Electromyographic study of sternocleidomastoid and scalene muscles in tetraplegic subjects during respiration.

An electromyographic investigation of inspiratory respiratory muscles was carried out in six tetraplegic and two normal subjects using needle electrodes. When the normal subjects were using tidal breathing there was no activity present. In the majority of tetraplegic subjects, activity was present in the scalene muscle during tidal breathing. This activity became more marked during deep inspiration. The muscles were hypertrophied and these muscles filled an important respiratory role.