Interestingly, some of the newest research on nerve pain suggests that in fact it may be the small nerve fibers, such as the dorsal rami, that are a key to low back pain. Low back pain, while also potentially radiating down the lower extremity is often felt in the muscles and other tissues closest to the spine, which ironically are not innervated by fibers from the ventral nerve branches. 

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The dorsal rami (Image 1) are smaller nerve branches that come off the posterior aspect of the nerve root and are less vulnerable to disc compression than the ventral branches because of the location of the disc. The dorsal rami are called ‘mixed nerves’ because they carry both motor and sensory fibers. The motor fibers innervate the paraspinal muscles such as the three divisions of the erector spinae group, as well as the smaller intrinsic muscles like the multifidus. Sensory fibers from the dorsal rami supply the skin along the spine, as well as deep connective tissues of the vertebrae such as the posterior longitudinal ligament. While very small, the dorsal rami of spinal nerves can still carry up to 200,000 nerve fibers so there is still a great deal to be affected when these nerves are subjected to increased compression or tension.(Tubbs et al. 2015)

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Because they are very short, the dorsal rami don’t travel through any major tunnels or have nearby anatomical obstructions that often impact other nerves. However, that doesn’t mean they can’t be bound, restricted, or pulled. Many people report pain in their paraspinal muscles that is aggravated with additional pressure or stretching. It is likely that sensory fibers of the dorsal rami may be aggravated in many of these complaints. 

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Massage therapists help people with paraspinal muscle pain by using long gliding strokes along the length of the muscles. This treatment helps reduce muscle tightness and increases blood flow to superficial capillaries and tissues that experience ischemia. Gentle approaches, such as those used in myofascial release techniques, apply traction to the skin, which decreases tensile forces on the dorsal rami nerve fibers. Taking tension off the fibers helps reduce the noxious signals sent back to the central nervous system and can greatly reduce back pain. 

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Next time you are working on a client’s paraspinal muscles, try visualizing the location of the dorsal rami and consider how your massage techniques may be used to the greatest advantage in helping them function more effectively. 

 

Inferior, Medial, & Superior Cluneal Nerves

In the last issue we explored some of the nerves of the pelvic region that may be involved in gluteal pain problems and the role of the piriformis muscle. Piriformis syndrome is most commonly suspected when a person has serious gluteal pain. Yet, there is another set of superficial sensory nerves that innervate the gluteal region and should also be considered for gluteal pain – the inferior, medial, and superior cluneal nerves.

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The cluneal nerves innervate superficial tissues in the entire gluteal region, yet they are rarely mentioned in references on pelvic or low back pain. It is likely that you haven’t even heard of them. The cluneal nerves are sensory, not motor, and are divided into three branches: inferior, medial, and superior (image 2). The inferior division branches off the posterior femoral cutaneous nerve (PFCN). As a result, it could be affected by piriformis compression of the PFCN, which was discussed in the last issue.