June 6, 2023

Gluteus Maximus: Superficial and Deep Fibers

Learn about the anatomy of the gluteus maximus and its superficial and deep fibers. Discover the functions and exercises to strengthen this muscle.

Brent Brookbush

DPT, PT, MS, CPT, HMS, IMT

Research Review: Gluteus Maximus: Superficial & Deep Fibers

By Stefanie DiCarrado DPT, NASM CPT & CES

Edited by Brent Brookbush DPT, MS, PES, CES, CSCS, ACSM H/FS

Original Citation: Gibbons, S.G.T. (2004) The anatomy of the deep sacral part of the gluteus maximus and the psoas muscle: A clinical perspective. Proceeds of: The 5th interdisciplinary World Congress on Low Back Pain. November 7-11, Melbourne, Australia

Why is this relevant?: The gluteus maximus muscle is most often thought of as solely a powerful hip extensor and external rotator of the hip. However, cadaver dissections has revealed a deep layer of the gluteus maximus that only crosses the sacroiliac joint (SIJ). This may indicate that the gluteus maximus contribute more to SIJ and pelvic girdle stabilization than originally thought.

Study Summary:

Study Design	Descriptive
Level of Evidence	Level VI: Evidence from a single descriptive or qualitative study
Subject Demographics	Age: NA Gender: NA Characteristics: 12 cadavers; 24 gluteus maximi dissected
Outcome Measures	NA
Results	General Fibrous Attachments: 16 of the dissected glutei had "fibrous attachements" to the lateral sacrum and iliac crest; the remaining 8 having strong fascial attachments continuous with the multifidi aponeurosis & fascia on the posterolateral sacrum 3 Layers Identified: superficial sacral fibers, deep sacral fibers, deep ilium fibers Superficial Sacral Fibers: Originated on the sacrum and predominately blended into the iliotibial band arranged in bands of 7-10 fascicles (a small number also attached to the gluteal tuberosity in 20 muscles) Deep Ilium Fibers: Predominately attached to the gluteal tuberosity in all muscles Deep Sacral Fibers: Present in all muscles; these fibers only crossed the SIJ and were continuous with the fascia of the deep hip intrinsic muscles and ischiococcygeus muscle. Superiorly: Fibers crossed the SIJ to the posterior pelvic brim (lateral to the posterior superior iliac spine - PSIS) Inferiorly: Short fibers (1-3cm) obliquely ran inferolaterally from the superior lateral sacrum to the posterior ischial spine, ischial tuberosity (IT), and sacrotuberous ligament All though the separate layers may indicate varied function they all appeared to be invested by the same nerve - implying that they are activated together and isolation is not a realistic expectation in practice.
Conclusions	Cadaver dissection within this study suggests the presence of superficial and deep fibers of the gluteus maximus. The deep layer that only crosses the SIJ has facial connections to the pelvic floor and may contribute to pelvic girdle stability.
Conclusions of the Researchers	The 3 sub-components of the gluteus maximus do not appear to be separate muscles as they all seem to share the same nerve supply. The fibers that cross the SIJ and attach to the pelvic floor muscles may assist in pelvic girdle stability through co-contraction. Clinical use of these findings requires further investigation.

Note the thickness of the Gluteus Maximus in this Sagittal Section - https://upload.wikimedia.org/wikipedia/commons/b/b7/Gray344.png

Review & Commentary:

Why is this study important?

Cadaver dissection provides information on the insertions of muscles fibers which indicate the effect that muscle has on the joint(s) it crosses. The findings of this study indicate deep fibers of the gluteus maximus that only cross the SIJ and invest in the pelvic floor; these fibers likely contribute to pelvic girdle stability via force closure and not hip motion.

How does it affect practice?

Low back pain is a very common complaint and may be related to a loss of stability in the pelvic girdle that leads to improper biomechanics. That loss of stability can be attributed to a loss of strength, endurance, and/or timing of core stabilizers (which now may include the deep sacral fibers of the gluteus maximus). With proper activation exercises, stability of the pelvic girdle can improve with associated decreases in pain. Further research and investigation is required to determine if the deep fibers of the gluteus maximus activate with other core stabilizers or if it will require a different, more specific activation techniques.

How does it relate to Brookbush Institute Content?

The relationship between the gluteus maximus, the pelvic girdle, and the SIJ requires significant attention as pelvic instability and muscle imbalance leads to postural dysfunction and movement impairment in the lumbo-pelvic hip complex (LPHCD). This study may reinforce the idea that the gluteus maximus activation exercises already included in the corrective exercise strategies recommended are imperative to optimal intervention, and further reinforces the hyposthesized arthorkinematic dysfunction that is the result of, or potentially a cause of this compensation pattern. Further, it is possible that with contraction of the pelvic floor, the deep sacral fibers of the gluteus maximus co-contract to enhance stability. If so, then pelvic floor training, is of high importance in any LPHCD, and will need further attention in Brookbush Institute content. It is possible that deep fibers connecting to the multifidi apponeurosis will co-contract with activation of lumbar/sacral multifidi . Additionally, core activation exercises may produce a co-contraction of transverse abdominis (TVA), multifidi, pelvic floor muscles, and the deep sacral fibers of the gluteus maximus.

Gluteus Maximus: Superficial and Deep Fibers

Research Review: Gluteus Maximus: Superficial & Deep Fibers

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