what is the function of the arachnoid

Full Answer

What is the layer between the arachnoid and the pia?

The dura is a thick fibrous layer inside the surrounding bones, and the pia clings to the surface of the brain and spinal cord. Between them is the delicate arachnoid mater, which is connected to the pia by fine weblike strands. The cerebrospinal fluid lies between the arachnoid and the pia.

What is the subdural space?

The subdural space is also a potential space and may enlarge after head injury. The subarachnoid space between the arachnoid and pia contains cerebrospinal fluid and the blood vessels of the brain. The meningeal layer of dura continues into the vertebral canal as the dura mater covering the spinal cord.

What is the fluid that surrounds the brain?

The brain and spinal cord are suspended in a clear liquid called the cerebrospinal fluid (CSF). The CSF is contained by a tough membrane inside the skull and vertebral canal, called the dura mater. Thin elastic fibers, called the arachnoid, connect the dura mater to the pia mater, a thin membrane clinging to the surface of the brain and spinal cord. Because the brain is so soft and easily damaged, the cerebrospinal fluid plays an important protective role by acting as a shock absorber. The cerebrospinal fluid is manufactured inside the brain by networks of small arteries called choroid plexuses. The choroid plexuses are bound to adjacent ependymal cells, which line the inner surface of the ventricles. The cerebrospinal fluid flows from the lateral ventricles to the third ventricle, which is a narrow slit between the two halves of the hypothalamus. The fluid then travels along a narrow tube, called the aqueduct of the midbrain. The aqueduct drains into the fourth ventricle, which lies between the cerebellum and the brainstem. The fluid escapes through three holes in the roof of the fourth ventricle to fill the subarachnoid space. Cerebrospinal fluid is eventually reabsorbed into the blood circulation by specialized structures in the walls of large veins that line the inside of the skull.

What is the arachnoid mater?

The arachnoid mater, named for its spiderweb-like appearance, is a thin, transparent membrane surrounding the spinal cord like a loosely fitting sac. Continuous with the cerebral arachnoid above, it passes through the foramen magnum and descends caudally to the S2 vertebral level. It is closely applied to the inner surface ...

What is the pia mater?

The pia mater covers the surface of the brain dipping in between the gyri of the cerebral hemispheres and the folia (equivalent to gyri) of the cerebellum. It is comprised of two types of fibers – elastic and reticular, and is covered by cerebral vessels superficially in the subarachnoid space.

What is the term for the infection of the spinal cord?

When the spinal cord is also involved, the process is referred to as meningomyelitis.

What are the three layers of meninges?

The three layers of meninges (dura mater, arachnoid, and pia mater) that surround the brain also continuously envelop the spinal cord. The dura mater, a dense fibrous tissue extending distally to the S2 segment, is separated from the vertebral canal by an epidural fat layer and a venous plexus.