This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Lower limb, Subject name: Anatomy
Root value of achilles reflex ? 
Select and explain. 
A. L1,L2, B. L3,L4, C. S3, S4, D. S1,S2
D: S1,S2
Answer: D: S1,S2 
Explanation: The Achilles reflex checks if the S1 and S2 nerve roots are intact and could be indicative of sciatic nerve pathology . It is classically delayed in hypothyroidism . This reflex is usually absent in disk herniations at the L5--S1 level. A reduction in the ankle jerk reflex may also be indicative of peripheral neuropathy ref - pubmed.com