Anatomy and biomechanics of gluteus maximus and the thoracolumbar fascia at the sacroiliac joint

Abstract

Biomechanical models predict that recruitment of gluteus maximus (GMax) will exert a compressive force across the sacroiliac joint (SIJ), yet this muscle requires morphologic assessment. The aims of this study were to document GMax's proximal attachments and assess their capacity to generate forces including compressive force at the SIJ. In 11 embalmed cadaver limbs, attachments of GMax crossing the SIJ were dissected and their fascicle orientation, length and attachment volume documented. The physiological cross-sectional area (PCSA) of each attachment was calculated along with its estimated maximum force at the SIJ and lumbar spine. GMax fascicles originated from the gluteus medius fascia, ilium, thoracolumbar fascia, erector spinae aponeurosis, sacrum, coccyx, dorsal sacroiliac and sacrotuberous ligaments in all specimens. Their mean fascicle orientation ranged from 32 to 45° below horizontal and mean length from 11 to 18 cm. The mean total PCSA of GMax was 26 cm(2) (range 16-36), of which 70% crossed the SIJ. The average maximum force predicted to be generated by GMax's total attachments crossing each SIJ was 891 N (range 572-1,215), of which 70% (702 N: range 450-1,009) could act perpendicular to the plane of the SIJ. The capacity of GMax to generate an extensor moment at lower lumbar segments was estimated at 4 Nm (range 2-9.5). GMax may generate compressive forces at the SIJ through its bony and fibrous attachments. These may assist effective load transfer between lower limbs and trunk.

Atrophy of gluteus maximus among women with a history of chronic low back pain

“…Gluteus maximus is more active during a wide stance lift, but only with heavier weights [51]. Gluteus maximus also has important proximal attachments to the thoracolumbar fascia, and may play a direct role in spinal extension through this attachment [52]. …”

Detailed spatial characterization of superficial hip muscle activation during walking: A multi-electrode surface EMG investigation of the gluteal region in healthy older adults

“…This resulted in a bilateral arrangement of eight vertically oriented bipolar channels (named P1 to P8 from the ventral to the dorsal margin) covering a horizontal distance of 17.5 cm. For this electrode arrangement, positions P1 and P2 represented TFL activity [29], positions P3 to P5 the Gmed [30], and the three dorsal positions P6 to P8 the Gmax [31, 32] with high certainty, whereas the electrode positions P1, P4/P5 (mean value), and P8 most closely represented the respective SENIAM positions. The anatomical relationship between these electrode positions and the respective muscles was further confirmed by own detailed studies of human cadaver specimens (S1 Fig).…”

The Treatment of Chronic Coccydynia and Postcoccygectomy Pain With Pelvic Floor Physical Therapy

“…For all patients, the first items addressed at each physical therapy session was lumbosacral posture and pelvic girdle bony symmetry; stretching and manual muscle energy techniques were used to bring the pelvis, sacrum, and lumbar spine into neutral alignment if required. Asymmetry of the pelvic girdle has been hypothesized to elicit gluteus maximus, levator ani, and lateral hip rotator muscle overactivity, which can affect both the sacroiliac joints and coccyx [21,22]. Each patient also was instructed in proper pelvic posture with sitting and standing to minimize pelvic floor muscle overactivity, as demonstrated by biofeedback recordings via surface electrodes.…”