Patent Publication Number: US-2020279508-A1

Title: First entry model

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/030,696 filed on Jul. 9, 2018 entitled “First entry model” which is a continuation of U.S. patent application Ser. No. 15/370,231 filed on Dec. 6, 2016 entitled “First entry model” now U.S. Pat. No. 10,026,337 issued Jul. 17, 2018 which is a continuation of U.S. patent application Ser. No. 14/340,234 filed on Jul. 24, 2014 entitled “First entry model” now U.S. Pat. No. 9,548,002 issued on Jan. 17, 2017 which claims priority to and benefit of U.S. Provisional Patent Application Ser. No. 61/857,982 filed on Jul. 24, 2013 entitled “First entry model” and U.S. Provisional Patent Application Ser. No. 61/971,714 filed on Mar. 28, 2014 entitled “First entry model” which are incorporated herein by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     This application relates to surgical training tools, and in particular, to simulated tissue structures and models for teaching and practicing surgical procedures. 
     BACKGROUND OF THE INVENTION 
     Laparoscopic surgery requires several small incisions in the abdomen for the insertion of trocars or small cylindrical tubes approximately 5 to 10 millimeters in diameter through which surgical instruments and a laparoscope are placed into the abdominal cavity. The laparoscope illuminates the surgical field and sends a magnified image from inside the body to a video monitor giving the surgeon a close-up view of the organs and tissues. The surgeon watches the live video feed and performs the operation by manipulating the surgical instruments placed through the trocars. 
     The first step in laparoscopic surgery is to make a small incision to access and create pneumoperitoneum. Pneumoperitoneum is the insufflation of the abdominal cavity with carbon dioxide gas. Insufflation with gas creates a working space in the abdomen necessary for laparoscopy. Once a proper working space has been created, surgical instruments can be inserted for performing a laparoscopic procedure. This process of penetrating the abdomen and creating pneumoperitoneum prior to insertion of other instruments is called first entry. There are many different ways to achieve pneumoperitoneum. One option is using a Veress needle. A Veress needle is approximately 12-15 centimeters long with a diameter of approximately 2 millimeters. The surgeon inserts the spring-loaded needle into the abdomen of the patient after making a small incision. When the needle breaches the inner abdominal space, the spring-loaded inner stylet springs forward to cover the sharp needle in order protect internal organs. The surgeon relies on the tactile feedback of the needle and spring for proper placement. Once proper entry is confirmed, carbon dioxide is introduced through the Veress needle and into the abdominal cavity of the patient expanding the abdomen to creating a working space. 
     Another option is a Hasson technique or cut down technique in which the surgeon makes an initial incision at the umbilicus and the tissue is bluntly dissected. A suture is placed on either side of the incision into the fascia layer to help hold the device in place. The supraperitoneal tissue is dissected away and the peritoneum is incised to enter the abdominal cavity. At this point, a Hasson trocar is inserted into the incision. The Hasson trocar has a blunt tip with suture ties and/or a balloon to hold it in place. After the trocar is placed into the incision, the device is secured with sutures and/or the balloon and carbon dioxide gas is pumped into the patient through the trocar to achieve pneumoperitoneum. 
     Another option is direct trocar entry. In this option, the surgeon uses a bladed or non-bladed trocar either optically or non-optically. The trocar is placed through the layers of the abdominal wall after the initial skin incision is made. When used optically, a camera is inserted into the trocar before entry. After the initial incision is made, the trocar is placed through the layers of the abdomen. Since the camera is present, all of the layers of the abdominal wall can be observed during penetration. Once the surgeon sees that he or she has broken through the peritoneum, penetration can halt, the obturator tip of the trocar pulled back slightly or removed entirely and insufflation can commence by pumping carbon dioxide gas in through the cannula to create pneumoperitoneum. 
     Another option involves a specialized first entry trocar such as the FIOS® first entry trocar made by Applied Medical Resources Corporation in California. Like optical direct trocar entry, a camera is inserted into the FIOS® trocar and the abdominal wall layers are observed during insertion into the abdominal cavity. The specialized FIOS® trocar has a small vent hole in the tip such that instead of requiring that the obturator of the trocar be pulled back or removed completely to introduce carbon dioxide through the cannula, carbon dioxide gas is introduced through the small vent hole in the tip of the obturator with the camera in place. Because carbon dioxide can be introduced through the tip, the FIOS® trocar does not have to penetrate as deeply into the abdominal cavity as a traditional trocar, thereby, affording internal organs greater protection before insufflation can commence. Also, because the obturator does not have to be pulled back or removed, observation via the inserted camera can take place at the point of insufflation. 
     In addition to the above options for entering the abdominal cavity, generally, there are two common places on the abdomen that a surgeon must know how to enter. The most widely used location for first entry is the umbilicus. The umbilicus is a natural weakening in the abdomen where the umbilical cord was attached in the womb. In this part of the abdomen, there are no rectus muscles, arteries or veins so it is generally easier to reach the abdominal cavity. Additionally, the umbilicus is typically an easy place to hide a scar. When surgeons use the umbilicus as an entry site, particularly for the Hasson technique, clamps are often used to grab the base of the umbilicus and the umbilicus is inverted. At this point, an incision is made and the surgeon cuts down as desired and inserts the trocar or Veress needle. With optical entry, the surgeon is able to see all the layers of the abdominal wall. In this location of penetration, they are able to see the fatty tissue, linea alba, transversalis fascia and, finally, the peritoneum. Additionally, when entering at the umbilicus, the umbilical stalk should also be visible. The stalk is what remains of the umbilical cord and it stretches from the skin making up the umbilicus to the peritoneal layer. 
     If a patient has had a previous surgery and adhesions are suspected or a hernia is present at the site of the umbilicus, first entry may need to occur at another location. In this case, the surgeon will often enter from the left upper quadrant since there is less chance of damaging a vital organ in this location. The left upper quadrant is different from the umbilicus region in that there are muscle layers. The rectus abdominus muscles run parallel with the patient&#39;s abdomen and are found on either side of the patient&#39;s midline. Underneath the rectus abdominus muscles run the inferior epigastric veins and arteries which the surgeon must be careful to avoid. When a surgeon is entering the upper quadrant of the abdominal cavity optically, he or she is able to see the skin, fatty tissue, anterior rectus sheath, rectus abdominus, the epigastric vein, which runs through the posterior rectus sheath, and finally, the peritoneum. If the left upper quadrant is not an ideal position for a port, the surgeon may choose to enter at another location such as sub-xiphoid where subcutaneous fat, rectus sheath and peritoneum are present. 
     Since there are many options for first entry, it is important that surgeons have a way to learn and practice the various techniques. There is a need for an anatomical model of the umbilical region and surrounding abdomen that is anatomically correct and includes all the layers of the abdominal wall as well as the veins and arteries that run through the wall. Not only does the model have to be anatomically correct, but also, the model must provide a realistic aural and tactile sensation. For example, when using a Veress needle, two pops are generally felt as the surgeon pushes the needle through the abdominal wall. For optical entry, the surgeon needs to view all of the appropriate tissue layers in the abdominal wall. For entry through the umbilicus, the surgeon must be able to grasp and invert the umbilicus. Also, the model must be able to be used with all four first entry techniques and at multiple (umbilical and upper left quandrant at minimum) entry sites. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention, a simulated tissue structure is provided. The simulated tissue structure includes a support and an artificial anatomical portion. The artificial anatomical portion is configured to simulate a region of an abdominal wall. The anatomical portion is connected to the support such that the anatomical portion is penetrable from a first side to a second side of the anatomical portion. The anatomical portion includes a plurality of simulated tissue layers arranged in juxtaposition with each other. The simulated tissue layers include a simulated skin layer located above the remaining layers. Each of the remaining layers has an opening extending through the layer. The simulated skin layer has a top surface and a bottom surface. The top surface of the simulated skin layer defines a first side of the anatomical portion. The anatomical portion includes a tubular structure having a proximal end and a distal opening at a distal end. The distal end of the tubular extends through one or more of the openings in the remaining layers. In one variation, the proximal end of the tubular structure is connected to the simulated skin layer. The anatomical portion further includes a simulated peritoneum layer having a top surface and a bottom surface. The bottom surface of the simulated peritoneum layer forms the second side of the anatomical portion. The anatomical portion further includes a first layer having a top surface and a bottom surface. The bottom surface of the first layer overlays the top surface of the simulated peritoneum layer. The anatomical portion includes a second layer having a top surface and a bottom surface and the bottom surface of the second layer overlays the top surface of the first layer. The anatomical portion further includes a third layer having a top surface and a bottom surface. The bottom surface of the skin layer overlays the top surface of the third layer. The first layer is made of closed cell polyethylene foam. The second layer is made of fibrous material. The third layer is made of memory polyurethane foam. 
     According to another aspect of the invention, a surgical simulation system is provided. The system includes an abdominal wall model. The model includes a support and an artificial anatomical portion. The artificial anatomical portion is configured to simulate a region of an abdominal wall. The anatomical portion is connected to the support such that the anatomical portion is penetrable from a first side to a second side of the anatomical portion. The anatomical portion includes a plurality of simulated tissue layers arranged in juxtaposition with each other. The simulated tissue layers including a simulated skin layer located above the remaining layers. The simulated skin layer has a top surface and a bottom surface. The top surface of the simulated skin layer defines a first side of the anatomical portion. The surgical simulation system includes a trainer. The trainer includes a base and a top cover having a top surface and a bottom surface. The top cover is connected to and spaced apart from the base to define an internal cavity between the top cover and the base. The top cover has a first opening and the abdominal wall model is removably located inside the first opening. The model is connected to the top cover such that penetration of the anatomical portion provides access to the internal cavity of the trainer. 
     According to another aspect of the invention, a simulated tissue structure configured to simulate an abdominal wall is provided. The simulated abdominal wall structure includes a simulated skin layer having a top surface and a bottom surface. The simulated abdominal wall structure includes a simulated fat layer having a top surface and a bottom surface. The bottom surface of the simulated skin layer overlays the top surface of the simulated fat layer. A first simulated muscle layer having a top surface and a bottom surface is included. A second simulated muscle layer having a top surface and a bottom surface is included. The simulated abdominal wall structure further includes a third layer having a top surface and a bottom surface. The third layer is located between the first and second simulated muscle layers. A fourth layer having a top surface and a bottom surface is provided. A fifth layer having a top surface and a bottom surface is also included. The bottom surface of the fourth layer overlays the top surface of the fifth layer. The simulated abdominal wall structure includes a simulated peritoneum layer having a top surface and a bottom surface. The bottom surface of the fifth layer overlays the top surface of the simulated peritoneum layer. The fourth layer is made of fabric. The simulated fat layer is made of polyurethane memory foam. The simulated skin layer is made of silicone. The third and fifth layers are made of closed cell polyethylene foam. 
     According to another aspect of the invention, a simulated tissue structure is provided. The simulated tissue structure includes a support and an artificial anatomical portion. The support includes a top frame defining a top opening and a bottom frame defining a bottom opening. The artificial anatomical portion is configured to simulate a region of an abdominal wall. The artificial anatomical portion is connected to the support between the top frame and the bottom frame such that the anatomical portion is penetrable through the top opening and bottom opening. The anatomical portion includes a first layer having a top surface and a bottom surface and a second layer having a top surface and a bottom surface. The second layer has a second opening and the bottom surface of the first layer overlays the top surface of the second layer. The anatomical portion includes third layer having a top surface and a bottom surface. The third layer has a third opening or gap and the bottom surface of the second layer overlays the top surface of the third layer. A fourth layer having a top surface and a bottom surface is provided. The fourth layer has a fourth opening or gap and the bottom surface of the third layer overlays the top surface of the fourth layer. A fifth layer having a top surface and a bottom surface is provided. The fifth layer has a fifth opening or gap and the bottom surface of the fourth layer overlays the top surface of the fifth layer. A sixth layer having a top surface and a bottom surface is provided. The sixth layer has a sixth opening or gap and the bottom surface of the fifth layer overlays the top surface of the sixth layer. A seventh layer having a top surface and a bottom surface is provided. The seventh layer has a seventh opening and the bottom surface of the sixth layer overlays the top surface of the seventh layer. An eighth layer having a top surface and a bottom surface is provided. The eighth layer has an eighth opening and the eighth layer is located under the seventh layer. A ninth layer having a top surface and a bottom surface is provided. The ninth layer has a ninth opening and the bottom surface of the eighth layer overlays the top surface of the ninth layer. The third opening/gap, fourth opening/gap, fifth opening/gap and sixth opening/gap are elongate substantially in alignment with each other when the layers are overlayed and have a width and length that extends along a longitudinal axis. The second opening, seventh opening, eighth opening and ninth opening are substantially in alignment with each other and smaller than the elongate openings/gaps of the third opening/gap, fourth opening/gap, fifth opening/gap and sixth opening/gap. All of the openings/gaps overlap at least in part to provide passage of a simulated umbilicus. 
     According to another aspect of the invention, a method for manufacturing a simulated skin layer for a simulated abdominal wall is provided. A mold is provided. The mold includes a cavity having a first depth and a first well inside the cavity having a second depth greater than the first depth. A core is located inside the first well. A silicone mixture is poured into the mold cavity and first well. The silicone is cured inside the mold to form an artificial skin layer having a top surface and a bottom surface and a tubular structure extending from the top surface. The tubular structure is formed with a lumen that defines an opening in the layer at the proximal end and an opening at a distal end. The tubular structure is inverted by passing the distal end of the tubular structure through the opening. A thicker portion is formed around the first well. The opening at the proximal end of the tubular structure is sealed closed with adhesive to simulate an umbilicus. 
     According to one aspect of the invention, a model that allows users to practice first entry surgical procedures is provided. The first entry model includes an anatomical portion connected to a support. The anatomical portion includes a plurality of anatomical layers that is captured between two frame elements which can attach to a laparoscopic trainer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top perspective view of a first entry model according to the present invention. 
         FIG. 2  is top perspective view of a first entry model according to the present invention. 
         FIG. 3  is a top perspective view of a laparoscopic trainer for use with a first entry model according to the present invention. 
         FIG. 4  is a side, exploded view of an anatomical portion of a first entry model according to the present invention. 
         FIG. 5  is a side view of an anatomical portion of a first entry model according to the present invention. 
         FIG. 6  is a top planar view that is representative of more than one layer in an anatomical portion of a first entry model according to the present invention. 
         FIG. 7  is a top planar view that is representative of more than one layer in an anatomical portion of a first entry model according to the present invention. 
         FIG. 8  is top perspective, exploded view of a mold for a skin layer of a first entry model according to the present invention. 
         FIG. 9  is a side, cross-sectional view of a mold for a skin layer for a first entry model according to the present invention. 
         FIG. 10  is a top perspective view of a mold for a skin layer for a first entry model according to the present invention. 
         FIG. 11  is a top perspective view of a mold for a skin layer for a first entry model according to the present invention. 
         FIG. 12  is a side, cross-sectional view of a mold for a skin layer for a first entry model according to the present invention. 
         FIG. 13  is an exploded view of a first entry model according to the present invention. 
         FIG. 14  is a side view of an anatomical portion of a first entry model according to the present invention. 
         FIG. 15  is a bottom planar view of a transversalis fascia layer and umbilical stalk according to the present invention. 
         FIG. 16A  is an end view of a standard first entry model connected to a top cover of a trainer according to the present invention. 
         FIG. 16B  is an end view of an obese first entry model connected to a top cover of a trainer according to the present invention. 
         FIG. 17  is a top planar view that is representative of more than one layer in an anatomical portion of a first entry model according to the present invention. 
         FIG. 18  is a top planar view that is representative of more than one layer in an anatomical portion of a first entry model according to the present invention. 
         FIG. 19  is a top planar view that is representative of more than one layer in an anatomical portion of a first entry model according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to  FIG. 1 , there is shown a model  10  of an abdominal region that includes the umbilicus for practicing surgical first entry into the abdominal cavity for performing laparoscopic surgical procedures. Throughout this specification the model  10  will be referred to as the first entry model  10 . The model  10  includes an anatomical portion  12  connected to a support  14  to form a substantially planar configuration. The support  14  is a frame that encompasses and connects to the perimeter of the anatomical portion  12  and holds the anatomical portion  12  together. In particular, the support  14  includes a top frame and a bottom frame made of plastic material sufficiently rigid to provide structural support and maintain the planar shape of the model  10  and permit the center-located anatomical portion to be penetrated from one side to the other. In one variation, the model  10  is slightly curved to mimic an outwardly curved abdomen. The top frame and the bottom frame connect together capturing the perimeter of the anatomical portion  12  between the top and bottom frames. The model  10  in  FIG. 1  is polygonal having five sides forming a slightly elongated shape wherein one side is curved outwardly in a generally U-shaped configuration. A model  10  having a circular support  14  that frames a circular anatomical portion  12  is shown in  FIG. 2 . The model  10  can be any shape. The frame  14  includes connecting elements  16  configured for connecting the model  10  to a larger laparoscopic trainer  20  as shown in  FIG. 3 . 
     Turning now to  FIG. 3 , a laparoscopic trainer  20  includes a top cover  22  connected to a base  24  by a pair of legs  26  spacing the top cover  22  from the base  24 . The laparoscopic trainer  20  is configured to mimic the torso of a patient such as the abdominal region. The top cover  22  is representative of the anterior surface of the patient and a space  28  defined between the top cover  22  and the base  24  is representative of an interior of the patient or body cavity where organs reside. The laparoscopic trainer  20  is a useful tool for teaching, practicing and demonstrating various surgical procedures and their related instruments in simulation of a patient. When assembled, the top cover  22  is positioned directly above the base  24  with the legs  26  located substantially at the periphery and interconnected between the top cover  22  and base  24  The top cover  22  and base  24  are substantially the same shape and size and have substantially the same peripheral outline. The laparoscopic trainer  20  includes a top cover  22  that angulates with respect to the base  24 . The legs  26  are configured to permit the angle of the top cover  22  with respect to the base  24  to be adjusted.  FIG. 3  illustrates the trainer  20  adjusted to an angulation of approximately 30-45 degrees with respect to the base  24 . A laparoscopic trainer  20  is described in co-pending U.S. patent application Ser. No. 13/248,449 entitled “Portable laparoscopic trainer” and filed on Sep. 29, 2011 by Pravong et al. to Applied Medical Resources Corporation and published as U.S. Patent Application Publication No. 2012/0082970, hereby incorporated by reference in its entirety herein. 
     For practicing various surgical techniques, surgical instruments are inserted into the cavity  28  of the laparoscopic trainer  20  through pre-established apertures  30  in the top cover  22 . These pre-established apertures  30  may include seals that simulate trocars or may include simulated tissue that simulates the patient&#39;s skin and abdominal wall portions. For example, the circular first entry model  10  depicted in  FIG. 2  is connected to the top cover  22  in the location of the central circular aperture  30  that has a conforming circular shape. The top cover  22  of the laparoscopic trainer  20  is configured with a removable insert  32  that is replaceable with the first entry model  10  depicted in  FIG. 1 . The insert  32 , which is provided with apertures  30 , has a shape that conforms to an opening in the top cover  22 . When the insert  32  is removed, the first entry model  10 , such as the one depicted in  FIG. 1 , having a conforming shape is inserted into the opening in the top cover  20  and the connecting elements  16  on the first entry model  10  aid in securing the model  10  to the trainer  20 . 
     Various tools and techniques may be used to penetrate the top cover  20  as described in the background of this description to perform mock procedures not only on the model  10  but also on additional model organs placed between the top cover  22  and the base  24 . When placed inside the cavity  28  of the trainer  20 , an organ model is generally obscured from the perspective of the user who can then practice performing surgical techniques laparoscopically by viewing the surgical site indirectly via a video feed displayed on a video monitor  34 . The video display monitor  34  is hinged to the top cover  22  and is shown in an open orientation in  FIG. 3 . The video monitor  34  is connectable to a variety of visual systems for delivering an image to the monitor  34 . For example, a laparoscope inserted through one of the pre-established apertures  30  or a webcam located in the cavity  28  and used to observe the simulated procedure can be connected to the video monitor  34  and/or a mobile computing device to provide an image to the user. After first entry procedures are practiced on a first entry model  10  connected to the trainer  20 , the first entry model  10  is removed and may be replaced with a new insert or reconstructed and reconnected to the trainer  20  to allow training to continue or be repeated. Of course, the first entry model  10  may be employed independently of the trainer  20  for practicing first entry techniques. 
     Turning now to  FIGS. 4 and 5 , the anatomical portion  12  of the first entry model  10  made of artificial material will now be described. The anatomical portion  12  includes a skin layer  40 , an umbilical stalk  42 , a fat layer  44 , an anterior rectus sheath layer  46 , a first rectus muscle layer  48 , a second rectus muscle layer  50 , a third rectus muscle layer  52 , a posterior rectus sheath layer  54 , a transversalis fascia layer  56 , and a peritoneum layer  58 . The layers  40 ,  44 ,  46 ,  48 ,  50 ,  52 ,  54 ,  56 ,  58  are placed one on top of the other as shown in  FIGS. 5-6  with the umbilical stalk  42  penetrating through all of the layers beneath the skin layer  40 . The layers  40 ,  44 ,  46 ,  48 ,  50 ,  52 ,  54 ,  56 ,  58  are connected together with adhesive or other fastener. In one variation, the layers  40 ,  44 ,  46 ,  48 ,  50 ,  52 ,  54 ,  56  are connected with at least one price-tag holder punched through the layers and sandwiched between the skin layer  40  and the peritoneum layer  58  before being attached to the frame  14 . In another variation, the layers are held together without adhesive or other fastener and are clamped between the top frame and bottom frame. An optional inferior epigastric vein and artery layer  60  is included between the posterior rectus sheath layer  54  and the transversalis fascia layer  56  as shown in  FIGS. 4-5 . 
     With continued reference to  FIG. 4 , the skin layer  40  is molded of silicone or thermoplastic elastomer dyed with a flesh color. The skin layer  40  includes a top surface  62  and bottom surface  64  defining a thickness of approximately 0.1 inches. The skin layer  40  includes an integrally formed umbilical stalk portion  42   a . The skin layer  40  will be described in greater detail below. 
     Still referencing  FIG. 4 , the fat layer  44  is made of cellular polyethylene foam having a yellow color. The cellular foam layer is not solid but textured with air bubbles. The fat layer  44  is approximately 0.625 inches thick. The anterior rectus sheath layer  46  is made of solid ethylene vinyl acetate (EVA) foam having a white color and is approximately 1 millimeter thick. The first rectus muscle layer  48  is made of solid EVA foam and is red in color and approximately 1 millimeter thick. The second rectus muscle layer  50  is made of cellular polyethylene foam having a pink color. The second rectus muscle layer  50  is cellular foam that includes air bubbles that provide a cellular texture and is approximately 0.125 inches thick. The third rectus muscle layer  52  is made of solid EVA foam having a red color and is approximately 1 millimeter thick. The posterior rectus sheath layer  54  is made of solid EVA foam that is white in color and is approximately 1 millimeter thick. The transversalis fascia layer  56  is made of cellular polyethylene foam that is white in color and approximately 0.25 inches thick. The fascia layer  56  has a cellular texture arising from the cellular polyethylene foam as opposed to the solid EVA foam layers. The peritoneum layer  58  is made of solid EVA foam that is white in color and approximately 1 millimeter thick. The inferior epigastric vein and artery layer  60  layer include solid or hollow elongate cylindrical structures made of silicone or Kraton® polymer or other elastomer having a cross-sectional diameter of approximately 0.15 inches. The arteries are red in color and the veins are blue in color. The layers as described above provide an optical entry with a very realistic appearance to the end user. Cellular polyethylene foam is also called closed cell polyethylene foam. 
     Turning now to  FIG. 6 , there is shown a top planar view that is representative of the fat layer  44 , the posterior rectus sheath layer  54 , the transversalis fascia layer  56  and the peritoneum layer  58 . These layers are approximately six inches wide and six and a half inches long. The fat layer  44 , the posterior rectus sheath layer  54 , the transversalis fascia layer  56  and the peritoneum layer  58  all have a circular aperture  66  that is approximately one inch in diameter. The aperture  66  is located approximately two inches from one side and is in the same place in all of these layers  44 ,  54 ,  56 ,  58  such that when overlaid the apertures  66  line up to provide a pathway for the umbilical stalk  42  across these layers. 
     Turning now to  FIG. 7 , there is shown a top planar view that is representative of the anterior rectus sheath layer  46 , first rectus muscle layer  48 , the second rectus muscle layer  50  and the third rectus muscle layer  52 . These layers are approximately six inches wide and six and a half inches long. The anterior rectus sheath layer  46 , first rectus muscle layer  48 , the second rectus muscle layer  50  and the third rectus muscle layer  52  all have an elongate opening  68 . The elongate opening  68  extends along the center line of the layers and is shown in  FIG. 7  to be a rectangular cut out that is approximately one inch wide and 5.75 inches long. When the layers  46 ,  48 ,  50 ,  52  are overlaid, one on top of the other, all of the respective openings  68  are aligned. When the layers  46 ,  48 ,  50 ,  52  are overlaid with the other layers  44 ,  54 ,  56 ,  58 , the apertures  66  are in communication or alignment with the elongate openings  68 . The elongate opening  68  represents the linea alba of the abdomen. 
     With reference back to  FIG. 4  and additional reference to  FIGS. 8-10 , the skin layer  40  is formed by pouring the uncured and dyed silicone or thermoplastic elastomer into a special mold  70 . An exploded, top perspective view of the mold  70  is shown in  FIG. 8 . The mold  70  includes a base  72 , a top  74 , and a core  76 . The base  72  of the mold  70  includes a cavity  78  for receiving the plastic material. The cavity  78  is polygonal and substantially rectangular in shape. The cavity  78  includes a first floor  79  that surrounds a well  80  having a second floor  82 . The second floor  82  of the well  80  is approximately 1 inch below the first floor  79  and includes a hole for inserting the core  76  inside the well  80 . The cross-section of the well  80  is elliptical in shape having a long axis of approximately 1 inch and a short axis of approximately half an inch. The cross-section of the core  76  is also elliptical in shape, complementary to the well  80 . The core  76  has a long axis of approximately 0.75 inches and a short axis of approximately 0.25 inches. With the core  76  in place inside the well  80  a space of approximately ⅛ inch is formed all around the core  76  between the outer surface of the core  76  and the inner surface of the well  80  into which silicone or thermoplastic elastomer is poured to form a tubular structure of the umbilical stalk  42   a  having an opening  92 . The core  76  is approximately one inch and a half in length and extends above the pour line when inside the well  80 . 
     The mold cavity  78  further includes a circumferential well  84  that is formed circumferentially around the first well  80 . The circumferential well  84  has a concave or curved floor  86  that is approximately ⅛ inch deeper from the first floor  79 . When silicone or thermoplastic elastomer is poured, an elliptical toroidal shape with a flat top is formed in the plastic material resulting in an increased thickness of material of approximately 0.25 inch in the area of the circumferential well  84  in the final product. The circumferential well  84  has an inner perimeter  88  that coincides with the wall of the first well  80 . The annular distance from the inner perimeter  88  of the circumferential well  84  to the outer perimeter or end of circumferential well  84  is approximately 0.75 inches. The base  72  of the mold  70  further includes a plurality of pegs  90  upstanding from the first floor  79  to form holes in the resulting molded material. Although the first well  80  is described to have an elliptical shape, in another variation it is circular in shape with a corresponding circular core and circular circumferential well. 
     The core  76  is first inserted into the well  80  and silicone or thermoplastic elastomer is poured into the base  72  of the mold  70 . The silicone or thermoplastic elastomer will run into the well  80  forming a tubular structure defined by the space between the core  76  and wall of the well  80 . The silicone or thermoplastic elastomer will also run into the circumferential well  84  and cover the concave floor  86  forming a substantially toroidal shape of increased thickness of approximately 0.25 inch. The circumferential portion of increased thickness  94  is visible in  FIGS. 4 and 5 . The silicone or thermoplastic elastomer in its liquid state will cover the first floor  79  forming a planar area having a thickness of approximately ⅛ inch. The top  74  of the mold  70  will be placed over the base  72  of the mold  70 . The top  74  is configured to cover only the perimeter of the poured silicone or thermoplastic elastomer to reduce the thickness of the silicone around the perimeter. 
     After the silicone or thermoplastic elastomer has solidified, the top  74  of the mold is removed and the molded silicone or thermoplastic elastomer is removed from the mold  70 . The core  76  is also removed from the material leaving an elliptical opening  92  through the skin layer  40 . The tubular structure or umbilical stalk  42   a  that is integrally formed by the well  80  with the rest of the skin layer  40  defines an opening  92  and is elliptical in shape having long axis of approximately 0.75 inches and a short axis of approximately 0.25 inches with a wall thickness of approximately ⅛ inch. The tubular structure  42   a  is inverted, that is, it is pushed through the opening  92  such that the surface in contact with the floor  79  of the mold  70  becomes the skin layer top surface  62 . This advantageously permits the floor  79  of the mold to include texturing that would impart skin-like texture to the skin layer top surface  62 . Also, by inverting the tubular structure  42   a , not only an umbilical stalk is formed, but also, the portion of increased thickness  94  of the skin layer  40  will advantageously create a raised surface at the skin layer top surface  62  which is clearly visible in  FIGS. 4 and 5 . This raised portion  94  advantageously provides extra thickness of material for drawing sutures through and maintaining them in position without pulling through the silicone or thermoplastic material. Also, a circumferential raised portion  94  that surrounds the opening  92  creates a realistic belly-button effect that can be seen in  FIG. 1 . A variation of the skin layer  40  without the raised circumferential portion  94  is shown in  FIG. 2 . Although the umbilical stalk is approximately one inch long, it may be molded to be longer, approximately 1.25 inches to approximately 2.0 inches long. The skin layer  40  is planar sheet of molded material having a top surface  62  and a bottom surface  64  defining a skin layer thickness of approximately 0.1 inches. The skin layer  40  further includes an opening  92  with a tubular extension  42  integrally formed at opening  92  and interconnected with the rest of the layer  40 . Surrounding the opening  92  is a circumferential raised portion  94  of increased thickness of approximately 0.2 inches. The raised portion  94  provides a convex outer surface that transitions into the remainder of the top surface  62  of the skin layer  40 . 
     The mold  70  is 3D printed from Vero White Plus Fullcure 835 material. The distance from the pour line to the floor  79  is approximately 0.1 inches to create a skin layer thickness of approximately 0.1 inches. Around the perimeter, the thickness beneath the top  74  of the mold  70  is reduced to approximately 0.05 inches for a resulting skin layer thickness at the perimeter having a reduced thickness of approximately 0.05 inches which facilitates connection to the frame support  14 . At the circumferential well  84  location, the thickness of the resulting skin layer  40  is approximately 0.2 inches. First, the mold  70  is sprayed with mold release solution and allowed to dry. In one variation, approximately 5 grams of Dragon Skin Silicone comprising 2.5 grams of part A and 2.5 grams of part B is mixed. Alternatively, a thermoplastic elastomer such as Kraton CL2003X is used for its cost savings and its ability to be sutured. Approximately 20 microliters of fleshtone color is mixed into the silicone. The core  76  is inserted into the well  80  and the silicone mixture is poured into the mold base  72 . The mixture is spread evenly up to a pour line making sure all the wells are filled. The top  74  is placed over the base  72  of the mold  70 . Excess silicone mixture is cleaned away and the silicone inside the mold  70  is allowed to dry for approximately one hour under a heat lamp or for two hours without a heat lamp. 
     After the silicone mixture has dried, the top  74  is removed and the formed skin layer  40  is peeled and removed from the base  72 . The core  76  is also removed. The integrally formed umbilical stalk  42  is inverted by passing it through a formed opening  92 . Silicone adhesive is provided and delivered using a syringe to the inside of the tube of the umbilical stalk  42 . One or more clamps and in one variation, three clamps, such as binder clips, are used to clamp the inverted umbilical stalk  42  closed and sealed to create a bellybutton shape having a star or Y-shaped closure as shown in  FIG. 1 or 2 . The bottom-most part of the umbilical stalk  42  is clamped to create a deep umbilicus as opposed to clamping closer to the skin layer bottom surface  64 . The skin layer  40  is turned over and excess glue that may have seeped out of the umbilicus  42  is removed. The adhesive is allowed to dry for approximately one hour and the clamps are removed. In one variation, an umbilical shaft  42   b  is provided. The umbilical shaft  42   b  is tubular having a central lumen and made of a thin layer of white silicone that is approximately 1 mm thick. The umbilical shaft  42   b  is glued to the umbilical stalk  42   a  to extend the umbilicus deeper into the layers and create a more realistic look and feel. The umbilical shaft  42   b  is glued to the umbilical stalk  42   a  such that the lumens interconnect. The proximal end of the umbilical shaft  42   b  is place over the stalk  42   a  and glued thereto and the distal end of the umbilical shaft  42   b  is free. In another variation, the distal end of the umbilical shaft is glued or integrally formed with the peritoneum layer  58 . 
     All of the layers are properly oriented in the same direction and aligned such that the apertures  66  and openings  68  are superimposed. Then, with the skin layer  40  inverted and the umbilical stalk  42   a  either alone or with an extended umbilical shaft  42   b  is passed through the circular aperture  66  of the fat layer  44  and through the elongate openings  68  of the anterior rectus sheath layer  46 , the first rectus muscle layer  48 , the second rectus muscle layer  50 , and the third rectus muscle layer  52  and then through the circular apertures  66  of the posterior rectus sheath layer  54 , the transversalis fascia layer  56  and the peritoneum layer  58  as shown in  FIG. 5 . In one variation, the umbilicus  42  is left meeting the peritoneum layer  58  or in another variation, the umbilicus  42  is attached with adhesive to the peritoneum layer  58  and yet in another variation, integrally molded with the peritoneum layer  58 . The inferior epigastric vein and artery layer  60  is optionally included. This layer  60  can be formed as a layer having a circular aperture  66  with embedded arteries and veins or simply comprise a pair of cylindrical silicone structures, one red and one blue, placed on one side of the midline and another pair of cylindrical silicone structures, one red and one blue in color, placed on the other side of the midline as shown in  FIG. 4 . The cylindrical silicone structures representing the epigastric veins and arteries are glued to at least one of the adjacent posterior rectus sheath layer  54  and the transversalis fascia layer  56 . A price tag holder or other fastener can then be used to connect the layers together as shown in  FIG. 5  with the umbilicus  42  shown protruding from the aperture  66  in the bottom-most peritoneum layer  58 . 
     As can be seen in  FIG. 5 , the skin layer  50  and the peritoneum layer  58  is slightly larger than the other internal layers  44 ,  46 ,  48 ,  50 ,  52 ,  54 ,  56 . In particular, the skin layer  50  and peritoneum layer  58  are larger by approximately 1.25 inches in length and width. Whereas the internal layers are approximately 6.5 inches long and 6 inches wide, the peritoneum layer  58  and skin layer  40  is approximately 8 inches long and 7.5 inches wide. These extra length and width portions are captured between the top and bottom frames of the support  14 . Pegs in one of the top or bottom frames are passed through apertures in the skin layer  40  formed by mold pegs  90 . The peritoneum layer  58  may also include apertures for passing of frame pegs. The top frame and bottom frame are then heat staked together capturing the anatomical portion  12 . The resulting model  10  is approximately 1.5 inches thick. 
     The first entry model  10  is then placed inside an opening in the top cover  22  of a laparoscopic trainer  20  and securely attached. Laparoscopic first entry procedures such as the ones discussed in the background of this specification are then practiced on the model  10  employing one or more of the trocar instruments described above creating first entry in any of the locations described above including first entry directly through the umbilicus. Another location for first entry could be within a half inch on either side of the midline. Although such first entry is not surgically preferred, the practitioner will advantageously and quickly recognize a mistaken first approach when only the skin layer  40 , the fat layer  44  and posterior rectus sheath  54  and peritoneum  58  layers are observed at the linea alba. The absence of a pink-colored first rectus muscle layer  48  should immediately alarm the practitioner during practice that penetration is at a wrong location. Another location for first entry penetration can take place at the left upper quadrant or right upper quadrant. As mentioned above, the left upper quadrant is different from the umbilicus region in that there are muscle layers. While penetrating at the upper right or left quadrants, the practitioner will observe the following layers: the skin layer  40 , the fat layer  44 , the anterior rectus sheath layer  46 , the first rectus muscle layer  48 , the second rectus muscle layer  50 , the third rectus muscle layer  52 , the posterior rectus sheath layer  54 , the transversalis fascia layer  56  and the peritoneum layer  58 . The layers are configured such that first entry through the umbilicus  42  will not penetrate any of the layers or will only penetrate the skin layer  40 . 
     With reference to  FIGS. 11-12 , there is shown an alternative mold  70  according to the present invention that is used to create the skin layer  40 . The mold  70  is made of a polymer known as Delrin® and includes a base  72 , a top  74 , and a core  76 . The base  72  of the mold  70  includes a cavity  78  for receiving the plastic material. The cavity  78 , which is approximately 0.1 inches deep, is in the shape of a large abdominal wall frame configured to hold all the layers of the model. The cavity  78  includes a first floor  79  that surrounds a well  80  having a second floor  82 . The second floor  82  of the well  80  includes a hole for inserting the core  76  inside the well  80 . The cross-section of the well  80  is elliptical in shape having a long axis of approximately 1 inch and a short axis of approximately half an inch. The well  80  is approximately three inches from one side of the cavity  78  and approximately three inches from the curved side of the cavity  78  and approximately 0.75 inches deep. The well  80  includes a secondary well at the second floor  82  which is also an ovular cutout that has a long axis of approximately 0.5 inches and a short axis of approximately 0.2 inches and approximately 0.1 inches deep. The secondary well is used to align the core  76  within the well  80 . Although the first well  80  is described to have an elliptical shape, in another variation, the first well  80  is circular in shape with a corresponding circular core. 
     The cross-section of the core  76  is also elliptical in shape, complementary to the well  80 . In a cross-section taken perpendicular to the longitudinal axis of the core  76 , the core  76  has a long axis of approximately 0.75 inches and a short axis of approximately 0.25 inches. With the core  76  in place inside the well  80  a space of approximately ⅛ inch is formed all around the core  76  between the outer surface of the core  76  and the inner surface of the well  80  into which silicone or thermoplastic elastomer is poured to form a tubular structure of the umbilical stalk  42   a  having an opening  92 . The core  76  is approximately one inch and a half in length and extends above the pour line when inside the well  80 . The base  72  of the mold  70  further includes a plurality of pegs  90  for forming apertures through which pegs will pass for securing the skin layer  40  to the frame  14 . 
     The core  76  is first inserted into the well  80  and silicone or thermoplastic elastomer is poured into the base  72  of the mold  70 . The silicone or thermoplastic elastomer will run into the well  80  forming a tubular structure defined by the space between the core  76  and wall of the well  80 . The silicone or thermoplastic elastomer in its liquid state will cover the first floor  79  forming a planar area having a thickness of approximately ⅛ inch. The top  74  of the mold  70  will be placed over the base  72  of the mold  70 . The top  74  includes a through-hole having the same shape as the cavity  78  but sized slightly larger so as to cover only the perimeter of the poured silicone or thermoplastic elastomer. The top  74  includes a lip of approximately 0.39 inches in length that extends vertically approximately 0.05 inches. The lip is configured to create a flat edge around the skin layer that is only 0.05 inches allowing the skin layer to be easily heat staked in the location of the edge after assembly. 
     Turning now to  FIGS. 13 and 14 , another variation of first entry model  10  will now be described with like reference numbers used to describe like parts. The model  10  includes an anatomical portion  12  connected between two parts of a frame-like support  14 . The frame-like support  14  includes a top frame having protrusions that snap through the skin layer  40  and into apertures formed in a bottom frame. The anatomical portion  12  includes a skin layer  40 , an umbilical stalk  42 , a fat layer  44 , an anterior rectus sheath layer  46 , a first rectus muscle layer  48 , a second rectus muscle layer  50 , a third rectus muscle layer  52 , a posterior rectus sheath layer  54 , a transversalis fascia layer  56 , and a peritoneum layer  58 . The layers  40 ,  44 ,  46 ,  48 ,  50 ,  52 ,  54 ,  56 ,  58  are placed one on top of the other as shown in  FIGS. 13-14  with the umbilical stalk  42  penetrating through all of the layers beneath the skin layer  40  except for the peritoneum layer  58 . The layers  40 ,  44 ,  46 ,  48 ,  50 ,  52 ,  54 ,  56 ,  58  are connected together with adhesive or other fastener. In one variation, the layers  40 ,  44 ,  46 ,  48 ,  50 ,  52 ,  54 ,  56 ,  58  are connected with at least one price-tag holder  100  punched through the layers and sandwiched between the skin layer  40  and the peritoneum layer  58  before being attached to the frame  14 . In another variation, the layers are held together without adhesive or other fastener and clamped between the top frame and bottom frame. An optional inferior epigastric vein and artery layer  60  is included between the posterior rectus sheath layer  54  and the transversalis fascia layer  56  as shown in  FIGS. 13-14 . 
     With continued reference to  FIGS. 13-14 , the skin layer  40  is molded of silicone or thermoplastic elastomer (TPE) dyed with a flesh color. The skin layer  40  includes a top surface and bottom surface defining a thickness of approximately 0.1 inches. The skin layer  40  includes an integrally formed tubular umbilical stalk portion  42   a  having a central lumen formed by the core  76  during the molding process. An umbilical shaft  42   b  may be formed together with the umbilical stalk  42   a  or connected to the umbilical stalk  42   a  or placed as a separate tubular portion within the anatomical portion  12 . The umbilical stalk  42  is made of a thin layer of white silicone that is approximately 1 millimeter thick. The umbilical stalk  42   a  by itself or together with the umbilical shaft  42   b  is configured to be long enough to travel through all the layers  44 ,  46 ,  48 ,  50 ,  52 ,  54  and  56  until it reaches between the transversalis fascia layer  56  and the peritoneum layer  58 . The distal end of the umbilical stalk  42  (or umbilical shaft  42   b  if one is employed) is cut one or more times such that the cut extends from the distal end of the umbilical stalk towards the proximal end of the umbilical stalk. Several cuts are provided at a length to sufficiently flare the distal end of the umbilical stalk. In one variation, four or more cuts are formed to form four or more pieces or flaps at the distal end of the simulated umbilicus  42 . These flaps  102  are fanned out over the distal-facing surface of the transversalis fascia layer  56  as shown in  FIG. 15 . The umbilical stalk  42  is adhered to the transversalis fascia layer  56  using two types of adhesive. Because the transversalis fascia layer  56  is made of cellular polyethylene foam which is porous, the surface insensitive cyanoacrylate glue cannot be used alone to adhere the silicone because it will burn through the foam and not adhere. Therefore, a heavy duty spray adhesive is sprayed on the foam transversalis fascia layer  56  and allowed to dry for a few minutes. The surface insensitive cyanoacrylate glue is then placed on the silicone umbilical stalk  42  and the distal flaps  102  of the stalk  42  are adhered to the distal-facing surface of the transversalis fascia layer  56 . The spray adhesive, which alone is not strong enough to bond the foam and the silicone, protects the foam from the cyanoacrylate. 
     Still referencing  FIGS. 13-14 , the fat layer  44  needs to react similarly to real fat when grasped or touched externally and it needs to look like fat under optical entry and to respond physically like to fat when pierced internally. In one variation, the fat layer  44  is made of cellular foam that is porous, sponge-like and yellow in color. The yellow foam looks like fat under optical entry. In another variation, the fat layer  44  is made of polyurethane foam that is yellow in color. Memory foam is polyurethane with additional chemicals increasing its viscosity and density. It is also called viscoelastic polyurethane foam or low-resilience polyurethane foam or polyurethane foam having a slow recovery. The memory foam feels realistic when the user touches the model  10  at the skin layer  40  and also when the user enters the fat layer  44  optically with a trocar. When illuminated, the polyurethane fat layer  44  shines advantageously creating the illusion that the fat is wet internally. Additionally, when the fat layer  44  is cut, the polyurethane foam recovers its shape. The ability of the fat layer  44  to recover its shape is important for the Hasson cut-down technique because the surgeon must practice retracting the fat layer  44  before cutting the fascia. The practice is more realistic if the fat layer  44  tends to return to its original location requiring the practitioner to retract the fat layer  44 . In another variation, the fat layer  44  is made of a thermoplastic elastomer (TPE) with an additive such as baking soda or mineral oil to create a material that acts more like real fat. An additive such as baking soda will create a porous fat layer allowing the trocar to easily pierce and enter the fat layer  44  and advantageously provide a more realistic appearance under optical entry. An additive such as mineral oil will create a gel that has the shape-recovery characteristics similar to the memory foam but provides a more realistic feel when touched externally. TPE with either the mineral oil or baking soda as an additive provides a tactile response similar to fat when grasped. The fat layer  44  is approximately 1.5-4.0 cm thick in a standard model  10 . An obese model  10  will be described hereinbelow. 
     In another variation of the model, the skin layer  40  is attached to the fat layer  44 . In particular, the skin layer  40  is cast over the fat layer  44 . The silicone or TPE of the skin layer  40  will adhere to the fat layer  44  located directly below the skin layer  40  as it cures/cools. In such a variation, the mold  70  is made deeper to receive the fat layer  44 . As described above with respect to another variation in which the umbilical stalk is inverted to create a realistic umbilicus, this variation in which the skin layer  40  is attached to the fat layer  44 , the umbilical stalk cannot be inverted because the silicone or the TPE is poured over the fat layer and attaches thereto as it cures. Therefore, the core  76  is a different shape than described above with respect to  FIGS. 11-12 . Instead, the core  76  is shaped such that the cured silicone results in a shape that simulates an inverted umbilicus. For example, the top of the core  76  may be provided with a recess with texturing that simulates the belly button as viewed from outside the patient. The fat layer  44  is placed into the mold base  72  that is modified with a larger receptacle for receiving a fat layer  44  and the silicone or TPE is be poured over it and then the umbilicus-shaped core  76  may be previously placed into a well or is placed on top to mold the umbilicus shape into the silicone skin layer  40  without inverting or gluing a lumen of the umbilical stalk  42 . In this variation, the step of inverting the skin layer  40  and pinched together to create the umbilicus shape would not be needed. 
     In addition to a model with a normal abdominal wall anatomy, an obese model is provided in the present invention. The obese model includes all of the same layers as shown in  FIGS. 13-14  but includes a fat layer  44  that is significantly thicker. The fat layer  44  of the obese model can be made of the same materials already described herein. Whereas the thickness of the standard fat layer  44  is approximately 1.5 to 4.0 cm, the fat layer  44  in the obese model is approximately 4.0 to 7.0 cm. The obese model also includes a special skin layer  40 . The skin layer  40  can be made as previously stated herein and be of the same size in the x-y plane as the skin layer in the standard model or the same size in the x-y plane as the fat layer in the obese model or, alternatively, the skin layer  40  can be larger in size with respect to the size of the fat layer of the obese model in the x-y plane or larger in size with respect to the size of the fat layer of the standard model. If the skin layer is the same size and shape, the obese model  10   b  will have a domed effect as can be seen in  FIG. 16B  when compared to a standard model  10   a  illustrated in  FIG. 16A . The same-sized skin layer  40  in combination with the thicker fat layer  44  or otherwise a skin layer  40  that is the same size or is slightly smaller than the dimensions of the fat layer  44  will result in the thicker fat layer(s)  44  of the obese model being compressed into the same space previously made for the standard model. This compression provides the obese model  10 A with the appearance of an obese patient when using any of the four laparoscopic entry techniques. However, the obese model  10 A will not be easily and realistically grasped with the smaller and tighter skin layer  40  encompassing the larger fat layer  44 ; however, a larger skin layer  40  can be employed. If TPE or memory foam is used for the fat layer  44 , the larger skin layer  40  will allow the fat layer  44  to expand into the extra space of a larger skin layer  40  when gasped and moved. Advantageously, the ability of the fat layer to move freely under the skin layer allows the surgeon to grasp the fat layer and pull at the umbilicus creating a more realistic entry.  FIGS. 16A and 16B  illustrate a laparoscopic trainer  20  with legs  26  removed such that the top cover  22  is seated directly onto the base  24  of the trainer  20  reducing the size of the cavity  28  such that first entry procedures may be more easily and conveniently practiced. The top cover  22  forms a shell over the base  24  and fits securely around an upstanding lip so that the top cover  22  does not dislocate with respect to the base  24 . The first entry model  10  is inserted into an aperture  30  in the top cover  22  of the trainer  20  and a simulated organ is placed into the cavity  28  of the trainer  20  such that when a practitioner enters through the first entry model  10  by piercing the various layers, the practitioner will see the simulated organ located within the cavity  28 . One or more organs may be placed inside the cavity  28 . In one variation, at least a simulated omentum is provided inside the cavity  28 . The simulated omentum is made of a sheet of fabric or thin layer of silicone. The sheet is placed inside the cavity  28  of the trainer  20  and the sheet is configured such that when the first entry model  10  is pierced by an instrument such as an optical trocar having a laparoscope inserted into the trocar, the practitioner will see the sheet on the video display monitor. In one variation, the sheet is suspended within the cavity  28  using clips attached to the trainer  20 . Alternatively, the sheet may be placed on a frame or just laid over the base. The thin sheet of material, representing the omentum, is yellow in color and loosely connected to the trainer and is configured such that it would flutter when insufflation gasses are delivered into the cavity such as with an insufflation trocar after piercing the first entry model  10 . In such a case, the representative omentum layer is attached to the trainer selectively leaving portions of the simulated omentum unattached to enable the flutter effect. The presence of the simulated omentum layer comprising a thin sheet is advantageous because when a surgeon first enters into the abdominal cavity and insufflation is delivered to expand the abdomen in order to create a working space, the surgeon knows that the abdominal wall was successfully entered when visually the representative omentum or viscera is observed and further seen fluttering with the force of insufflation gasses. This training feature is advantageously provided in the present invention in the combination of the first entry model  10 , a trainer  20  and simulated omentum such as that depicted in  FIG. 3  or  FIGS. 16A and 16B  of the present invention. Use of the simulated omentum sheet with the trainer  20  configured as shown in  FIGS. 16A and 16B  advantageously provides a smaller space for the cavity  28 , creating a more air-tight and dark location to simulate insufflation and observe the fluttering of the simulated omentum. 
     With reference back to  FIGS. 13-14  and with reference to Table 1 below, the anterior rectus sheath layer  46  is made of solid ethylene vinyl acetate (EVA) foam having a white color and is approximately 1 millimeter thick. The first rectus muscle layer  48  is made of solid EVA foam and is red in color and approximately 1 millimeter thick. The second rectus muscle layer  50  is made of cellular polyethylene foam having a pink color. In one variation, the second rectus muscle layer  50  comprises two layers  50   a ,  50   b  of cellular polyethylene foam having a total thickness of approximately 0.25 inches. The second rectus muscle layer  50  is cellular foam that includes air bubbles that provide a cellular texture. Each second rectus muscle layer  50   a ,  50   b  is approximately 0.125 inches thick. The third rectus muscle layer  52  is made of solid EVA foam having a red color and is approximately 1 millimeter thick. 
     In one variation, the posterior rectus sheath layer  54  is not made of foam material, but instead, is made of an interfacing fabric. The interfacing fabric is made of strong polyester fibers that can stretch considerably before ripping. Furthermore, the interfacing fabric is thin being approximately 0.2 mm thick and white in color. The interfacing fabric layer  54  is thin enough to allow a trocar or Veress needle to puncture through the fabric when using an entry tactic other than a Hasson cut down technique and capable of being cut when employing the Hasson cut down technique. At the linea alba location, the posterior rectus sheath layer  54  in the model represents the fascia of both the anterior and posterior rectus sheath that come together at the linea alba. The fabric of the posterior rectus sheath layer  54  represents the linea alba configured by exposing the posterior rectus sheath layer through and by way of an elongate opening  68  formed in anterior rectus sheath layer  46 , first rectus muscle layer  48 , second rectus muscle layer  50  and third rectus muscle layer  52 . The elongate opening  68  in each of these layers are shown in  FIG. 17 . In a first entry technique employing the Hasson cut down method, the fascia of the linea alba as represented by the posterior rectus sheath layer  54  is grasped and pulled through the incision in order to safely incise the layer  54 . Hence, the stretchable fabric layer  54  advantageously provides ability to pull the fascia layer up so that safe cutting techniques may be practiced using this model. 
     The transversalis fascia layer  56  is made of cellular polyethylene foam that is white in color and approximately 0.25 inches thick. The fascia layer  56  has a cellular texture arising from the cellular polyethylene foam as opposed to the solid EVA foam layers. The peritoneum layer  58  is made of solid EVA foam that is white in color and approximately 1 millimeter thick. The peritoneum layer  58  may also be made of silicone or TPE. The optional inferior epigastric vein and artery layer  60  layer includes solid or hollow elongate cylindrical structures made of silicone or Kraton® polymer or other elastomer having a cross-sectional diameter of approximately 0.15 inches. The arteries are red in color and the veins are blue in color. The layers, as described above, provide an optical entry with a very realistic appearance to the end user. The layers of foam are capable of being punctured with a trocar and look realistic under optical entry via a laparoscope inserted into an optical trocar. Also, the foam layers provide a realistic tactile feedback to the practitioner when using Veress needle entry as well as with optical entry. The thicknesses, colors and compositions of the various layers of the abdominal wall of the first entry model  10  are shown in Table 1 below. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Abdominal Wall Layers 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 Thickness 
                 Thickness 
                   
               
               
                   
                   
                 Standard 
                 Obese 
                   
               
               
                 Layer 
                 Material  
                 model 
                 model 
                 Color 
               
               
                   
               
               
                 Skin 
                 Silicone or 
                 0.1″ 
                 0.1″ 
                 Flesh  
               
               
                   
                 TPE 
                   
                   
                 Tone 
               
               
                 Fat 
                 Cellular 
                 1.5 to  
                 4.0 to  
                 Yellow 
               
               
                   
                 Foam 
                 4.0 cm 
                 7.0 cm 
                   
               
               
                   
                 Memory 
                   
                   
                   
               
               
                   
                 Foam 
                   
                   
                   
               
               
                   
                 TPE with 
                   
                   
                   
               
               
                   
                 Additive 
                   
                   
                   
               
               
                   
                 Gel 
                   
                   
                   
               
               
                 Anterior  
                 Solid Foam 
                   1 mm 
                   1 mm 
                 White 
               
               
                 Rectus 
                   
                   
                   
                   
               
               
                 Sheath 
                   
                   
                   
                   
               
               
                 Rectus  
                 Solid Foam 
                   1 mm 
                   1 mm 
                 Red 
               
               
                 Muscle 
                   
                   
                   
                   
               
               
                 Rectus 
                 Cellular 
                 1/4″ 
                 1/4″ 
                 Pink or 
               
               
                 Muscle 
                 Foam 
                   
                   
                 White 
               
               
                 Rectus  
                 Solid Foam 
                   1 mm 
                   1 mm 
                 Red 
               
               
                 Muscle 
                   
                   
                   
                   
               
               
                 Posterior  
                 Interfacing 
                 0.2 mm 
                 0.2 mm 
                 White 
               
               
                 Rectus 
                 Fabric 
                   
                   
                   
               
               
                 Sheath 
                   
                   
                   
                   
               
               
                 Transversalis  
                 Cellular 
                 1/4″ 
                 1/4″ 
                 White 
               
               
                 Fascia 
                 Foam 
                   
                   
                   
               
               
                 Peritoneum 
                 Solid Foam, 
                   1 mm 
                   1 mm 
                 White 
               
               
                   
                 Silicone or 
                   
                   
                   
               
               
                   
                 TPE 
               
               
                   
               
            
           
         
       
     
     Turning now to  FIG. 17 , there is shown a top planar view that is representative of the anterior rectus sheath layer  46 , first rectus muscle layer  48 , the second rectus muscle layer  50  and the third rectus muscle layer  52 . These layers are approximately six inches wide and six and a half inches long. The anterior rectus sheath layer  46 , first rectus muscle layer  48 , the second rectus muscle layer  50  and the third rectus muscle layer  52  all have an elongate opening  68 . The elongate opening  68  extends along the center line of the layers and is shown in  FIG. 17  to be a substantially rectangular cut out that is approximately one inch wide and approximately 5.75 inches long. The elongate opening  68  represents the lack of muscle at the linea alba. However, the linea alba varies between patients and in other variations of the model, the width of the elongate opening  68  can range from 8 mm to 30 mm. Of course, the shape of the opening may also vary. When the layers  46 ,  48 ,  50 ,  52  are overlaid, one on top of the other, all of the respective openings  68  are aligned. When the layers  46 ,  48 ,  50 ,  52  are overlaid with the other layers  44 ,  54 ,  56 ,  58 , the ovular holes  66  (described with respect to  FIG. 18 ) are in communication or alignment with the elongate openings  68  and slits  104  (described with respect to  FIG. 19 ). The posterior rectus sheath  54  is visible through the aligned elongate openings  68  simulating the appearance of the linea alba of the abdomen. 
     Turning now to  FIG. 18 , there is shown a top planar view that is representative of the fat layer  44  and the peritoneum layer  58 . These layers are approximately six inches wide and six and a half inches long. The fat layer  44  and the peritoneum layer  58  all have an ovular hole  66  that has a length of approximately one inch and a width of approximately 0.5 inches. The ovular hole  66  is located approximately two inches from one side and is in the same location in the fat layer  44  and the peritoneum layer  58  such that when overlaid the ovular holes  66  line up to provide a pathway for the umbilical stalk  42  across these layers. The ovular hole  66  closely hugs the umbilical stalk  42  compared with a circular hole advantageously providing a more realistic visualization. 
     Turning now to  FIG. 19 , there is shown a top planar view that is representative of the posterior rectus sheath layer  54  and the transversalis fascia layer  56 . These layers  54 ,  56  include a slit  104 . The slit  104  is approximately 1 inch in length and is a narrow cut substantially perpendicular to the representative linea alba so that the ends of the slit  104  are not aligned with the longitudinal axis of the linea alba. The slit  104  allows the umbilical stalk  42  to pass through to its termination between the transversalis fascia layer  56  and the peritoneum layer  58  while still allowing these layers to touch or closely approximate the curvature of the umbilical stalk  42 . In this configuration, the posterior rectus sheath layer  54  and the transversalis fascia layer  56  closely hug the umbilical stalk  42  which advantageously makes the visualization more realistic such that these layers are seen or felt during entry especially when employing a Hasson or Veress needle first entry. In one variation in which the fat layer  44  comprises more than one layer, the one or more distal fat layer(s)  44  are also configured with a slit  104  as shown in  FIG. 19 ; whereas the proximal fat layer(s)  44  are configured with an ovular hole  66  as shown in  FIG. 18 . 
     In another variation, the first entry model  10  includes simulations for adhesions present in real anatomy. Frequently, organs and tissues located underneath the peritoneum will adhere to the peritoneum and create an adhesion. While practicing first entry techniques, it is necessary for the surgeon to learn how to be wary of adhesions and how to navigate with respect to them in the event they occur in the patient. The present invention provides a first entry model that allows the surgeon to practice encountering and navigating adhesions in a first entry laparoscopic environment. It is necessary for the surgeon to be careful, because aggressive entry in the location of an adhesion may result in accidental piercing of the adhered tissue or organ. In this variation of the first entry model  10 , adhesions are included in the model. For example, a simulated adhesion is a piece of simulated bowel that is attached to the undersurface of the peritoneum layer  58 . The piece of simulated bowel is made of silicone. The adhesion may be made of any suitable material and adhesive may be used to connect the adhesion to the peritoneum layer  58 . In another variation, a piece of silicone is used to attach the simulated bowel to the peritoneum layer  58 . In the first entry model with adhesions, the peritoneum layer  58  may be made of silicone or TPE instead of foam in order to more easily attach a silicone adhesion to the peritoneum layer  58 . Also, the peritoneum layer  58  that is made of silicone or TPE will stretch as the adhesion is being removed making the simulation more realistic. To signify that an adhesion is present, a scar indicating a previous surgery may be molded or printed onto the surface of the skin layer  40  in a location above the adhesion to the peritoneum layer; thereby, the surgeon would anticipate an adhesion being present in the general area beneath the layers in the abdominal cavity. The scar would require the practitioner to make a decision about the best place to enter or pierce the first entry model  10  and thus adds an important practice dimension to the model  10 . A scar may or may not be provided. If a scar is not provided on the skin layer  40 , an adhesion may still be provided to surprise the practitioner adding yet another practice dimension to the first entry model  10 . Generally, after the surgeon has entered and found the adhesion, the surgeon can insert a grasper to pull at the adhesion such as a piece of bowel, stretch the adhesion away from the peritoneum and/or bowel, and use a scalpel or scissors to cut through the silicone that is located between the bowel and peritoneum layer  58  and used to attach the simulated adhesion to the peritoneum layer  58  in order to free the adhesion. 
     The first entry model  10  of the present invention is particularly suited for laparoscopic procedures and may be employed with a laparoscopic trainer  20 ; however, the invention is not so limited and the first entry model  10  of the present invention can be used alone to practice first entry surgical procedures equally effectively. The present invention advantageously provides numerous practice possibilities for the surgeon who is learning or practicing first entry techniques while at the same time being manufactured of simple silicone and foam materials providing maximum costs savings while also providing a most realistic tactile and visual experience. The first entry model  10  may be used repeatedly allowing the surgeon to practice numerous entry techniques on the same model before discarding the model which can then be easily replaced with a new model when used with the laparoscopic trainer. 
     It is understood that various modifications may be made to the embodiments of the first entry model  10  disclosed herein. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the present disclosure.