Rationale: The anatomical variant of the distal biceps femoris muscle with regard to common peroneal nerve entrapment neuropathy (CPNe) was suggested through magnetic resonance images (MRI) study.
Patient concerns: An unusual variant of distal biceps femoris muscle was observed in 78 years old male cadaver.
Diagnoses: The short head of biceps femoris muscle (SHBFM) was extended more distal and posteriorly.
Intervention: The popliteal area was dissected at knee joint level in a cadaveric limb.
Outcomes: Common peroeal nerve (CPN) was situated within tunnel formed between the lateral head of the gastrocnemius muscle (LGCM) and the SHBFM. Also, the length of tunnel was 4.4 cm.
Lessons: The case illustrated here, to the best of our knowledge, is the first one with cadaveric findings of variant of distal biceps femoris muscle associated with CPNe. The tunnel formed between the more posterior or distal extension of the SHBFM and the LGCM could be possible entrapment area of CPN, clinically.