Meninges

Brain layers

Acta Eruditorum - IV fisiologia, 1703 – BEIC 13363829

Meninges are the three layers of protective tissue called the dura mater, arachnoid mater, and pia mater that encase the brain and spinal cord of the central nervous system. These membranes provide protection from injury, contain cerebrospinal fluid (CSF) that cushions the brain and spinal cord, and serve as a framework for blood vessels.

Structure

The meninges consist of three layers, each with distinct functions and characteristics:

• Dura Mater: The outermost layer is the dura mater, which is tough and durable. It is composed of two layers itself – the periosteal layer, which is attached to the skull, and the meningeal layer, which lies closer to the brain. The dura mater forms several structures that compartmentalize the brain and support large venous channels called dural venous sinuses.

• Arachnoid Mater: The middle layer is the arachnoid mater. This web-like layer is named for its appearance and is situated between the dura and pia mater. The arachnoid mater contains the subarachnoid space, which is filled with cerebrospinal fluid and contains blood vessels. The CSF in this space provides a cushioning effect for the brain and spinal cord.

• Pia Mater: The innermost layer is the pia mater, which is a thin, delicate membrane that closely adheres to the surface of the brain and spinal cord, following their contours. The pia mater contains many tiny blood vessels that nourish the brain and spinal cord.

Function

The primary function of the meninges is to protect the central nervous system. The dura mater provides a tough protective layer, the arachnoid mater allows for the flow of CSF, which cushions the brain and spinal cord, and the pia mater ensures that the brain and spinal cord receive necessary nutrients and oxygen from the blood.

Clinical Significance

1. 1. 1. Meningitis

Meningitis is an inflammation of the meninges, usually caused by infection. Symptoms can include headache, fever, and a stiff neck. It is a serious condition that can lead to severe health complications or death if not treated promptly.

1. 1. 1. Meningeal Carcinomatosis

Meningeal carcinomatosis is a condition where cancer cells spread to the meninges from another part of the body. This can lead to various neurological symptoms, depending on which areas of the brain or spinal cord are affected.

1. 1. 1. Subdural Hematoma

A subdural hematoma is a collection of blood between the dura mater and the arachnoid mater, usually due to a head injury. It can increase pressure on the brain, leading to symptoms such as headache, confusion, and drowsiness.

See Also

• Brain
• Spinal cord
• Cerebrospinal fluid
• Central nervous system