Page 104 - Headlines Histology2024_Neat

Brain stem

• The brain stem comprises midbrain, medulla oblongata and pons.
• It consists of a mass of white matter that house the main sensory and motor

tract. In addition, clusters of neurons (nuclei) are also found within the
white matter.

Meninges

• It is a connective tissue layer that invests the outer surface of the brain and
spinal cord. It provides protection against traumatic forces.

Dura mater

• It is a dense fibro-elastic connective tissue layer lined on its internal surface
by mesothelium.

• It is separated from the underlying layer (arachnoid) by a subdural space,
containing minute amount of fluid.

• Around the spinal cord, the dural mater is suspended from the periostium of
the spinal canal by denticulate ligaments.

• The space between the dura and the overlying periostium is called epidural
space and is filled with loose connective tissue, fat and a venous plexus.

Arachnoid

• It consists of two components delicate connective tissue layer and arachnoid
trabeculae. The connective tissue layer is foemed of fine collagen fibers in
contact with the dura mater.

• The arachnoid trabeculae are thin strands of the membrane lined by
flattened fibroblasts look like spider web.

• The trabeculae traverse the subarachnoid space that is located between the
connective tissue layer and the pia mater. This space is filled with
cerebrospinal fluid.

• As vessels penetrate the CNS, an extension of the subarachnoid space
extends around the vessel forming perivascular space.

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