The nervous system is a dynamic, interconnected system. Restriction in its ability to glide within the body in response to position changes increases the tension and susceptibility to compressive forces. Entrapment of a nerve at one site also makes it more susceptible to entrapment at other sites. Different nerves have multiple sites of potential entrapment with different movements and postures that contribute to the compression. This may be more related to stretch than compression.
Symptoms can be variable depending or the part of the plexus that is compressed.
It can result in numbness and weakness of the entire arm. The space the nerves pass through can become constricted due to tight muscles in the front of the neck from poor posture or use of scalene muscles for breathing which then also elevates the first rib. Forward shoulder posture allows the pectoralis minor muscle to tighten. The muscles in the front of neck are frequently strained in whiplash injuries. Activities that involve repetitive or sustained overhead use of arm, forward reaching, or excessive weight on the shoulder can cause symptoms.