( It ( ( ( spreads ( from ( ( infected ( mucosal surfaces ) ) ( -LRB- ( ( cervix ( , ( rectum ( , pharynx ) ) ) ) -RRB- ) ) ) ) ) ( ( ( ( to ( ( the ( small joints ) ) ( of ( ( ( ( ( ( ( ( ( ( the hands ) , ) wrists ) , ) elbows ) , ) knees ) , ) and ) ankles ) ) ) ) but ) rarely ) ( to ( axial ( skeletal joints ) ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ spreads) (PP (IN from) (NP (NP (JJ infected) (JJ mucosal) (NNS surfaces)) (PRN (-LRB- -LRB-) (NP (NN cervix) (, ,) (NN rectum) (, ,) (NN pharynx)) (-RRB- -RRB-)))) (PP (PP (TO to) (NP (NP (DT the) (JJ small) (NNS joints)) (PP (IN of) (NP (NP (DT the) (NNS hands)) (, ,) (NP (NNS wrists)) (, ,) (NP (NNS elbows)) (, ,) (NP (NNS knees)) (, ,) (CC and) (NP (NNS ankles)))))) (CC but) (ADVP (RB rarely)) (PP (TO to) (NP (JJ axial) (JJ skeletal) (NNS joints))))) (. .)))
It spreads from infected mucosal surfaces (cervix, rectum, pharynx) to the small joints of the hands, wrists, elbows, knees, and ankles but rarely to axial skeletal joints.
(ROOT (S (NP (NNS Knees) (CC and) (NNS elbows)) (VP (VBP are) (NP (NP (NNS examples)) (PP (IN of) (NP (NP (DT the) (NNS joints)) (PP (IN of) (NP (DT the) (JJ skeletal) (NN system))))))) (. .)))