More Pelvic Landmarks

The sacrum is the downward pointing triangular piece of bone that forms the bottom of the spine and connects the two halves of the pelvis at the rear. (The pubic bone joins the two halves of the pelvis at the front.)

Pelvic Landmarks: Note the ischio pubo ramus and ischial spines, marked in the image to the left and the upper and lower sciatic notches marked in both the image to the left and right. Also note how the piriformis passes through the upper sciatic notch above the ischial spine and how the obturator internus wraps around the back of the pelvis at the lower sciatic notch.

Pelvic Landmarks:
Note the ischio pubo ramus and ischial spines, marked in the image to the left and the upper and lower sciatic notches marked in both the image to the left and right. Also note how the piriformis passes through the upper sciatic notch above the ischial spine and how the obturator internus wraps around the back of the pelvis at the lower sciatic notch.

  • The tailbone forms the bottom point of the sacrum. To either side of the tailbone, and slightly lower than the bottom point of the tail bone are the two sitting bones, which I’ve already mentioned.
  • The ischiopuboramus are two rocker-like shaped bones that run from the sitting bones to the pubic bone. If you palpate or feel your sitting bones, you may be able to run your hands forwards and feel a continuous ridge of bone that connects your sitting bone to the pubic bone (one of each side.) That’s the ischiopuboramus (on one side.)
  • Moving upwards from the sitting bones, at about the level of the bottom of the tailbone are the ischial spines. These little spikes of bone stick inwards and help to define two concave cut outs at the rear edge of the pelvis:
  • Just below the ischial spine is a slight cutout called the inferior sciatic notch.
  • Just above the ischial spine is a half moon shaped notch called the superior sciatic notch.
  • Note the opening or hole at the bottom of each side of the pelvis, between the ischiopuboramus and the hip socket. These openings are called the obturator foramen.

The lower sciatic notch is the where the obturator internus muscle wraps around the back of the pelvis.

The upper sciatic notch is where the piriformis muscle passes through. (Since the piriformis attaches to the scarum and so crosses the SI Joint and the hip joint, it’s not included as a single hip joint muscle.)

The obturator foramen are covered on the outside by the obturator externus muscles and on the inside by the obturator internus muscles.

Mapping the Pelvis

Take the time to palpitate your pubic bone, your sitting bones, your sacrum and your hip crests.

Next put your awareness on your pubic bone. Feel it with your minds eye. From there move your awareness backwards from there along each of the ischiopuboramii (the rockers of the pelvis) to the sitting bones.

From the sitting bones move your awareness upwards to about the level of the bottom of the tailbone. Imagine the ischial spines sticking slightly inwards just above the bottom of the sitting bones.

From there you could move your awareness upwards, imagining the superior sciatic notch, and just above that the roughly L-shaped (or ear shaped) surface where the sacrum attaches to each side of the pelvis. Move upwards from here to the rear of the iliac crest. See if you can trace the top of the iliac crest with your minds eye.

Travel to the front of each crest, then move your awareness downwards and inwards, back to the pubic bone.

If you like, take the visualization a little further. Draw a line around the inside of the pelvis from the top of the sacrum at the rear to the top of the pubic bone at the front. This is the arcuate line.

Just below the arcuate line, near the front of the pelvis, imagine the two openings, the obturator foramen on either side of the pelvis, between the arcuate line and the bottom of the ischio pubo ramii.

Up next

Landmarks of the Thigh Bone