A dynamic electromyographic analysis of grasp and release, performed on
forty-eight upper extremities of forty-two adults who had had injury to the
brain causing spasticity, showed volitional motor control of the finger
flexors in 80 per cent and active extension of the fingers in 60 per cent.
The flexor pollicis longus showed volitional control in 75 per cent of the
hands and the extensor pollicis longus showed active control in 50 per
cent. The extensor carpi radialis longus acted as an appropriate stabilizer
of the wrist in 85 per cent of the extremities. Fourteen muscles had
out-of-phase activity that could not be detected on clinical examination.
The position of the elbow did not appreciably influence the
electromyographic pattern of motor control in the hand.