PROBLEM TO BE SOLVED: To provide a retractor capable of adjusting the length between annular members at both ends, wherein an extracorporeal annular member has a sufficient torsional rigidity to prevent winding removal of a flexible sleeve from the annular member when the operation force to the extracorporeal annular member is released while securing the easiness in twisting of the extracorporeal annular member in adjusting the length.SOLUTION: The retractor includes the cylindrical flexible sleeve 4, the extracorporeal annular member 2 and an intracorporeal annular member 3 at both ends of the flexible sleeve 4. The extracorporeal annular member 2 includes square blocks 21 and strip-shaped elastic bodies 22 alternately aligned in a circumferential direction and linked to one another. When the strip-shaped elastic bodies 22 are extended, the square blocks 21 are separated from each other in the circumferential direction. When the strip-shaped elastic bodies 22 are contracted, the square blocks 21 are brought into contact with each other in the circumferential direction. Each square block 21 generates torsional resistance of the extracorporeal annular member 2 in the contact in the circumferential direction with an adjacent square block 21 in the circumferential direction.COPYRIGHT: (C)2013,JPO&INPIT【課題】両端の環状部材間の長さ調整可能な開創器において、長さ調整時の体外側環状部材のねじり易さを確保しつつ、体外側環状部材への操作力の解除時には、環状部材からの可撓性スリーブの巻き外しを防止する十分なねじり剛性を体外側環状部材がもつようにする。【解決手段】筒状の可撓性スリーブ4と、可撓性スリーブ4の両端の体外側環状部材2及び体内側環状部材3とを備える。体外側環状部材2は、周方向へ交互の配列で相互に連結された角形ブロック21と帯状弾性体22とを備えている。帯状弾性体22は、伸長時には角形ブロック21を周方向へ離反させ、縮小時には角形ブロック21を周方向へ接触させる。角形ブロック21は、周方向隣りの角形ブロック21との周方向接触に体外側環状部材2のねじり抵抗力を生じさせる。【選択図】図2
