The Meminges of the Brain & Spinal Cord

The brain and spinal cord are surounded by a series of three layers of modified connective tissue termed meninges. The outer layer or dura mater (also termed pachymenineges) is by far the toughest and is closely related to the surrounding bone of the cranium and the vertebral canal. The inner two layers, the arachnoid and the pia mater are closely related to each other and often viewed as a combonied layer termed the leptomeninges. Together these two layers house the cerebrospinal fluid, which acts a a waterjactet, surrounding and cushioning the central nerveous system tissue.