Piriformis

Scientific basis

The piriformis muscle originates on the anterior surface of the sacrum and attaches to the greater trochanter of the femur. It passes through the greater sciatic notch and is a major anatomical landmark of the deep gluteal region. Several nerve structures pass close to it; in particular, the pudendal nerve leaves the pelvis by passing below the piriformis before curving around the region of the ischial spine. The sciatic nerve runs in immediate proximity to the piriformis, most often below it; anatomical variants exist in which part of the nerve passes through the muscle. This proximity explains why some buttock pain radiating into the lower limb is associated, in everyday language, with the term sciatica, hence the expressions "false sciatica" and piriformis syndrome.

Blue Portance / SBNFA™ reading

In an SBNFA™ reading, the piriformis is part of a functional unit combining the pelvis, sacrum, hip, deep muscles, fascia and nerve structures. Its interest lies in the mechanical relationships it maintains with neighboring structures and in the adaptations of the pelvic complex as a whole.

Contribution to the analysis of sitting

Sitting influences the relative position of the pelvis and hips as well as the level of activity of the pelvic-gluteal musculature. The possibility of regularly changing orientation and support can therefore be analyzed alongside this muscular organization.

Not to be confused with

Obturator internus, another deep muscle of the pelvic region.

Sources and scope

• Probst, Stout and Hunt (2019): anatomy, diagnosis and treatment of piriformis syndrome, a narrative review
• Yang et al. (2026): variations in the course of the pudendal nerve and its relationships with pelvic structures