CHOROIDES is particularly used for the inner membrane which immediately invests the brain; so called as being intermingled with a great number of blood-vessels, like the chorion: but more usually denominated the pia mater or meninx tenuis.
Plexus or Lacis Choroides, is a knot of veins and arteries in the anterior ventricle of the brain, woven out of the branches of the carotid.