• Recall and explain the signs of lower motorneuron lesions.

LMN lesions - may show abnormalities such as decreased/absent reflexes, weakness, Atrophy of muscles and fasiculations. this is due to the fact that when the nerve is cut, its branches are cut off and so this results in the muscle that they once supplied no longer being inervated and so reflexes from the muscle cannot happen, atrophy (muscle wasting will occur) and fasiculations occur due to discharge from the now dormant skeletal muscle present in the space. (fasiculations are visible fast-spontaneous muscle contractions)

• 2. Recall and explain the signs of upper motorneuron lesions.

UMN lesions - usually the UMN’s are used to inhibit the reflex arc, however when the nerves become damaged they do the exact opposite which includes over stimulation of the muscle fibres, this can cause an increase in tone, increased reflexes, inc babinskis reflex (when the big toe points up and the rest of the toes fan out). weakness occurs and CLONUS can occur (especially in the ankle) CLONUS is the involuntary contraction of muscles.

• 3. Recall the changes seen in muscle after partial loss of its motor supply.

atrophy - LMN Fasiculations - LMN. Weakness - UMN/LMS.

Absent/decreased Reflexes - LMN

Tone increase - UMN CLONUS - UMN Weakness - UMN/LMN Increased reflexes - UMN

Babinski’s reflex - UMN

• 4. Explain the features reflecting partial denervation of muscle that may be visible in electromyographic recordings.

signs of denervation on an EMG include **the presence of fibrillation potentials, positive sharp waves, and increased insertional activity (**Increased insertional activity is generally considered as prolonged muscle membrane activity lasting more than 300 ms after theneedle movement stops)

A nerve conduction velocity between 50 and 60 meters per second is generally considered to be in the normal range.

(denervation is when nerves are damaged through any means)