Piriformis Muscle, Posterior View

Description

Seen from a posterior perspective in a male pelvis, the paired piriformis muscles are highlighted as they course laterally from the anterior surface of the sacrum, pass through the greater sciatic foramen, and converge toward the superior aspect of the greater trochanter of the femur. Midline, the sacrum and coccyx sit inferior to the lower lumbar vertebrae, flanked by the right and left hip bones where the ilium rises superiorly and the ischium and pubis contribute to the acetabulum. Inferior to the acetabula, the proximal femora anchor the hip joints. Clear bony landmarks. Clinical interest in the piriformis comes from its relationship to the sciatic nerve and its position as a deep external rotator in the gluteal region. When the muscle hypertrophies, spasms, or becomes fibrotic after trauma, it can narrow the infrapiriform space and irritate the sciatic nerve, producing buttock pain with radiating symptoms that mimic L5 or S1 radiculopathy, yet often spare lumbar imaging findings. This posterior layout also helps teach why hip flexion changes piriformis function, shifting from external rotation in extension toward abduction with the hip flexed. Use this plate in gross anatomy and musculoskeletal medicine teaching to orient learners to the sacrum, pelvic ring, and deep gluteal space before discussing sciatica differentials and posterior hip approaches. It also fits well in textbooks or patient education materials covering piriformis syndrome, deep gluteal pain, and injection planning with surface anatomy landmarks referenced to the sacrum and greater trochanter. Anatomical accuracy verified by SciePro's Medical Advisory Board.