtained, demonstrating marked displacement of the posterior facet of the calcaneus. The patient is neurovascularly intact, but you note limited motion of the hallux when compared to the uninjured extremity. What is the origin of the tendon which often becomes entrapped between the posterior facet of the talus and the posterior facet fragment of the fractured calcaneus?