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 They sell the ramps for anywhere from $100 to $150 for suitcase ramps and $350 to $500 for travel ramps depending on the size. 2  Portable-Wheelchair-Ramps.com sells 2 to 6 feet ramps that are great for stairs, decks and vehicles. 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.