Dissection of the anterior abdominal wall and the deep inguinal region from a laparoscopic perspective.

The usual dissection by medical students of the anterior abdominal wall and the inguinal region proceeds from superficial to deep; special emphasis is placed on the sheath of the rectus abdominis muscle and lateral muscular layers. We suggest an alternate approach to dissection of this region that has the following advantages: (1) sparing of delicate deep structures not often fully appreciated by students; (2) provision of an opportunity to visualize the region from a laparoscopic surgeon's vantage point; (3) considerably reduced time spent dissecting and identifying structures and relationships, especially peritoneal reflections important in laparoscopic procedures. Our dissection begins with bilateral subcostal incisions through the entire thickness of the anterior abdominal wall and peritoneum, which extend laterally and inferiorly to the level of the anterior superior iliac spines, thereby forming a large, inverted, U-shaped flap. This flap is reflected inferiorly, allowing abdominal viscera to be dissected, and ultimately removed en bloc. The flap is then drawn cranially and stretched somewhat to approximate its position when the abdomen is inflated with CO2 during laparoscopic procedures. Major landmarks, including the deep inguinal ring, are noted and the flap is again reflected inferiorly for dissection beginning with the peritoneum and transversalis fascia. This method of dissecting the anterior abdominal wall and inguinal region results in more facile and timely identification of both superficial and deep structures of the anterior abdominal wall and inguinal region, and provides a clinically relevant demonstration of anatomy from a laparoscopic perspective.

The riddle of the sphincters. The morphophysiology of the anorectal mechanism reviewed.

Although easily taken for granted when functioning properly, malfunction of the anorectal mechanism presents profound inconvenience and embarrassment. The anal sphincters, internal and external, have been the subjects of extensive study yet much appears to remain unsettled. Each sphincter has been proposed, at one time or another, to be the sine qua non of fecal continence, and both clinical and nonclinical studies have often yielded contradictory results. For example, it has been established that the internal sphincter is actually relaxed during the moments of greatest need! On the other hand, the external sphincter can be fully contracted only for a matter of seconds before becoming fatigued. Anatomic studies of the external sphincter date from 1715, yet it has defied consistent and consensual description. A rather persistent theme has been the claimed existence of anatomic subdivisions (e.g., deep, superficial, and subcutaneous). Some form of this traditional description is found in all modern anatomic texts; however, when dissecting, the student is invariably disappointed in his or her efforts to discern the subdivisions. Further, the roles of other important, nonsphincteric mechanisms are often overlooked. This presentation will briefly review the controversial history of the anorectal mechanism and correlate the results of both clinical and anatomic/physiologic studies. By so doing, a functional concept of the structure of the anorectal mechanism emerges.