( ( The ( arachnoid mater ) ) ( ( is ( one ( of ( ( ( the ( three meninges ) ) , ) ( ( the ( protective membranes ) ) ( that ( cover ( ( ( the brain ) and ) ( spinal cord ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (JJ arachnoid) (NN mater)) (VP (VBZ is) (NP (NP (CD one)) (PP (IN of) (NP (NP (DT the) (CD three) (NNS meninges)) (, ,) (NP (NP (DT the) (JJ protective) (NNS membranes)) (SBAR (WHNP (WDT that)) (S (VP (VBP cover) (NP (NP (DT the) (NN brain)) (CC and) (NP (JJ spinal) (NN cord))))))))))) (. .)))
The arachnoid mater is one of the three meninges, the protective membranes that cover the brain and spinal cord.
(ROOT (S (NP (NP (DT The) (CD three) (NNS layers)) (PP (IN of) (NP (NP (JJ protective) (NNS coverings)) (PP (IN of) (NP (DT the) (JJ spinal) (NN cord)))))) (VP (VBZ is) (VP (VBN called) (NP (DT the) (NNS meninges)))) (. .)))