Brain vessels enter the central nervous system through holes in the meningeal layers. The cells in the blood vessel walls are joined tightly to one another, forming the blood–brain barrier, which blocks the passage of many toxins and pathogens (though at the same time blocking antibodies and some drugs, thereby presenting special challenges in treatment of diseases of the brain). Neuroanatomists usually divide the vertebrate brain into six main regions: the telencephalon (cerebral hemispheres), diencephalon (thalamus and hypothalamus), mesencephalon (midbrain), cerebellum, pons, and medulla oblongata. Each of these areas has a complex internal structure. Some parts, such as the cerebral cortex
If We Are the Body Are the Body" live in concert. At a concert on April 1, 2005 at Giant Center in Hershey, Pennsylvania, the band opened up their set list with the song. At a concert on November 12, 2005 at the Stabler Arena in Bethlehem, Pennsylvania, they performed it as the third song on their set list. They performed the song at a concert held on March 22, 2008 at Jacksonville Veterans Memorial Arena in Jacksonville, Florida. Casting Crowns performed "If We Are the Body" as the second song on their set list at their February 4, 2010 concert at Sprint Center in