Which nerve roots are tested by elbow extension response when evaluating the triceps tendon reflex?

Which nerve roots are tested by elbow extension response when evaluating the triceps tendon reflex?

• A. C5 to C6 nerve roots assessed via elbow extension response.
• B. C6 to C7 nerve roots assessed via elbow extension response.
• C. L3 to L4 nerve roots assessed via knee extension response.
• D. L5 to S1 nerve roots assessed via plantarflexion response.

Answer: (B)

The elbow extension reflex (triceps reflex) primarily assesses the spinal nerve roots that feed the triceps via the radial nerve, which are the C7 and C8 levels. When you strike the triceps tendon, a monosynaptic reflex arc triggers the triceps to contract, causing elbow extension. A normal reflex indicates these roots are functioning, while diminished or absent reflex suggests an issue at or affecting those C7-C8 levels. This is different from other reflexes: for example, the biceps reflex involves C5-C6, the brachioradialis is mainly C6, knee extension tests L3-L4, and plantarflexion tests S1-S2.

The elbow extension reflex (triceps reflex) primarily assesses the spinal nerve roots that feed the triceps via the radial nerve, which are the C7 and C8 levels. When you strike the triceps tendon, a monosynaptic reflex arc triggers the triceps to contract, causing elbow extension. A normal reflex indicates these roots are functioning, while diminished or absent reflex suggests an issue at or affecting those C7-C8 levels. This is different from other reflexes: for example, the biceps reflex involves C5-C6, the brachioradialis is mainly C6, knee extension tests L3-L4, and plantarflexion tests S1-S2.