the parietal anchor instrument shown diagrammatically in fig1 and 2 comprises a clip . it has first and second longitudinal elements 4 and 6 , each made as single piece of metal or plastics material . it presents a length of about 2 centimeters . as can be seen in fig1 , the first and second longitudinal elements 4 and 6 are hinged to each other in their middle portions so as to constitute clip 8 . on either side of a hinge pin 10 , the clip 8 comprises a jaw 12 for holding an organ and means 14 for gripping the instrument and controlling the opening of the jaw 12 . the longitudinal elements 4 and 6 are suitable for pivoting about the pin 10 between a closed position and an open position of the clip 8 . more precisely , the first longitudinal element 4 comprises in succession a pierced flat 16 , a clevis 18 , a connection shank 20 , and a bearing disk 22 . the flat 16 and the disk 22 extend in planes that are parallel but not coplanar . the clevis 18 extends the flat 16 towards the shank 20 . the second longitudinal element 6 is similar in shape to the first element 4 . it thus likewise comprises a flat 24 , a connection shank 26 , and a bearing disk 28 . nevertheless , a convex projection 30 replaces the clevis 18 . the convex projection 30 is engaged in the clevis 18 . the pin 10 passes through the projection 30 and the clevis 18 to hinge the first element 4 to the second element 6 . the two flats 16 and 24 constitute the jaw 12 of the clip for holding an organ . they present anti - skid serrations 32 on their facing faces in order to make it easier to hold human or animal organs . in addition , the flats 16 and 24 include respective oblong through openings 34 extending over their entire length . a spring 35 serves to hold the jaw 12 in a closed position and is mounted between the shanks 20 and 26 . the spring 35 is suitable for exerting a pressure force suitable for bringing the flats 16 and 24 together . thus , at rest , when no pressure is exerted on the outside surfaces of the bearing disks 22 and 28 , the clip 8 is held in a closed or organ - pinching position . the spring 35 is formed by a metal blade secured to the shank 26 and bearing against the shank 20 . the blade is suitable for exerting a force that opposes opening the clip . the bearing disks 22 and 28 and the connection shanks 20 and 26 form means 14 for gripping and controlling opening of the jaw 12 . they enable the anchor instrument to be handled and moved during a surgical operation . the anchor instrument also comprises an arch 36 for attaching at least one traction element 37 to the clip 8 . this traction element is preferably flexible . for example it may be constituted by a thread , a strip , a strap , etc . the traction thread 37 is suitable for being secured to the abdominal wall of the living being to be operated in order to raise and keep in suspension an organ held by the jaw 12 . the thread may also carry an organ at a point situated between the clip and the parietal exit point of the thread , as described below in the method of using the anchor instrument of the invention . the traction thread 37 is secured to the arch 36 , e . g . by a flexible bond . the arch is secured at each end to the pin 10 . the arch 36 is made of a semi - elastic material of the plastics material or rubber type , so that it deforms as a function of the direction in which the thread applies traction . the arch 36 is positioned at a certain distance from the jaw 12 and the means 14 for gripping and controlling said jaw , so that the thread 37 does not wind about them . furthermore , the arch 36 projects from the jaw 12 and the means 14 so as to make it easier to engage an additional traction thread during a surgical operation . the means 14 also include projections 38 projecting from the outside surfaces 39 of the bearing disks 22 and 28 so as to make it easier to grip , handle , and control opening of the clip 8 using a conventional surgical forceps . each projection 38 has a frustoconical end portion 40 and a cylindrical base 41 secured to the bearing disks 22 , 28 . the base 41 has a diameter that is slightly smaller than the diameter of the end windows in conventional surgical forceps so as to enable them to be inserted therein . fig3 shows a parietal anchor instrument in a second embodiment of the invention . this instrument is formed by a double hook 42 . it comprises a rectangular support plate 43 having mounted thereon hook means 44 , means 45 for attaching a traction thread 37 , and means 46 for gripping the anchor instrument . the hook means 44 comprise two hooks 47 and 48 projecting from one side of the plate 43 and both curved in the same direction . the means 45 for attaching a traction thread comprise an arch 49 secured to the side opposite the side that presents the hooks 47 and 48 . the grip means 46 comprise two diverging and curved wings 50 and 51 that are secured to opposite faces of the plate 43 and that form a mean angle α relative to the plane thereof . the angle α is selected to facilitate gripping the instrument by means of surgical forceps regardless of the positioning of the double hook 42 . this positioning is imposed by the location of the trocar and the position of the operating surgeon . in a variant that is not shown , the hook means 44 for hooking an organ comprise a single hook or a triple hook . the parietal anchor instruments shown in fig1 to 3 are example embodiments of the invention that are not limiting in any way . the shape of these instruments varies as a function of the type of organ that is to be held and as a function of its atraumatic nature . in another variant of the first and second embodiments of the invention ( not shown ), the means 36 and 45 for attaching the traction thread are formed by an orifice passing through the anchor instrument . the thread is suitable for being inserted in the orifice and then attached around a wall of the instrument . for example , the orifice may be made through the convex projection 30 and the clevis 18 , or through a connection shank 20 , 26 of the clip 8 . it may also be formed through the support plate 43 . fig4 to 6 show a parietal anchoring method implemented using an anchor instrument constituting the first embodiment of the invention . fig4 is a diagrammatic section view of an operation space defined by an abdominal wall 52 . in a first step of the operation , two trocars 53 and 54 are inserted in the wall 52 . then , during a second step of the operation , an anchor device 58 is brought via the trocar 53 into the operation space 59 of the abdomen . this device 58 comprises an anchor clip 8 , a traction thread 37 , and a needle 62 . one end of the thread 37 is secured to the arch 36 of the clip 8 . the other end of the thread 37 is secured to the needle 62 . in a third step of the operation , shown in fig5 , the surgeon introduces conventional forceps 66 and 68 into each of the trocars 53 and 54 . the surgeon then moves out of the way an organ located in front of the anatomical region on which the operation is to be performed by using one of the forceps 68 . this forceps takes hold of an organ 70 in order to expose the zone on which the operation is to be performed . in order to hold the organ 70 away from the operation zone in a static position , the surgeon or the surgeon &# 39 ; s assistant inserts the projections 38 of the grip and control means 14 of the clip 8 into the windows at the ends of the free forceps 66 or 68 , opens the jaw 12 by using the grip and control means 14 , and takes hold of the organ 70 in the jaws 12 . in a fourth step , shown in fig6 , the surgeon pierces the abdominal wall 52 with a needle 62 manipulated by the forceps 66 at a selected anchor point 73 . the needle 62 and a portion of the thread 37 are thus moved out from the operation space 59 . while this is taking place , the thread 37 pulls the organ 70 and the suspended clip 8 so that the organ 70 moves away from the operation zone . in a fifth step , shown in fig7 , the thread 37 is secured to the outside of the abdominal cavity 59 by fastener means 76 , e . g . comprising a forceps . the thread 37 secured to the abdominal wall 52 thus constitutes a stationary anchor point 73 for the organ 70 . the organ 70 is held away from the operation zone , but without being held by a surgeon &# 39 ; s assistant or a robotic arm . the thread 3 maintains constant traction on the organ 70 without piercing it . in a variant , the thread is attached inside the abdominal cavity to a transparietal intra - abdominal anchor system , i . e . an intraparietal fastener system connected to an extraparietal system that does not pass through a trocar . under such circumstances , a plurality of traction threads can advantageously be attached to the intraparietal fastener system . advantageously , the position of the organ 70 can be readjusted during surgery merely by applying traction on the thread 37 outside the wall ( or vice versa ) and repositioning the fastener means 76 . a variety of anchor instruments 8 , 42 of this type can be used simultaneously during surgery in order to optimize exposure and release the surgical forceps 66 and 68 that pass through the trocars 53 and 54 so as to enable them to perform dynamic roles during the operation . advantageously , the anchor instrument 8 , 42 can be manipulated and moved during surgery so as to hold onto another organ in the abdominal cavity while maintaining the first anchor point 73 secured to the abdominal wall 52 . in parallel , the anchor point 73 of the organ can also be moved so as to obtain another viewing angle on the operation zone , while continuing to hold the organ 70 in the jaw 12 . for example , when the surgeon seeks to orient the organ 70 in another direction , a second thread ( not shown ) can be inserted into the operation space 59 , which thread is secured to the needle 62 . the end of the second thread is secured to the arch 37 of the clip 8 . thereafter the previously attached first traction thread 37 is cut . the second thread is suitable for passing through the wall 50 with the help of the needle 62 at a second anchor point 79 different from the first anchor point 73 . thus , the parietal anchor instrument makes it possible to hold an organ 70 in a certain position for a selected duration at a first anchor point , and then to move the organ 70 and to hold it suspended in a different orientation from a second anchor point 79 . the parietal anchor instrument thus makes it easier to expose an operation zone without requiring an additional trocar and without requiring an extra hand for acting thereon . advantageously , by reducing the number of trocars that are implanted , the number of incisions in the abdominal wall is reduced , thereby accelerating patient recovery by reducing the duration of post - operative convalescence . the anchor instrument serves to reduce the number of surgeon &# 39 ; s assistants needed to assist the surgeon during the operation , such that in the event of a hemorrhage or some other incident , a surgeon &# 39 ; s assistant has an additional hand available for acting and dealing with the incident . advantageously , the gripping end of the clip 8 and the wings 50 , 51 of the double hook 42 can be manipulated by conventional celioscopic instruments . to recapitulate , the method of parietally anchoring an organ of a living being for exposing an anatomical structure that is to be treated during a surgical operation comprises : a first step of inserting a trocar 53 , 54 in the abdominal wall 52 of a human being or an animal ; a second step of introducing a parietal anchor instrument 8 , 42 , a needle 62 , and at least one traction thread 37 into the abdominal cavity 59 , a first end of the thread 37 being connected to the needle 62 and a second end of the thread 37 being connected to the anchor instrument 8 , 42 ; a third step of releasably holding said organ 70 by means of the anchor instrument 8 , 42 , which anchor instrument is suitable for taking hold of different organs in succession during an operation ; a fourth step of transpiercing the abdominal wall 52 from the inside to the outside by means of the needle 62 , or of attaching to a transparietal intra - abdominal anchor system , and then pulling said organ 70 by means of the anchor instrument 8 and the thread 37 ; and a fifth step of securing the first end of the thread 37 to the outside of the abdominal wall 52 with the help of fastener means 76 so as to form a stationary anchor point 73 , 79 for the organ held suspended by the thread and the anchor instrument . this anchoring method is performed during a surgical operation . it is temporary . the organs held suspended by the thread and the anchor instrument are released at the end of the surgery . the anchor instrument constituting the first embodiment of the invention serves to hold and pinch organs without piercing them or damaging them .