Starting in the spinal cord trace a motor pathway to the add

Starting in the spinal cord, trace a motor pathway to the adductor muscles of the thigh, include the spinal cord root, spinal nerve, nerve plexus, and specific peripheral nerve involved in the pathway. Compare the types of neurons that synapse in the posterior, lateral, and anterior gray horns of the spinal cord.

Solution

Answer:

1. The obturator nerve is formed by the anterior divisions of the second, third and fourth lumbar nerves.

(a) It descends through the fibres of the psoas majormuscle and emerges from the medial border near the brim of the pelvis.

(b)Then it passes behind the common iliac arteries, and on the lateral side of the internal iliac artery and ureter.

(c) It runs along the lateral wall of lesser pelvis above the obturator vessels and to the upper part of the obturator foramen.

(d) Then it enters the thigh through the obturator canal, and divides into an anterior and a posterior branch. This is separated first by some of the fibers of the obturator externus, and lower down by the adductor brevis.

2. Posterior horn of spinal cord consists of sensory neurons, lateral horn of spinal cord, having well-defined thoracic segments, consist of visceral neurons and anterior horn of spinal cord consists of motor neurons.

Sensory neurons are those which receive information from sense organs, and then transmit it to visceral neurons, which act as intermediate neurons. From these neurons, the signals are relayed to motor neurons, which then pass the signal to motor cells to perform the relevant action as a response to the stimuli sensed.