Massage.
LandmarkBackDraft

Sacrum

The flat, triangular bone at the base of the spine, wedged between the two hip bones.

BoneSacrum
RegionBack

Find it

  1. Client prone, draped to just below the top of the sacrum.
  2. Place the flat of your hand between the two PSIS dimples: the firm, flat bony plate under your palm is the sacrum.
  3. Run your fingertips down the midline to feel the small bumps of the median sacral crest (the fused spinous processes).
  4. Feel its sides narrowing towards the tailbone (coccyx); only work as low as the client has agreed to and the draping allows.

Multifidus arises from the grooves either side of the sacral midline, and erector spinae and latissimus dorsi (through the thoracolumbar fascia) also attach to the back of the sacrum. Gluteus maximus takes fibres from the lower sides of the sacrum and coccyx.

Piriformis arises from the front (pelvic) surface, so it cannot be felt directly here. The sacrotuberous and sacrospinous ligaments attach to the lower sides.

Muscles attaching or palpated here

  • Deep hip rotators — Six small, deep muscles behind the hip joint, running from the pelvis to the top of the femur, that laterally rotate the hip and steady the head of the femur in its socket.
  • Erector spinae — Three long columns of muscle (iliocostalis, longissimus and spinalis) running beside the spine from the sacrum to the skull that extend and side-bend the back and hold the trunk upright.
  • Gluteus maximus — The largest and most superficial buttock muscle, and the main extensor of the hip.
  • Latissimus dorsi — Broad, flat, fan-shaped muscle of the lower and middle back that extends, adducts and medially rotates the arm.
  • Multifidus — Series of short, deep muscle bundles filling the groove beside the spinous processes from the sacrum to C2 that extend and steady each segment of the spine.
  • Piriformis — Flat, pear-shaped deep hip muscle running from the front of the sacrum to the greater trochanter that laterally rotates the hip.

Sources

  1. Wikipedia: Sacrum
  2. Gray's Anatomy (1918), The Sacral and Coccygeal Vertebrae (Bartleby, archived)
  3. Wikipedia: Gluteus maximus