What are Meninges ?

The membranes of the craniosacral system include the dura mater (the "tough mother"), the arachnoid membrane, and the pia mater . Together, these membranes are called the meninges, which envelope the brain and spinal cord.

The outer layer of these membranes, the dura mater, is a tough relatively inelastic connective tissue which adheres to the inside surface of the skull bones. The dura forms 2 vertical structures called the falx cerebri and the falx cerebelli – each falx separates its associated portion of the brain, the cerebrum and the cerebellum, respectively. Relatively horizontal sheets, called the tentorium cerebelli, form bilaterally and separate the cerebellum from the cerebrum . The dura mater contains cerebrospinal fluid and forms the craniosacral hydraulic system. The slips of dura also connect to the second (possibly third) and the fifth cervical vertebrae in the neck, the second sacral segment, in the pelvis, and ends at the coccyx or tailbone.

The arachnoid membrane is thin, delicate, and has many blood vessels contained within it. This membrane is located between the dura and the pia maters, and is separated from them by spaces, above and below, which are filled with a fluid, called cerebrospinal fluid .

The pia mater is the innermost layer of membrane which is highly vascularized, follows the convolutions or folds of the brain and spinal cord, and delivers blood supply to these tissues.

The configurations of these meninges and the fluid provides for a degree of independent motion between the three membranes. The sliding motions (up to 2 cm.) allows the spine to rotate and bend without stressing the spinal cord.

Falx Cerebri	1
Falx Cerebelli	2
Tentorium Cerebelli	3
Diaphragma Sella	4
Superior Sagittal Sinus	5
Inferior Sagittal Sinus	6
Great Cerebral Vein	7
Straight Sinus	8
Confluence of the sinuses	9
Transverse Sinus	10

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