This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
Structures passing through lesser sciatic foramen are all, except: 
Select and explain. 
A. Pudendal nerve, B. Internal pudendal aery, C. Nerve to obturator externus, D. Tendon of obturator internus
C: Nerve to obturator externus
Answer: C: Nerve to obturator externus 
Explanation: Structures passing through lesser sciatic foramen are tendon of obturator internus muscle, nerve to obturator internus, pudendal nerve, internal pudendal aery and vein.Structures passing through greater sciatic foramen are:PiriformisSciatic nervePosterior cutaneous nerve of thighSuperior and inferior gluteal nerveNerve to obturator internus and quadratus femorisPudendal nerveSuperior and inferior gluteal nerves and aeriesInternal pudendal aery and vein