Question:easy
S1 and S2 nerve roots are checked by which reflex?
S1 and S2 nerve roots are checked by which reflex?
Show Hint
S1-S2 maps to the ankle jerk, also known as the Achilles reflex.
Updated On: Jun 24, 2026
- Knee jerk
- Patellar reflex
- Calcaneal reflex
- None
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: Anchor each tendon reflex to its root level. The biceps jerk is C5-C6, the triceps jerk is C7-C8, the knee jerk is L3-L4, and the ankle jerk is S1-S2.
Step 2: The question asks for the S1-S2 reflex, so the answer must be the ankle reflex. This same reflex carries several names: calcaneal reflex and Achilles reflex, all describing a strike on the Achilles tendon that produces plantar flexion at the ankle.
Step 3: Discard the knee-level options. The knee jerk and the patellar reflex are simply two names for one reflex that evaluates L3-L4, well above the sacral roots in question.
Step 4: The calcaneal reflex is the unique S1-S2 test, making it the correct choice.
\[\boxed{\text{Calcaneal reflex}}\]
Step 2: The question asks for the S1-S2 reflex, so the answer must be the ankle reflex. This same reflex carries several names: calcaneal reflex and Achilles reflex, all describing a strike on the Achilles tendon that produces plantar flexion at the ankle.
Step 3: Discard the knee-level options. The knee jerk and the patellar reflex are simply two names for one reflex that evaluates L3-L4, well above the sacral roots in question.
Step 4: The calcaneal reflex is the unique S1-S2 test, making it the correct choice.
\[\boxed{\text{Calcaneal reflex}}\]
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