( ( By ( inhibiting ( the ( parasympathetic system ) ) ) ) ( , ( muscles ( relax . ) ) ) )
(ROOT (S (PP (IN By) (S (VP (VBG inhibiting) (NP (DT the) (JJ parasympathetic) (NN system))))) (, ,) (NP (NNS muscles)) (VP (VBP relax)) (. .)))
By inhibiting the parasympathetic system, muscles relax.
(ROOT (S (NP (DT The) (JJ parasympathetic) (NN system)) (VP (MD can) (ADVP (RB also)) (VP (VB be) (VP (VBN referred) (S (VP (TO to))) (PP (IN as) (NP (DT the) (JJ craniosacral) (NN system)))))) (. .)))