The upper part of the gluteus maximus, by its attachment to the ilium, pulls the ilium posteriorly into nutation. The lower part, by its attachment to the sacrum, pulls the sacrum into counternutation.

Acting together, the combined action of these two divisions pull the entire pelvis posteriorly to extend the pelvis and raise the trunk, which is helpful when lifting a heavy object; thereby demonstrating iliac nutation and sacral counternutation occurring concurrently.

Origin:
Superior Division: Outer ilium, posterior gluteal line, aponeurosis of the erector spinae and gluteus medius muscles [1]^p686 [2]^p566
Inferior Division: Posterior inferior side of sacrum, coccyx, and parts of the sacrotuberous and posterior sacroiliac ligaments [3]^p81 [1]^p686 [2]^p566

Insertion: [3]^p81 [1]^p686 [4]^p1368-69
Superior Division: Iliotibial band
Inferior Division: Gluteal tuberosity and iliotibial band

Functions:
Superior Division [1]^p685-687

• Laterally rotates the thigh
• Causes hip extension by pulling the ilium posteriorly [1, 4]
• Abducts the hip
•  Blends with the connective tissue of the superficial erector spinae and multifidus to form the gluteal raphe: this triad of muscles form a powerful extensor mechanism spanning the lumbar spine, pelvis, and femur
• With the contralateral latissimus dorsi, it provides a compressive force that is perpendicular to the sacroiliac joint [5].
• Loading of the gluteus maximus has been shown to promote nutation [6-8].

Inferior Division [1]^p685-687 [4]^p1369

• Causes lateral thigh rotation
• Causes hip adduction
• Through the fascia lata tract, it helps stabilize the femur on the tibia when the knee extensors are relaxed.
• Pulls the sacral apex anteriorly, bringing the sacral base posteriorly and superiorly [9], into counternutation
• Most texts consider the gluteus maximus to be one muscle, with one set of functions, pelvic extension. However, the gluteus maximus is bilaminar, having two separate divisions and functions [1]^p686 [4]^p1368.

Oatis stated that “the superior portion lies superior to the axis of abduction and adduction, while the inferior portion lies inferior to it.” As a result, the superior, iliac portion abducts the hip, while the inferior, sacral portion adducts it.

Gray’s Anatomy [2]^p566 mentions the upper and lower divisions but does not define them.

Although the gluteus maximus can extend the pelvis as a whole, it appears to act separately on the superior and inferior divisions when activated in the anatomically neutral posture. By pulling the ilium posteriorly, the superior division promotes nutation. On the other hand, by pulling the sacral apex anteriorly, the lower division promotes counternutation.

There is evidence that the gluteus maximus, along with the long head of the biceps femoris and piriformis, has a dual function: it can promote both nutation and counternutation separately or simultaneously. When stooped, the upper-division rotates the ilia posteriorly into nutation, as usual. The inferior division is connected to the caudal part of the sacrum and the sacrotuberous ligament, where its action pulls the sacral base posteriorly and superiorly into counternutation. Because this dual-action occurs simultaneously only, or mainly, during hip flexion, it was thought to help rotate the entire pelvis posteriorly when lifting heavyweight from a stooped position [8, 10].

DonTigny [9] discusses the dual function of the gluteus maximus. He stated that the iliac origin induces extension (nutation) but the sacral origin functions to straighten the sacrum (counternutation). He refers to his illustration of the gluteus maximus and piriformis (a counternutator) as sharing a similar line of drive when he says “Note how the sacral origin of the gluteus maximus works with the piriformis muscle to support the function of the sacrotuberous ligament and to straighten the sacrum as it pulls the body forward…”

The iliac division extends the hip (nutation). If the inferior, sacral division acts independently, it vectors of pull indicate that it rotates the sacral apex anteriorly (counternutating the sacrum), in keeping with the principle of nutation/counternutation. Accordingly, along with the piriformis and biceps femoris, the sacral division of the gluteus maximus attaches to the sacrotuberous ligament. By tensioning this ligament, these muscles act to limit nutation, demonstrating a counternutation function.

It should be noted that all three muscles have position-dependent functions expressing opposing actions. The piriformis can rotate the femur internally or externally. The biceps femoris and gluteus maximus can nutate the innominates or counternutate the sacrum. The gluteus maximus can also adduct or abduct the femur.

In general, it appears that internal rotation and abduction are functions of nutation, while external rotation and adduction are functions of counternutation, although this is not thought out well at this point.

When texts discuss the gluteus maximus, they are almost always referring to the superior division because the action of the inferior division is not well recognized. From this viewpoint, it is my opinion that the separate functions of the gluteus maximus should be further delineated in any and all future discussions of the muscle.

Snijders [11] mentions that “Tension in the gluteus muscles can result in sacroiliac joint compression (nutation) because these muscles insert, in part, onto layers of the external fascia superficial to the sacrum with connections to the thoracolumbar fascia.”

An important point to consider is Gracovetsky’s [12]’s analysis of shoulder counter rotation occurring during gait. When the right leg is in extension (pelvis rotating to the right with right gluteus maximus contracted), they found that the right shoulder would rotate to the left. The contracted muscles would include the right pectoralis major, anterior deltoid and anterior serratus and the left trapezius, posterior deltoid, and latissimus dorsi. However, with a right sacroiliac nutation lesion, it appears that the left latissimus dorsi and right gluteus maximus would be inhibited in order to protect the right sacroiliac joint. Conceptually, this would lead to coordination difficulties that may be expressed by reduced balance and performance.

References:

1. Oatis, C.A., Kinesiology. The Mechanics and Pathomechanics of Human Movement. 2004: Lippincott Williams & Wilkins.
2. Warwick, R. and P.L. Williams, eds. Gray’s Anatomy. 35 ed., ed. R. Warwick and P.L. Williams. 1973, W.B. Saunders Company: New York.
3.  McMinn, R.M.H. and R.T. Hutchings, Color Atlas of Human Anatomy. 1977, Chicago: Medical Publishers, Inc.
4. Standring, S., et al., eds. Gray’s Anatomy. 40th ed. 2008, Churchill Livingstone: London.
5. Vleeming, A., et al., The posterior layer of the thoracolumbar fascia. Its function in load transfer from spine to legs. Spine, 1995. 20(7): p. 753-8.
6. Vleeming, A., R. Stoeckart, and C. Snidjers. The Sacrotuberous Ligament: A Conceptual Approach to its Dynamic Role in Stabilizing the Sacroiliac Joint. in Proceedings of the 1st Interdisciplinary World Congress on Low Back Pain and its Relation to the Sacroiliac Joint. 1992. San Diego: ECO.
7. Vleeming, A., et al., The function of the long dorsal sacroiliac ligament: its implication for understanding low back pain. Spine, 1996. 21(5): p. 556-62.
8. Vleeming, A., et al., The role of the sacroiliac joints in coupling between spine, pelvis, legs and arms., in Movement, Stability, and Low Back Pain, A. Vleeming, et al., Editors. 1997, Churchill Livingstone. p. 53-71.
9. DonTigny, R.L., Critical Analysis of the Functional Dynamics of the Sacroiliac Joints as They Pertain to Normal Gait. JOM, 2005. 27(1): p. 3-10.
10. van Wingerden, J.P., et al., A functional-anatomical approach to the spine-pelvis mechanism: interaction between the biceps femoris muscle and the sacrotuberous ligament. Eur Spine J, 1993. 2(3): p. 140-4.
11. Snijders, C.J., Transfer of Lumbosacral Load to Iliac Bones and Legs: Part 1 – Biomechanics of Self-Bracing of the Sacroiliac Joints and its Significance for Treatment and Exercise. Clinical Biomechanics, 1993a. 8: p. 285-294.
12. Gracovetsky, S. and H. Farfan, The optimum spine. Spine, 1984. 11(6): p. 543-73.