Question

The sensory and motor tracts in the spinal cord are

	a.	Ipsilateral
	b.	Contralateral
	c.	Both a and b are correct
	d.	None of the above is correct

Answer 1

OPTION C -Both a and b are correct

REASON

The main sensory tract in our body are

1)Posterior column tract : It is a sensory tract that carry sensation like fine touch , vibration,propioception, to the spinal cord through the sensory nerves .

These fibers enter the spinal cord through the posterior rami and synapse in the posterior horn cell.From there , it is ascended through the posterior column of the spinal cord to the medulla.

In the medulla it decussate to the opposite side and ascend upward into the thalamus.from the thalamus it is ascended to the somatosensory cortex of cerebrum

So, a injury to the posterior coloumn in the spinal cord will lead to Ipsilateral loss of sensation because the fibres are only decussated in themedulla.

2)spinothalamic tarct: it carry sensation like crude touch ,pain, temperature into the brain through the spianl cord

The fibers of the spinothalamic tract are decussated from the spinal cord itself. so , the injury to the spinal cord produce controlateral loss.

MOTOR TRACT:

Pyramidal tract is the main motor tract in our body.

It is descending tract, descend from the motor cortex------->internal capsule--->thalamus----->pons------> medulla(in the medulla 85% of the fibre will decussate to the other side and 15% fibers will continue in the same side.

So, the injury to the spinal cord produce both controlateral and ipsilateral motor weakness.

Ipsilateral motor weakness will be more , because 85% fibers are decussated .