 While multiple muscles in a limb are usually affected in the upper motor neuron syndrome, there is usually an imbalance of activity, such that there is a stronger pull in one direction, such as into elbow flexion.Decreasing the degree of this imbalance is a common focus of muscle strengthening programs.Spastic movement disorders also typically feature a loss of stabilisation of an affected limb or the head from the trunk, so a thorough assessment requires this to be analysed as well.