This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Lower Extremity, Subject name: Anatomy
Which of the following for unlocking of knee? 
Select and explain. 
A. Navicular, B. Calcaneum, C. Talus, D. Cuboid
C: Talus
Answer: C: Talus 
Explanation: Ans. C. Talusa. Talus has no muscle attachment.b. Talus also has a precarious blood supply because blood enters it distally ie. Retrograde blood supply.c. Remember incus in ear also has no muscle attachment.