What myotome pattern corresponds to S3?

The myotome pattern corresponding to S3 is not associated with a specific motor function, which is why the correct response is that S3 corresponds to "none."

In spinal anatomy, myotomes are the segments of muscles that are innervated by specific spinal nerves. The S3 segment is part of the sacral plexus, and although it contributes to sensation in the pelvic region, there is no primary muscle action directly tied to this level like there is with other lumbo-sacral nerve roots involved in major movements.

The other options relate to specific actions by muscles innervated by different segments of the lumbar or sacral nerves. Plantarflexion is primarily innervated by S1 and S2, hip extension is linked to lumbar and sacral nerves serving the gluteal muscles, and knee flexion is associated with muscles innervated by the sciatic nerve, which comes from L5, S1, and S2. Thus, S3’s lack of a primary myotome designation makes it unique among these options.