No abstract

Both superficial and deep laminae of the posterior layer are more extensive superiorly than previously thought. This may have implications for certain tests used in assessment and management of low back pain such as the slump and "nonorganic" tests. The thickness of the superior attachments is variable. Their capacity for load bearing is yet to be quantified.

Low levels of tension are effectively transmitted between TrA and the MLF or PLF. Via them, TrA may influence intersegmental movement.

Tension on the lumbar fasciae simulating moderate contraction of TrA affects segmental stiffness, particularly toward the neutral zone.

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.

The anatomy of the middle layer of lumbar fascia (MLF) is of biomechanical interest and potential clinical relevance, yet it has been inconsistently described. Avulsion fractures of the lumbar transverse processes (LxTP's) are traditionally attributed to traction from psoas major or quadratus lumborum (QL), rather than transversus abdominis (TrA) acting via the MLF. This attachment is also absent from many biomechanical models of segmental control. The aims of this study were to document: (1) the morphology and attachments of the MLF and (2) the attachments of psoas and QL to the LxTP's. Eighteen embalmed cadavers were dissected, measuring the thickness, fibre angle and width of the MLF and documenting the attachments of MLF, psoas and QL. The MLF was thicker at the level of the LxTP's than between them (mean 0.62: 0.40 mm). Psoas attached to the anteromedial surface of each process and QL and TrA to its lateral border; QL at its upper and lower corners and TrA (via the MLF) to its tip. In three cadavers, tension applied to the MLF fractured a transverse process. The MLF has a substantial and thickened attachment to the tips of the LxTP's which supports the involvement of TrA in lumbar segmental control and/ or avulsion fracture of the LxTP's.

The objectives of this study were to investigate the anatomical relationship between the proximal adductor longus (AL) and rectus abdominis muscles and to determine whether unilateral loading of AL results in strain transmission across the anterior pubic symphysis to the contralateral distal rectus sheath. Bilateral dissections were conducted on 10 embalmed cadavers. Strain transfer across the pubic symphysis was examined on seven of these cadavers. An AL contraction was simulated by applying a controlled load in the direction of its proximal tendinous fibers, and the resultant strain in the contralateral distal rectus sheath was measured using a foil-type surface mounted microstrain gage. Adductor longus attached to the antero-inferior aspect of the pubis. In 18 of the 20 limbs, the proximal attachment of AL was tendinous on its superficial surface and muscular on its deep surface. The proximal AL tendon was found in most instances to have secondary communications with structures such as the contralateral distal rectus sheath, pubic symphysis anterior capsule, ilio-inguinal ligament, and contralateral proximal AL tendon. Despite these consistent anatomical observations, strain measured in the contralateral distal rectus sheath upon unilateral loading of the proximal AL varied considerably between cadavers. Measured strain had an average ± 1SD of 0.23 ± 0.43%. The proximal attachment of AL contributes to an anatomical pathway across the anterior pubic symphysis that is likely required to withstand the transmission of large forces during multidirectional athletic activities. This anatomical relationship may be a relevant factor in explaining the apparent vulnerability of the AL and rectus abdominis attachments to injury.

Chronic groin pain is a common complaint for athletes participating in sports that involve repetitive sprinting, kicking or twisting movements, such as Australian Rules football, soccer and ice hockey. It is frequently a multifactorial condition that presents a considerable challenge for the treating sports medicine practitioner. To better understand the pathogenesis of chronic groin pain in athletes, a precise anatomical knowledge of the pubic symphysis and surrounding soft tissues is required. Several alternative descriptions of pubic region structures have been proposed. Traditionally, chronic groin pain in athletes has been described in terms of discrete pathology requiring specific intervention. While this clinical reasoning may apply in some cases, a review of anatomical findings indicates the possibility of multiple pathologies coexisting in athletes with chronic groin pain. An appreciation of these alternative descriptions may assist sports medicine practitioners with diagnostic and clinical decision-making processes. The purpose of this literature review is to reappraise the anatomy of the pubic region, considering findings from cadaveric dissection and histology studies, as well as those from diagnostic imaging studies in athletes.