In the central nervous system, there are three different layers that cover the spinal cord and brain. These are called the meninges, and their three levels consist of the: pia, arachnoid, and dura mater. Bone is situated above these layers, followed by periosteum (a fibrous membrane that covers bone) and skin.The dura mater is the top layer of the meninges, lying beneath the bone tissue.This material at times opens into sinus cavities (spaces) located around the skull.he dura mater is the top layer of the meninges, lying beneath the bone tissue. This material at times opens into sinus cavities (spaces) located around the skull.
Planet Earth Making Mountains Planet Earth filmmakers came out in the rugged mountains of Nepal in hopes of filming the elusive snow leopard for the Mountains episode. 01:51.
Domestic Production and Use: Rare earths were mined by one U.S. company in 2013. fluorocarbonate mineral, was mined as a primary product at Mountain Pass, CA. oxide mineral concentrate in 2013 was estimated to be 4,000 tons in 2013. percent of the rare-earth elements in the Mountain Pass bastnasite ore.