All of the above (flexor contraction, extensor contraction, contraction of the
limbs and neck).
The rigidity in Parkinson’s disease involves both the flexor
and extensor musculature and often is particularly present in the limbs and neck.
Evaluation of the resistance to passive manipulation often appreciates the underlying
tremor, manifest as “cogwheeling.” This tone is not velocity dependent
like spasticity and is often most noticeable during slow passive movements.
