Dooley Noted: 11/23/2016
The scalenes are often a misunderstood and mistreated group of muscles with hugely impactful clinical importance.
The anterior scalene starts its course where its synergist, the longus colli, ends: at the anterior tubercles of transverse processes (TPs) of C4-C6. This muscle then anchors itself to the first rib.
The middle and posterior scalene often blend in fibers as one large mass of muscle, posterior to the middle scalene. If the bellies are discernible, then middle scalene will reach from C1-C3 anterior tubercles of TPs to the first rib. The posterior will start much like the anterior scalene but will end up on the second rib.
Due to their positions and fiber directions, these muscles concentrically work best as neck flexors and lateral flexors, when the rib is fixed.
If the neck is the fixed point of movement, they can easily be used as accessory muscles of respiration, raising the upper ribs.
These muscles must only be used as temporary muscles of respiration, since the decrease in thoracic pressure is minimized for inhalation if they are used to elevate the rib cage. Their eagerness can create abdominal stability problems, leaving the core musculature inactive and creating possible spinal stability problems.
Even more problematic is the overstretching of especially the anterior scalene.
As this muscle fixes into a locked long position, the client loses the ability to neck flex. As the extensors go unopposed, the result can be intense posterior neck muscle activation and subsequent headaches, scapulothoracic dysfunctions, and even migraines.
In the worst case scenario, the locked long scalenes can create neurovascular compromise. The subclavian artery, which feeds the entire upper extremity, is wedged between the anterior and middle scalenes. Posterior to the artery is the brachial plexus nerve roots and trunks, which innervate the entire upper extremity.
Thus, when the scalenes are mismanaged, particularly in a locked long position, they can stretch themselves right across this neurovascular bundle, potentially creating whole hand numbness and circulation impediments.
But it may not start off that dramatic.
The first sense usually to be lost is dorsal column-mediated in the spinal cord. The patient may lose vibration sense, which may or may not be recognized by the patient. Long before the patient experiences numbness, they may experience a quick change in proprioception (position sensing), which means the muscles lose perceived strength due to motor control insufficiencies.
This can be tested with “OK” grip testing at the hand, with median nerve and ulnar nerve supplying much of the thumb and pinky sides of grip, respectively.
If both the thumb side and pinky side of one hand only is diminished on testing, the person may be prone to scalene inhibition (stretch-weakening), leading to neuropathic signs.
The person will also have a stretched-out look to the neck and possible lateral flexion neck bias to the OPPOSITE side.
The person will have a tendency to have hypertonicity on both sides, but actually feel consistent discomfort on the stretched-out side (the same side as neuropathic symptoms).
The additional caveat as they may feel the need to stretch the neck on the already stretched side, exacerbating the stretch across the neurovascular bundle.
When testing grip, the test will likely improve upon coronally stretching the OPPOSITE side, which shortens the stretched-out side in this plane. This takes the stretch tension off the compressed neurovascular bundle, resulting in better circulation and nerve conduction.
If the person has whole-hand numbness, the numbness will likely dissipate upon lateral flexion to the side of issue, if the scalenes are the problem.
The scalenes are rarely locked bilaterally short at the neck. Even people with forward head carriage are typically righting the head to the horizon, taking the upper and mid-cervical segments into extension (an upper scalene stretch position).
However, the scalenes become bilaterally short at the rib when scalenes are used for quiet breathing. The symptoms include a tight, tense neck with loss of intra-abdominal pressure building. This can show up in cases from migraine to tension headache to low back pain.
Consider better movement coordination of the scalenes, and consider these observations before you administer manual stretch therapy to what may potentially be the wrong side.
As always, it’s your call.
– Dr. Kathy Dooley
P.S. Case Study Sample:
Active adult, age 29
Symptoms: neck tension on LEFT at TPs
C4-C6, no numbness
Signs: locked long left neck, locked short right neck in coronal plane
Testing: grip loss in both him and pinky with you OK testing on left hand only
Treatment: release of RIGHT side scalenes in coronal plane stretching resulted in return of grip power and motor control on thumb and pinky side of left grip.