Lesions of cranial nerves IX, X, XI AND XII often occur together, frequently because of vascular disease affecting the medulla. The resultant palatal, pharyngeal and tongue weakness causing dysphonia, dysphagia and dysarthria is known as 'bulbar palsy'. Bilateral supra nuclear lesions affecting the pyramidal tracts (e.g. due to diffuse vascular disease, motor neuron disease, multiple sclerosis) cause loss of voluntary palatal and pharyngeal movements, but the gag reflex is preserved. The tongue is small (spastic) and shows poor rapid movement, this resulting in indistinct speech (spastic dysarthria). The jaw jerk is brisk. This state is known as 'pseudobulbar palsy'.