Question

Name the three meninges in which the spinal cord is sheathed as the brain.
A) Pia, arachnoid, and dura
B) Ventral root, white matter, and grey matter
C) Pia, ganglia, and ligament
D) Arachnoid, dura, and ligament

Answer 1

Hint: Meninges are the three membranes which envelop the brain and also the spinal cord. The main function of the meninges is to protect the central nervous system. The meninges are usually involved in cerebral pathology, as a common site of infection that causes meningitis and also intracranial bleeds.

Complete answer:
The major functions of meninges is to provide a supportive framework for the cerebral and cranial vasculature and also acts with cerebrospinal fluid to protect the central nervous system from any mechanical damage.

There are three layers of meninges which are known as the dura mater, arachnoid mater and pia mater. The dura mater is the outermost layer of the meninges and is situated directly below the bones of the skull and the vertebral column. The arachnoid mater is the middle layer of the meninges which lies below the dura mater. Below the arachnoid there is a space which is called the subarachnoid space that contains cerebrospinal fluid. The pia mater is located below the subarachnoid space.

Spinal cord is the connection center for the reflexes as well as for the afferent or sensory pathways and efferent or motor pathways for most of the body below the head and neck. Sensory neurons have the cell bodies in the spinal ganglion or dorsal root. Their axons travel through the dorsal root into the gray matter which contains the motor neurons whose axons travel out of the cord through the ventral root. The white matter surrounds the gray matter. Therefore, ventral root, white matter and grey matter are not the three meninges in which the spinal cord is sheathed as the brain.

The denticulate ligaments are bilateral triangular lateral extensions of pia mater that anchors the spinal cord to the dura mater. Hence the ligaments are not the meninges. So, option C is incorrect.
Arachnoid and dura are two of the meninges in which the spinal cord is sheathed as the brain, but ligament is not a meninges. Therefore, option D is incorrect.

Therefore, the correct answer is option ‘A’.

Note: Based on the location of meninges, they are referred to as the cranial meninges that envelop the brain, and spinal meninges which surround the spinal cord. However, the cranial and spinal meninges are continuous with each other and consist of the same three meningeal layers which are the pia, arachnoid, and dura mater.