The scalene muscles are key movement and positioning muscles and have significant clinical importance. I have already seen this first hand in clinic and worked to reduce hypertonicity in these muscles to relieve symptoms radiating into the upper extremity.
Anatomy of the Scalene Muscles.
There are 3 scalene muscles in either side of the anterior neck: the anterior scalene, the middle scalene and posterior scalene.
The anterior scalene arises from the anterior tubercles of the transverse processes of the C3 to C6 vertebrae and extends down the anterior neck to attach to scalene tubercle on the inner border of the first rib. It is innervated by the ventral rami of cervical nerves C5 to C7.
The middle scalene sits posterior to the anterior scalene and arises from the posterior tubercles of the TPs of C2 to C7, attaching to the upper surface of the first rib, behind the groove for the subclavian artery. It is innervated by the ventral rami of cervical nerves C3-C8.
The third of the scalene muscles, the posterior scalene arises from the posterior tubercles of the TPs of C5 to C7 and attaches to the outer surface of the second rib. The innervation of this muscle comes from the ventral rami of cervical nerves C7 and C8.
Primarily the scalenes are a muscle of breathing, elevating the upper ribs in deep inspiration but they also flex the neck when they act together. Individually they laterally flex and rotate the neck.
Of clinical interest, the brachial plexus and subclavian artery pass between the anterior and middle scalenes whilst the subclavian vein sits anterior to the anterior scalene. Tightness or spasm of the scalenes can cause compression on these structures contributing to Thoracic Outlet Syndrome, resulting in symptoms such as:
- numbness of whole arm and hand which can be constant or intermittent
- deep ache or pain into arms and/or shoulders
- pain can be worse in bed causing a disruption to sleep patterns
- feeling of the circulation to the arm being cut off
- if the circulation becomes restricted, the hands and fingers can become white and even blue and feel cold
- tight muscles in the neck can also lead to compression of the vertebrae making the neck stiff and difficult to tilt or rotate
- extreme tightness of the scalenes may also cause the upper ribs to be elevated affecting breathing
Luckily, treating tight scalenes is possible using manual techniques... but that's another post for another day!