A description of the lumbar interfascial triangle and its relation with the lateral raphe: anatomical constituents of load transfer through the lateral margin of the thoracolumbar fascia

Abstract

Movement and stability of the lumbosacral region is contingent on the balance of forces distributed through the myofascial planes associated with the thoracolumbar fascia (TLF). This structure is located at the common intersection of several extremity muscles (e.g. latissimus dorsi and gluteus maximus), as well as hypaxial (e.g. ventral trunk muscles) and epaxial (paraspinal) muscles. The mechanical properties of the fascial constituents establish the parameters guiding the dynamic interaction of muscle groups that stabilize the lumbosacral spine. Understanding the construction of this complex myofascial junction is fundamental to biomechanical analysis and implementation of effective rehabilitation in individuals with low back and pelvic girdle pain. Therefore, the main objectives of this study were to describe the anatomy of the lateral margin of the TLF, and specifically the interface between the fascial sheath surrounding the paraspinal muscles and the aponeurosis of the transversus abdominis (TA) and internal oblique (IO) muscles. The lateral margin of the TLF was exposed via serial reduction dissections from anterior and posterior approaches. Axial sections (cadaveric and magnetic resonance imaging) were examined to characterize the region between the TA and IO aponeurosis and the paraspinal muscles. It is confirmed that the paraspinal muscles are enveloped by a continuous paraspinal retinacular sheath (PRS), formed by the deep lamina of the posterior layer of the TLF. The PRS extends from the spinous process to transverse process, and is distinct from both the superficial lamina of the posterior layer and middle layer of the TLF. As the aponeurosis approaches the lateral border of the PRS, it appears to separate into two distinct laminae, which join the anterior and posterior walls of the PRS. This configuration creates a previously undescribed fat-filled lumbar interfascial triangle situated along the lateral border of the paraspinal muscles from the 12th rib to the iliac crest. This triangle results in the unification of different fascial sheaths along the lateral border of the TLF, creating a ridged-union of dense connective tissue that has been termed the lateral raphe (Spine, 9,1984, 163). This triangle may function in the distribution of laterally mediated tension to balance different viscoelastic moduli, along either the middle or posterior layers of the TLF.

Spread of Quadratus Lumborum Block to the Paravertebral Space Via Intramuscular Injection

“…The MLF contains the fascia of the QL, which surrounds aponeurotic abdominal muscles originating from the TA and the paraspinal retinacular sheath. 14,17 In our study, LA injection at our administration point revealed LA spread in various directions within the QL. However, LA spread only in compartments surrounding the ALF, MLF, and QL, with no contrast observed in the PVS.…”

“…The TLF is composed of anterior (ALF), middle (MLF), and posterior layers (PLF), which envelop the back muscles from the sacral region to the thoracic region. [18][19][20] As described by Schuenke et al, 14 the MLF and ALF are attached to the transverse process. The MLF contains the fascia of the QL, which surrounds aponeurotic abdominal muscles originating from the TA and the paraspinal retinacular sheath.…”

Quadratus Lumborum Block Versus Transversus Abdominis Plane Block for Postoperative Pain After Cesarean Delivery

“…1,2 This interfascial plane is in close relation with multiple sympathetic fibers and connects with the thoracic paravertebral space. It is also used by the posterior and lateral intercostal vessels to exit to the abdominal wall.…”

Posterior Branches of Lumbar Spinal Nerves - Part I: Anatomy and Functional Importance

“…Po więź pier sio wo -lę dźwio wa, ota czając głę bo kie i po wierz chow ne mię śnie grzbie tu i jedno cześnie po sia da jąc po łącze nie z mięśnia mi two rzą -cy mi ścia nę brzu cha, two rzy zwar tą struk tu rę w dolnej części tu ło wia, co ma istot ny wpływ na sta bi li zację lędźwio wo -krzyzȯwe go od cin ka kręgo słu pa [35]. supply, i.e.…”

“…The thoracolumbar fascia, which surrounds deep and superficial muscles of the back and is also connected to the muscles forming the abdominal wall, forms a compact structure in the lower trunk, which significantly contributes to lumbosacral spinal stability [35]. Deep muscles of the back control two-thirds of all intersegmental movements in the lumbar spine [36].…”