Studie som viser innervasjon av korsryggbindevev og påpeker at det er kun det ytre laget av bindevevet, det som er helt inn mot huden, som er tettpakket med sensoriske nerver og nociceptive fibre (som utskiller substans P og CGRP, og gir betennelser). De dypere lagene i midten av bindevevet eller ned mot musklene har nesten ingen nerveender eller sansesmuligheter.
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The subcutaneous tissue and the outer layer showed a particularly dense innervation with sensory fibers. SP-positive free nerve endings-which are assumed to be nociceptive-were exclusively found in these layers. Because of its dense sensory innervation, including presumably nociceptive fibers, the TLF may play an important role in low back pain.
Fig. 1. Structure of the rat thoracolumbar fascia (TLF) close to the spinous processes L4/L5. (a) Transversal section showing the three layers of the TLF (hematoxylin and eosin staining): OL, outer layer with transversely oriented collagen fibers; ML, middle layer composed of collagen fiber bundles oriented diagonally to the long axis of the body; IL, inner layer of loose connective tissue covering the multifidus muscle (muscle). SCT, subcutaneous tissue. (b) PGP 9.5-ir nerve fibers in the layers of the TLF. Black arrows, fibers on passage; open arrows, nerve endings. (c) Mean fiber length of PGP 9.5-ir fibers in the TLF. The great majority of all fibers were located in the outer layer (OL) of the fascia and in the subcutaneous tissue (SCT). White part of the bar: subcutaneous tissue plus outer layer of the TLF; black: middle layer; hatched: inner layer. n, number of sections evaluated.
Fig. 4. Distribution of CGRP and Substance P (SP)-immunoreactive nerve fibers in the TLF. (a) Mean fiber length of CGRP-ir nerve fibers. (b) Mean fiber length of SP-ir nerve fibers. Almost all fibers were found in the outer layer of the fascia and the subcutaneous tissue. The middle layer was free of SP-positive fibers. Gray part of the bars: subcutaneous tissue; white: outer layer of the TLF; black: middle layer; hatched: inner layer. n=number of sections evaluated. (c, d) Distribution of CGRP- (c) and SP-containing receptive free nerve endings (d) expressed as percent of the total number of CGRP- or SP-containing fibers in each layer. For classification as receptive endings, the structures had to exhibit at least three varicosities. SP-containing free nerve endings were restricted to the outer layer of the thoracolumbar fascia and the subcutaneous connective tissue while CGRP-containing free nerve endings were also found in the inner layer of the thoracolumbar fascia.
Og et bilde av de forskjellige bindevevslagene som er nevnt i denne studien.
Our study demonstrates that the rat TLF and the SCT overlying the fascia are densely innervated tissues, and therefore both the TLF and SCT, may play a role in low back pain. Most nerve fibers are located in the OL of the TLF and in the SCT, whereas in the ML nerve fibers are rare. Actually, no SP-ir fibers were found in this layer. Teleologically, the lack of fibers in the ML, particularly those containing SP, makes sense because each move- ment of the body causes shearing forces between the collagen fiber bundles, which might excite nociceptors.