Reading XML Elements from behind code

How do I get the FirstName, LastName and OtherName on the below sample xml file? I need to assign them to a variable from behind code using C#.

  <PatientRecord>
      <Demographics>
              <Names>
                     <cdsd:LegalName namePurpose="L">
                               <cdsd:FirstName>
                                     <cdsd:Part>SARAH</cdsd:Part>
                                     <cdsd:PartType>GIV</cdsd:PartType>
                               </cdsd:FirstName>
                               <cdsd:LastName>
                                      <cdsd:Part>GOMEZ</cdsd:Part>
                                      <cdsd:PartType>FAMC</cdsd:PartType>
                               </cdsd:LastName>
                               <cdsd:OtherName>
                                       <cdsd:Part>GABRIELA</cdsd:Part>
                                       <cdsd:PartType>GIV</cdsd:PartType>
                               <cdsd:PartQualifier>BR</PartQualifier>