The meninges are three layers of connective tissue that surround both the brain and spinal cord to form a complete enclosure (Fig. 6-3) . The outermost of these membranes, the dura mater, is the thickest and toughest of the meninges.he meninges are three layers of connective tissue that surround both the brain and spinal cord to form a complete enclosure (Fig. 6-3) . The outermost of these membranes, the dura mater, is the thickest and toughest of the meninges.
These are generally made of wood, steel, or concrete. While concrete is the most durable, it is also the most expensive and the most difficult to install. Steel ramps are more durable than wooden ramps, though they tend to be heavier, more expensive, and heat up in the sun. Wooden ramps are the most aesthetically pleasing, but need to be weatherproofed and treated in order to last. Depending on the type of wood and other specifications, a permanent wheelchair ramp used to reach a height of 30 inches (30 feet long) can cost between $3,500 and $8,000, or between $100 and $250 per linear foot.
1 On average, a ramp can range anywhere from $50 to as much as $500 for the ramp itself. 2  This will not include the professional installation rates. 3  The minimum amount you should plan on spending is from $1,300 to as much as $3,000 to have the ramp built and installed. Each site offers a handsome discount for the product, which can help you save a few hundred dollars. 2  Wheelchair ramps vary in price because of the materials from which it is made. 3  More durable materials may cost more, but it will allow you to save in the long run since it will last longer.