( ( ( skeletal ( , ( ( muscular and ) nervous ) ) ) systems ) ( ( are covered ) . ) )
(ROOT (S (NP (ADJP (JJ skeletal) (, ,) (JJ muscular) (CC and) (JJ nervous)) (NNS systems)) (VP (VBP are) (VP (VBN covered))) (. .)))
skeletal, muscular and nervous systems are covered.
(ROOT (S (ADVP (RB Together)) (, ,) (NP (DT the) (JJ muscular) (CC and) (JJ skeletal) (NNS organs)) (VP (VBP are) (VP (VBN known) (PP (IN as) (NP (DT the) (JJ musculoskeletal) (NN system))))) (. .)))
Together, the muscular and skeletal organs are known as the musculoskeletal system.