A system for accessing a paranasal sinus cavity in the head of a patient, the system comprising: an outer weak straight supporter having a first rigidity; an innermost curved supporter , slidably coupled to said outer weak straight supporter , a curved portion of said innermost curved supporter being made of a shape memory material and having a curved shape memory, said curved portion of said innermost curved supporter having a second rigidity greater than the first rigidity, and said innermost curved supporter having a first rectangular cross-sectional shape; and a middle strong straight supporter slidably coupled between said outer weak straight supporter and said innermost curved supporter , said middle strong straight supporter having a third rigidity greater than the second rigidity and comprising: a distal end; a curved supporter recess located at said distal end with a second rectangular cross-sectional shape configured to allow the first rectangular shape of the innermost curved supporter to pass therethrough; a work channel comprising a lumen and a work channel recess also located at said distal end; and an optical sensor disposed in the work channel recess ; wherein when said middle strong straight supporter overlaps said curved portion of said innermost curved supporter , an overlapped portion of said curved portion conforms to a straight shape of said middle strong straight supporter , and when said curved portion overlaps said outer weak straight supporter , an overlapped portion of said outer weak straight supporter conforms to a curved shape of said curved portion. an outer weak straight supporter having a first rigidity; an innermost curved supporter , slidably coupled to said outer weak straight supporter , a curved portion of said innermost curved supporter being made of a shape memory material and having a curved shape memory, said curved portion of said innermost curved supporter having a second rigidity greater than the first rigidity, and said innermost curved supporter having a first rectangular cross-sectional shape; and a middle strong straight supporter slidably coupled between said outer weak straight supporter and said innermost curved supporter , said middle strong straight supporter having a third rigidity greater than the second rigidity and comprising: a distal end; a curved supporter recess located at said distal end with a second rectangular cross-sectional shape configured to allow the first rectangular shape of the innermost curved supporter to pass therethrough; a work channel comprising a lumen and a work channel recess also located at said distal end; and an optical sensor disposed in the work channel recess ; wherein when said middle strong straight supporter overlaps said curved portion of said innermost curved supporter , an overlapped portion of said curved portion conforms to a straight shape of said middle strong straight supporter , and when said curved portion overlaps said outer weak straight supporter , an overlapped portion of said outer weak straight supporter conforms to a curved shape of said curved portion. a distal end; a curved supporter recess located at said distal end with a second rectangular cross-sectional shape configured to allow the first rectangular shape of the innermost curved supporter to pass therethrough; a work channel comprising a lumen and a work channel recess also located at said distal end; and an optical sensor disposed in the work channel recess ; wherein when said middle strong straight supporter overlaps said curved portion of said innermost curved supporter , an overlapped portion of said curved portion conforms to a straight shape of said middle strong straight supporter , and when said curved portion overlaps said outer weak straight supporter , an overlapped portion of said outer weak straight supporter conforms to a curved shape of said curved portion. <EOS>