now with first reference to fig1 there is shown a trocar assembly 10 having a housing 11 with an upper opening 32 defined therein for receipt of the outwardmost end of a hand - manipulatable control assembly 33 . the housing 10 has a distal end with an abutment skirt 11a thereon terminating in a receptacle 11b for receipt of first and second concentrically disposed cylindrical members 12 and 13 therethrough and into the housing 11 . a passageway 16 extends completely through the assembly 10 and the innermost of the cylindrical members 13 to an opening 15 . an end 14 is defined on the distal end of the first elongate cylindrical member 12 , which is inserted into the abdominal cavity . as shown in fig1 the first elongate cylindrical member 12 has a retracted outer diameter 17 . now referring to fig2 the first and second elongate cylindrical members 12 and 13 are secured , one to another by means of securements 30 radially spaced there - across at the distal end , such as by spot welding , or the like . the first elongate cylindrical member 12 carries thereon a portion within the housing 11 defining a gear member 19 having inter - engaging teeth at 20 thereon and , preferably , in an annular tooth configuration , 22 . a cylindrical extension 26 has a no - go shoulder 27 ( fig3 ) thereon which contacts the end 19a of the gear member 19 when the cylindrical members 12 , 13 are moved to the normally retracted position , as shown in fig1 to thereby limit travel of the moving cylindrical member in one direction , i . e ., when the cylindrical member 12 is moved by the control 33 from the expanded position , fig2 to the retracted position , fig1 . companion inter - engaging teeth members 21 are provided circularly around a portion of a ring component 21a of the control 33 for inter - engagement with the teeth 20 on the gear member 19 of the first elongate cylindrical member 12 . the extension member 26 has a series of outwardly protruding wing members , 28a , 28b which are inserted in companion slots 29a , 29b on the housing 11 for securement thereto . an outer seal member 31a and companion lip seal 31b , as shown in fig4 prevent transmission of gasses , and other fluids , from within the passageway 16 , when the assembly 10 is within the abdominal cavity , during surgery . an auxiliary instrument i , such as a laparoscope , may be inserted through the seal member 31a and 31b and into the passageway 16 , subsequent to insertion of the assembly 10 within the abdominal cavity and manipulation of the first elongate cylindrical member 12 to the expanded outer diameter 18 , as shown in fig2 . now referring to fig3 and 3a , a sleeve portion 25 is defined immediate the distal end of the first elongate cylindrical member 12 and has a series of radially extending serrated flexing members 23 thereon with openings 24 inter - defined there between . a serration 23a is cut on each of the flexing members 23 to permit flexing movement to the expanding outer diameter position 18 . when it is desired to insert the trocar assembly 10 into the abdominal wall through an incision , or the like , during surgery , the assembly 10 is inserted therein by the surgeon simply grasping the housing 11 and inserting the assembly 10 through such incision , or opening . thereafter , prior to introduction of the auxiliary instrument i through the assembly 10 , the lateral and non - rotating control 33 is contacted by the finger or thumb of the surgeon and moved from the position shown in fig3 backwardly , to the position shown in fig3 a . accordingly , as the control 33 is manipulated , the teeth 21 in the ring 21a will travel across the companion inter - engaging teeth 20 in the teeth configuration 22 of the gear member 19 , such that the first elongate cylindrical member 12 moves non - rotatably and laterally away from the no - go shoulder 27 on the cylindrical extension 26 . because the first and second cylindrical members 12 , 13 are attached one to another by means of the securements 30 at the distal end of the assembly 10 , movement of the first elongate cylindrical member 12 relative to the second member , 13 , will cause the sleeve portion 25 flexing members 23 to be urged radially outwardly from the cylindrical member 12 from the retracted outer diameter of position 17 ( fig1 ) to the expanded outer diameter of 18 ( fig2 ). in the position shown in fig2 the trocar assembly 10 thus resists removal from the abdominal wall w in the cavity , during surgery . the apparatus may be moved from the position shown in fig2 to the position shown in fig1 by reversing the procedure described above , and the assembly 10 completely withdrawn from the abdominal wall w . although the invention has been described in terms of specified embodiments which are set forth in detail , it should be understood that this is by illustration only and that the invention is not necessarily limited thereto , since alternative embodiments and operating techniques will become apparent to those skilled in the art and view of the disclosure . accordingly , modifications are contemplated which can be made without departing from the spirit of the described invention .
a trocar assembly is disclosed for use in inserting a laparoscopic instrument into the abdominal cavity during surgery and includes a cylindrical member activated by intermeshing gears to expand a cylindrical member having a normally retracted outer diameter when the trocar assembly is within the abdominal cavity , to resist withdrawing movement of the assembly from the abdominal cavity .