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 (156, 700) slidably coupled between said outer weak straight supporter and said innermost curved supporter, said middle strong straight supporter (156, 700) 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 (156, 700) 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 (156, 700), 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 (156, 700) slidably coupled between said outer weak straight supporter and said innermost curved supporter, said middle strong straight supporter (156, 700) 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 (156, 700) 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 (156, 700), 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 (156, 700) 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 (156, 700), 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.