Question

2. Why would a clinician test reflex function? Do hypoactive reflexes indicate damage within the CNS or PNS? Do hyperactive reflexes indicate damage within the CNS or PNS?

6. In regard to a knee jerk reflex test (if you can’t picture it, look it up on youtube) a. Which nerve is being evaluated? Which muscles contract? b. What action occurs at the knee joint? c. Describe, in detail, the nerve pathway involved in this reflex.

Answer 1

2.Reflex test are done by a clinician as it is important to diagnose the presence and location of spinal cord injury or neuromuscular disease.

Hypoactive reflexes are seen in injury or Damage in the PNS.

Hyporeflexia is Usually seen in Lower Motor Neuron Diseases(that is AHC/Nerve Root/Ganglion/Nerve/Neuromuscular Junction)

It occur usuallyas a result of damage to motor neurons.

Hyperreflexia is a Feature of Upper Motor Neuron (CNS)(From Cortex-------Anterior horn Cell of Spinal Cord)

Most common cause of Hyper reflexia:spinal cord injury.

2.Knee jerk Reflex or Patellar Reflex is sudden movement of the lower leg in response to a sharp tap on patellar tendon.

Pathway-

1.Tap in the Patellar tendon-----Activates Strech Receptors in the Quadriceps Femoris muscle.

2.This information is Carried by Sensory Neuron ---Dorsal Root ganglion---Spinal Cord

3.In the Spinal cord Sensory Neuron connect To Motor Neuron and Interneuron--Motor Neuron gets Activated.

4.This Motor Neuron Stimulates Quadriceps femoris to cause Contraction of Leg.

5.Inhibitor Interneuron synsapse with ventral horn Neurons that prevents its Contraction(which Cause Flexion-Opposite Action)

Nerve Being Evaluated :Femoral Nerve

Muscles Contracted:

Quadricpes Muscle Contracts to Cause Extension of Leg.(Biceps Femoris Relaxes)

Action at Knee joint:Extension