Exploring the Dorsal Scapular Nerve

By Whitney Lowe
[Science of Nerves]

Nerves are particularly vulnerable to compression and tension problems when they pass through narrow tunnels, between closely adjacent structures, or directly through soft tissues. The dorsal scapular nerve (DSN) has a number of sites vulnerable to compression and tension pathology along its path, so let’s take a look at where they are and what symptoms they can produce in your clients.  
The DSN originates from the C5 nerve root along with other nerve fibers that eventually make up the major trunks of the brachial plexus. While the majority of brachial plexus fibers course between the anterior and middle scalene muscles, the DSN goes directly through the middle scalene muscle and then curves around the posterior scalene muscle before heading in a posterior direction toward the upper back region (Images 1 and 2).
After curving around the posterior scalene muscle, the DSN descends along the medial border of the scapula. On its way along the medial border of the scapula, it gives out branches to innervate the levator scapulae muscle as well as the rhomboid major and minor. The DSN is a motor nerve, so it is not carrying any significant number of sensory fibers. However, as we will see later, pressure on this nerve can still produce painful sensations even if it is only a motor nerve.

Potential Causes of DSN Neuropathy
The DSN is susceptible to both compression and tension pathologies at different points along its path. Because it is primarily a motor nerve, the main symptoms from nerve compression or tension are atrophy and weakness of the muscles supplied by the nerve (rhomboids and levator scapulae). The most notable clinical sign that occurs from this nerve signal interruption is winging of the scapula. However, pain in the upper back, shoulders, or arms could also occur as a result of compression or tension pathologies affecting the nerve.
Pain in the upper back between the scapulae is one of the most common complaints for clients seeking pain relief through massage treatment. A number of researchers and clinicians are now suggesting that entrapment or impairment of the DSN may be a much more common factor in causing those sensations than previously thought.
There are three primary causes of DSN neuropathy: middle scalene nerve entrapment, small nerve branch compression, and dysfunctional feedback loop.1

Entrapment of the Nerve by the Middle Scalene Muscle
The first primary cause of DSN neuropathy is entrapment of the nerve by the middle scalene muscle. The scalene muscles are routinely implicated in nerve compression problems in variations of thoracic outlet syndrome. However, as mentioned earlier, the DSN actually goes through the middle scalene muscle instead of between the middle and anterior scalene muscles. The nerve can become entrapped when the muscle is enlarged (called muscular hypertrophy). In some cases, fibrous bands may run through the muscle, and the rigid edge of these fibrous bands may compress the sensitive nerve.
Because the DSN is a motor nerve, neuropathy (pathology of the nerve) most commonly produces muscle weakness or atrophy. It would therefore seem odd that pain would be a primary symptom of nerve compression since this nerve does not carry a significant number of sensory fibers. This brings up an interesting anatomical factor regarding neural anatomy. There are actually very small nerve fibers that innervate the outer sheath of any nerve. Essentially, this is sensory nerve supply to the nerve itself. The small fibers that innervate the outer sheath of the nerve are called the nervi nervorum.
The nervi nervorum fibers are sensitive to both compression and stretching of the nerve. One of the common complaints from those experiencing DSN pathology is pain when performing overhead activities with the arm. Because of shoulder mechanics and the pathway of this nerve, it is likely that the DSN nerve is getting stretched during these activities. In addition, if there is even a slight degree of compression on the nerve, stretching or pulling the nerve fibers taut could aggravate the compressive force.
When you do activities that either stretch or compress the nerve, you are reinforcing those signals of irritation to the central nervous system. The more those signals get reinforced, the less it takes to set them off, which can lead to perpetual and chronic pain and irritation of the DSN and the muscles it innervates.
One anatomical study found a communicating branch between the DSN and the long thoracic nerve, which innervates the serratus anterior muscle and can also be implicated in scapular winging when it is compressed.2 This connecting branch between the two adjacent nerves will increase the likelihood that nerve compression or tension sensations would be felt in areas innervated by either of those two nerves.

Compression of Small Nerve Branches
The second possible cause of DSN pathology is compression of any of the small branches of the nerve by taut bands of muscle in the upper thoracic region. Myofascial trigger points are frequently associated with these taut bands and muscle tightness that constricts the small branches of the nerve, that may then cause mid-thoracic and medial scapular border pain (along the path of the DSN). The symptoms of nerve compression, whether from taut bands of muscle in the mid-thoracic region or by the middle scalene muscle, could be identical and difficult to distinguish. For that reason, any comprehensive treatment aimed at addressing potential nerve compression in this area should thoroughly address the cervical, shoulder, and upper-back regions.

Dysfunctional Feedback Loop
The third major contributing factor to DSN pathology is a dysfunctional feedback loop that happens with muscular weakness. Compression of the nerve interrupts motor signals and causes weakness and atrophy in the levator scapulae and rhomboid muscles. As noted earlier, the most prominent clinical indicator of this motor impairment is winging of the scapula.
When the scapula pulls away from the thoracic rib cage in the scapular winging dysfunction, the medial border lifts up in a lateral direction away from the spine during certain movements. As the bone moves out in this position, it pulls on the skin and superficial cutaneous nerves of the upper-back region. These superficial nerves innervating the skin can produce mid-thoracic back pain simply because they are being tugged on. In this case, upper-back pain can be caused both by compression of the DSN as well as tension or tugging on the superficial cutaneous nerves of the upper back.
The tugging or tensile forces applied to these superficial cutaneous nerves can also be aggravated in certain postural distortions. Individuals with upper thoracic kyphosis or forward-head posture and forward-rounded shoulders already have increased tensile loads across the upper back’s superficial tissues. All these factors can combine to produce pain and irritation in the upper-back region. Most likely, any one of these factors alone may not produce a significant problem. It is often the compounding of these factors together that may create the pain and impairment.

Other Causes of DSN Neuropathy
While not common, there are some other potential causes of DSN injury that can lead to muscle weakness or pain. Myofascial trigger points are frequently described as occurring in the upper-thoracic region, and trigger point injection and dry needling have both been used as treatment approaches to address this pain. Damage of the nerve has been reported from trigger point injections, dry needling, and nerve block injections in the scalene region.3
The pathway of the DSN is very close to that of the long thoracic nerve. There is a fair amount of literature describing pathological factors that lead to long thoracic nerve pathology. One of the common factors is heavy straps worn across the top of the shoulders, such as that from bras, backpacks, handbags, or heavy equipment bags. If your client is reporting any type of heavy strap or weight worn across the shoulder, that is a likely factor in the development of the nerve compression problem. In addition, any occupational or recreational activities they frequently engage in that involve extensive overhead movements of the upper extremity may contribute to neural compression or tension (and subsequent symptom production).
All branches of the brachial plexus, as well as the long thoracic and dorsal scapular nerves, are susceptible to overstretch and symptom production in rapid lateral whiplash injuries where the head is rapidly moved to one side. This occurs frequently in side-impact automobile accidents and may also occur in contact sports or other high-velocity movement encounters.
When taking a thorough history, identify any factors that might cause these kinds of biomechanical forces in the cervical region, as they could easily contribute to nerve compression pathology that produces pain in the neck or upper-back region.

Identifying Nerve Compression
It is difficult to accurately isolate DSN pathology. The best strategy involves looking for key factors in the client’s history, along with potential issues found in physical examination, such as mid-scapular pain, symptom aggravation with reaching overhead, or external loads that could be applying compression or tension to the affected nerve. In a study on DSN entrapment, researchers looked at individuals who had pain between the scapula as a prominent complaint. They found that over 50 percent of those individuals had some evidence of potential dorsal scapular nerve entrapment, indicating the condition may not be anywhere near as rare as once thought.4
Scapular winging caused by DSN compression can be confirmed by having the client place their hands on their hips and then attempt to move the elbows backward (Image 3). When performing that maneuver, the scapula will often pull off the thoracic rib cage if the muscles innervated by the DSN or long thoracic nerve are weak.
There may also be weakness in arm elevation, along with pain felt in the neck, shoulder, or arm during shoulder elevation or reaching overhead. Sometimes rotational movements in the cervical region may cause symptom aggravation if the rotary movement tugs on, or compresses, the affected nerve.
DSN compression pathology may also be a causative factor in other conditions of shoulder pain or dysfunction. If the scapular stabilizers are not working properly, this can adversely affect shoulder mechanics and can lead to other biomechanical challenges in the shoulder, such as impingement problems or rotator cuff pathology. The symptoms of these other problems are similar to DSN pathology, so they can sometimes be mistaken for each other. Be cautious about making assumptions in the causes of shoulder, neck, or arm pain; it’s not always simple.

Pain between the scapulae in the upper back is generally attributed to tight or overstretched muscles in the upper-back region. However, the existence of dorsal scapular nerve irritation causing the same symptoms may be more common than previously thought.
While we have yet to see any specific research on massage treatment for this problem, there are several treatment strategies that would seem helpful for addressing DSN pathology. Whenever possible, it is important to match the physiology of the tissue dysfunction with the primary effects of the treatment.
We noted earlier that there are three primary causes of DSN pathology. The first involves potential nerve compression in the cervical region where the nerve actually perforates the middle scalene muscle and curves around the posterior scalene before making its way into the upper-thoracic and mid-scapular region. Thus, hypertonicity in the scalene muscles may contribute to nerve compression producing the upper-back pain. Gentle pulling and applying longitudinal traction to the scalene muscles without pressing hard into them can often reduce their tightness (Image 4). They are close to the skin at this point, so it doesn’t take much pressure to produce beneficial therapeutic results.
The second potential cause of DSN pathology involves localized areas of tightness in the upper-back muscles and potential myofascial trigger points that may constrict small branches of the nerve. There are numerous treatment techniques that can be helpful in reducing tightness in the upper back, such as static compression, broad cross-fiber methods, stretching, and deep longitudinal stripping methods. A broad contact surface can be used for more general applications, and if there are small, localized areas of tightness, a small contact surface pressure can be used during these techniques (Image 5).
The third potential problem leading to DSN pathology is irritation of small cutaneous neural fibers between the scapulae as a result of scapular winging or postural challenges, such as upper-thoracic kyphosis and medially rotated shoulders. This variation affects the small cutaneous nerves the most, and addressing these seems most effective with light pressure, superficial skin stretching methods such as those described as myofascial release, or dermoneuromodulation. Place the hands on the upper back and stretch and pull the skin in various directions (no lotion or light lotion works best). More than likely, the client will feel a reduction in symptoms with one particular direction more so than others (Image 6). Once that direction is noted, simply pull the skin with light pressure in that direction and hold it for a minute or two.
In addition to any manual treatment techniques performed in the clinic, it will be very helpful to encourage the client to reinforce good posture and frequent movement to help mobilize the tissues. None of these strategies alone are likely to be the sole solution. More likely, you will find some unique combination of approaches that may work differently for each client. Also, there are many more techniques that could be used than those I briefly mention here. So, next time you have a client who comes in complaining of pain between the shoulder blades, consider the possibility of dorsal scapular nerve involvement as you take the history, go through your physical examination, and design their ideal treatment plan.   

1. H. E. Sultan and G. A. Younis El-Tantawi, “Role of Dorsal Scapular Nerve Entrapment in Unilateral Interscapular Pain,” Archives of Physical Medicine and Rehabilitation 94, no. 6 (2013): 1118–25, doi:10.1016/j.apmr.2012.11.040.
2. P. Shilal et al., “Aberrant Dual Origin of the Dorsal Scapular Nerve and its Communication with Long Thoracic Nerve: An Unusual Variation of the Brachial Plexus,” Journal of Clinical Diagnostic Research 9, no. 6 (2015): AD01–2, doi:10.7860/JCDR/2015/13620.6027.
3. D. G. Lee and M. C. Chang, “Dorsal Scapular Nerve Injury After Trigger Point Injection into the Rhomboid Major Muscle: A Case Report,” Journal of Back and Musculoskeletal Rehabilitation 1 (2017) : 1–4, doi:10.3233/BMR-169740; A. Saporito, “Dorsal Scapular Nerve Injury: A Complication of Ultrasound-Guided Interscalene Block,” British Journal of Anaesthesia 111, no. 5 (2013): 840–1, doi:10.1093/bja/aet358.
4. H. E. Sultan and G. A. Younis El-Tantawi, “Role of Dorsal Scapular Nerve Entrapment in Unilateral Interscapular Pain.”

Whitney Lowe is the developer and instructor of one of the profession’s most popular orthopedic massage training programs. His texts and programs have been used by professionals and schools for almost 30 years. Learn more at www.academyofclinicalmassage.com.