Question

use the following information to answer question 3.
the achilles tendon reflex is observed when the achilles tendon of a person is tapped with a patellar hammer and the calf muscle contracts. a doctor tapped the achilles tendon of a man and did not observe a contraction of the mans calf muscle. the man reported that he felt the hammer strike his tendon.
the achilles tendon reflex pathway

1. the two structures numbered above that are most likely damaged in the achilles tendon reflex pathway are

a. 1 and 2
b. 1 and 3
c. 2 and 3
d. 3 and 4

Explanation:

1. The man felt the hammer strike, meaning the sensory pathway (structure 1: receptor, structure 2: sensory neuron) is functional, as these carry the touch signal to the brain.
2. No calf contraction means the motor pathway is damaged. Structure 3 is the interneuron/motor neuron origin in the spinal cord, and structure 4 is the motor neuron that signals the calf muscle to contract. Damage to these would prevent the reflex contraction while leaving sensation intact.

Answer:

D. 3 and 4