Endoscopic surgical instrument

DETAILED DESCRIPTION OF THE INVENTION The invention now will be described in greater detail with respect to the accompanying drawings which illustrate a preferred embodiment of the invention and wherein: FIG.
1 is a perspective view of a cannula which comprises a first component of the present invention; FIG.
2 is an enlarged sectional view taken along line 2--2 of FIG.
1; FIG.
3 is an enlarged sectional view taken along line 3--3 of FIG.
1; FIG.
4 is a perspective view of a scalpel member which comprises a second component of the present invention; FIG.
5 is an enlarged sectional view taken along line 5--5 of FIG.
4; FIG.
6 is an enlarged fragmented view of a portion of the scalpel member illustrated in FIG.
4; FIG.
7 is an enlarged sectional view taken along line 7--7 of FIG.
6; FIG.
8 is a perspective view of the cannula and scalpel member combined in operative relationship, the cutting edge of the scalpel member being retracted within the cannula and the cannula supporting an optical device which comprises a third component of the present invention; and FIG.
9 is a perspective view corresponding to FIG.
8, but with the scalpel member's cutting edge exposed.
Referring to FIGS.
1-3, a cannula 10 is provided for receiving a scalpel member in a manner hereinafter to be described.
The cannula comprises a rigid hollow cylinder.
A first support element 12 is secured to one end of the cannula.
Element 12 is provided with an aperture 14 extending parallel to the cannula's longitudinal axis.
A clamping screw 16 passes through a wall of element 12 into aperture 14 for a purpose which will be detailed hereinafter.
Adjacent its opposite end, cannual 10 has secured thereto a second support element 18 provided with an aperture 20 axially aligned with aperture 14 of element 12.
FIGS.
4-7 illustrate a scalpel member 22 comprising an elongated hollow cylindrical element 24 having an outer diameter which is slightly less than the inner diameter of cannula 10.
At one of its ends, the wall of element 24 is provided with a substantially U-shaped slot 26