The thoracolumbar fascia completes fibrously the osteofibrous canal formed by the spine and the dorsal surfaces of the ribs.
Anatomy
The thoracolumbar fascia encloses the entire intrinsic back musculature and consists of three layers[^1].
Superficial lamina (posterior)
The superficial lamina is firmly connected to the aponeurosis of the erector spinae muscle in the sacral area. As it ascends, it becomes slightly thinner and serves as the origin for the latissimus dorsi and the serratus posterior inferior muscle. In the neck area, where it has already become thin, it separates the splenius capitis and splenius cervicis muscles from the trapezius and rhomboid muscles and continues into the nuchal fascia.
Deep lamina (anterior)
The deep lamina, originating from the costal processes of the lumbar vertebrae, separates the intrinsic back musculature from the ventrolateral abdominal wall musculature in the lumbar area. From the deep layer, reaching to the iliac crest, arise the oblique abdominal muscle and the transverse abdominal muscle.
Intermediate lamina
The intermediate lamina is located within the intrinsic back musculature and represents the topographical separation layer between the medial and lateral tracts.
Illustration
