Disorders Of Muscle Tone

Question 1

Compare spasticity & rigidity with respect to cause & spinal motor neuron

Answer 1

S, UMNL, increased activity of gamma motor neuron
R, substantia nigra lesion, inc activity of alpha motor neuron

Question 2

Compare spasticity & rigidity with respect to affected muscles & resistance to movement

Answer 2

S, antigravity, unidirectional
R, all muscles ex extraocular, flexors more affected, bidirectional

Question 3

Mention causes of hypotonia

Answer 3

Cerebellar lesions
Chorea
Area 4 lesion
Inc serus Ca++
Acute UMNL
LMNL

Question 4

Compare decorticate & decerebrate rigidity with respect site, rubrospinal tract & motor neuron activity

Answer 4

Decorticate, upper midbrain above superior colliculus, intact, inc gamma motor activity
Decerebrate, lower mibrain between sup & inf colliculi, decreased, inc alpha & gamma motor neurons activity