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: Surgery
Which of the following is not a diahrosis ? 
Select and explain. 
A. Elbow joint, B. Interphalangeal joint, C. Skull sutures, D. Hip joint
C: Skull sutures
Answer: C: Skull sutures 
Explanation: Ans. is 'c' i.e., Skull sutures Functional classification of joints (movement) Joints can also be classified functionally according to the type and degree of movement they allow: Synahrosis - Permits little or no mobility. Most synahrosis joints are fibrous joints (e.g., skull sutures). Amphiahrosis - Permits slight mobility. Most amphiahrosis joints are cailaginous joints (e.g., interveebral discs). Diahrosis - Freely movable. All diahrosis joints are synol joints (e.g., shoulder, hip, elbow, knee, etc.), and the terms "diahrosis" and "synol joint" are considered equivalent by Terminologia Anatomica