Hypertonicity vs spasticity

Hypertonicity or spastic dystonia

 1-hypertonicity or spastic dystonia is a continues increase in the muscle tension without regarding to the movement and is dependent upon afferent information from feedback following movements of stretch , decorticat and decerbrate rigidity are a form of spastic dystonia, spastic dystonia is considered to be a form of sustained efferent muscular hyperactivity , dependent on continues supraspinal derive to the alpha motor neuron

Spasticity

- spasticity is a velocity dependent increase in muscle tone in regarding to passive movement

pyramidal tract lesions

-pyramidal tract injury doesn't give raise to spasticity the main symptoms are weakness and loss of dexterity which is greater in distal than in the proximal muscles

 - pyramidal tract is the system which balance the muscle tone.

neural component of spasticity: 

1-Dorsoreticulospinal tract (DRT) : Has inhibitory effect on MRT &VST

2-medial reticulospinal tract (MRT) &

3-vestibulospinal tract ( VST ):

-they have facilitatory effect on the extensor tone,

- all the three systems are though to inhibit flexor reflex afferents responsible for flexor spasm