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.
Planet Earth is a 2006 British television series produced by the BBC Natural History Unit.Five years in the making, it was the most expensive nature documentary series ever commissioned by the BBC and also the first to be filmed in high definition.Planet Earth premiered on 5 March 2006 in the United Kingdom on BBC One.It had been shown in 130 countries worldwide by June 2007.Its first broadcast in the United States was on 25 March 2007 on the Discovery Channel, with Sigourney Weaver replacing David Attenborough's original commentary.lanet Earth premiered on 5 March 2006 in the United Kingdom on BBC One. It had been shown in 130 countries worldwide by June 2007. Its first broadcast in the United States was on 25 March 2007 on the Discovery Channel, with Sigourney Weaver replacing David Attenborough's original commentary.