[The respiratory movement of rib cage in relation to electromyographic activity of the biceps brachii muscle neurotized by the intercostal nerves].

The motor unit potentials of biceps brachii muscle innervated by intercostal nerves and those of second intercostal muscle in relation to respiratory cycle were studied by electromyography (EMG) in 23 patients with traumatic brachial plexus palsies. These patients were followed from about 2 years to 17 years averaging 5 years after intercostal nerves crossing to musculocutaneous nerve. The integrated EMG of biceps brachii muscle ranged from 4 muVS to 244 muVS per second during respiratory phase, with voluntary elbow flexion weighted 500 grams in the hand. Twelve cases showed no significant differences of integrated EMG of biceps brachii muscle between the inspiratory and the expiratory phase. Eleven cases exhibited a significant difference (p < 0.05) between the inspiratory and the expiratory phase. Four out of 11 cases displayed much more integrated EMG activities of biceps brachii muscle in the expiratory phase than those in the inspiratory phase; all these four showed excellent biceps brachii muscle strength. Departure of voluntary elbow movement from the respiratory cycles did not always give the biceps brachii muscle satisfactory strength and did not relate to the postoperative time after nerve surgery.