Question

Motor signals leave the spinal cord through the __________ roots, while sensory signals enter the spinal cord through the __________ roots.

• posterior; posterior

• anterior; anterior

• posterior; anterior

• anterior; posterior

Answer 1

MOTOR SIGNALS LEAVE THE SPINAL CORD THROUGH .................. ROOTS. WHILE SENSORY SIGNALS ENTER THE SPINAL CORD THROUGH ............... ROOTS.

From the question we can understand that ' we must find the nerve roots of motor signals and sensory signals.

NERVE ROOTS : A spinal nerve is a mixed nerve which carry motor ,sensory and autonomic signals between the spinal cord and the body.

our body has 31 pairs of spinal nerves one on each side of vertebral column.

spinal nerves arise from both sides of the spinal cord and emerge through intervertebral foramina .

each nerve is a union of motor (anterior) and sensory (posterior) nerve root , therefore it's a mixed nerve(spinal nerve ).

THE ANTERIOR NERVE ROOTS (ventral roots ) allow MOTOR NEURONS to exit the spinal cord.

THE POSTERIOR NERVE ROOT (dorsal root) allow SENSORY NEURONS TO ENTER THE SPINAL CORD.

Ventral roots - efferent motor root - carry information from brain .

while dorsal root carry sensory information (signals) to brain .

ANSWER :

SO we can understand from above that

motor signals leave spinal cord through the anterior root  .while sensory signals enter the spinal cord through posterior root..

the give options are

a) posterior, posterior.

b) anterior , anterior

c) posterior , anterior.

d) anterior , posterior .

THE ANSWER IS OPTION -(D)

This is because motor signals exit spinal cord through anterior roots ,while sensory signals enter spinal cord through posterior root.

Remaining options are given to confuse us. They are incorrect .

OPTION- a,b,c are given in order to confuse us .