Posterior sacrum, sacroiliac somatic dysfunction results in spasms of which muscle?

Posterior sacrum, sacroiliac somatic dysfunction results in spasms of which muscle?

• A. Piriformis
• B. Gluteus medius
• C. Quadratus lumborum
• D. Iliopsoas

Answer: (A)

The muscle most likely to spasm with a posterior sacral somatic dysfunction is the piriformis. This muscle originates from the anterior surface of the sacrum and travels through the greater sciatic foramen to insert on the femur, with innervation from the sacral plexus (nerve to piriformis from S1–S2). When the sacrum is stuck in a posterior pattern, the piriformis is especially prone to become hypertonic as it helps stabilize the sacral area, leading to a painful spasm. The other muscles listed—gluteus medius, quadratus lumborum, and iliopsoas—are not as directly connected to the sacrum or sacral innervation in this specific dysfunction pattern, so they’re less likely to be the primary spasm source.

The muscle most likely to spasm with a posterior sacral somatic dysfunction is the piriformis. This muscle originates from the anterior surface of the sacrum and travels through the greater sciatic foramen to insert on the femur, with innervation from the sacral plexus (nerve to piriformis from S1–S2). When the sacrum is stuck in a posterior pattern, the piriformis is especially prone to become hypertonic as it helps stabilize the sacral area, leading to a painful spasm. The other muscles listed—gluteus medius, quadratus lumborum, and iliopsoas—are not as directly connected to the sacrum or sacral innervation in this specific dysfunction pattern, so they’re less likely to be the primary spasm source.