Abdomen with bilateral Hernias - Erler Zimmer
Overview of the 3D Model
This comprehensive 3D model is one of the largest and most intricate in the series, encompassing a partial torso from the diaphragm to the proximal thigh. It meticulously preserves varying levels of dissection and captures the rare occurrence of simultaneous indirect and direct inguinal hernias, offering valuable insights into the anatomical foundations of both conditions. Due to the extensive dissection involved, this description is segmented into distinct parts based on views and regions.
The Diaphragm
On the superior aspect of the model, the diaphragm is retained, albeit slightly distorted due to the removal of thoracic ribs during dissection. This portion showcases both the diaphragmatic domes and costodiaphragmatic recesses. The fibrous pericardium is visible on the superior surface of the central tendon, and the terminal part of the inferior vena cava can be observed within the caval foramen. Adjacent to the caval foramen, the oesophagus traverses the oesophageal hiatus, followed by the descending thoracic aorta, located just ventral to the thoracic vertebrae.
The Epigastric and Hypochondriac Regions
Within the abdomen, the anterior abdominal wall, greater omentum, and a substantial portion of the gastrointestinal tract have been removed, exposing retroperitoneal organs and structures. In the upper abdomen, the terminal segment of the oesophagus is preserved, entering the cavity just lateral to the left lobe of the liver. The removal of the stomach unveils the pancreas in its entirety, extending from the head, situated within the curvature of the duodenum, to the tail, which extends toward the capsule of the spleen in the left hypochondrium. Above the pancreas, the splenic artery and common hepatic arteries can be glimpsed, spanning the narrow space between the pancreas, diaphragm, and liver. The splenic artery follows its characteristic tortuous path towards the spleen, bifurcating before reaching the hilum, near the splenic vein. The common hepatic artery divides into the gastroduodenal artery (visible as a cut vessel just inferior to the duodenum) and gives rise to the right gastric artery. These vessels lie superficially in relation to the hepatic portal vein. The superior mesenteric artery and vein traverse anteriorly near the pancreatic head and the horizontal part of the duodenum, while the retained ileocolic artery can be traced to the cecum in the lower right quadrant. The inferior mesenteric vein is partially visible, arising from the retained superior rectal vein, which ascends from the undissected true pelvis and courses superficially across the descending thoracic aorta.
Beneath the liver, the gallbladder is visible, positioned between the right and left anatomical lobes. On the left side, the paths of the renal artery and vein are discernible, passing deep to the pancreas, and the ureters descend from the partially exposed kidneys, running superficially over the psoas major and minor muscles.
The Umbilical and Lumbar Regions
In the umbilical and lumbar regions, most of the organs have been removed to reveal structures in the posterior abdominal wall. In the midline, the descending abdominal aorta and inferior vena cava dominate, with the testicular arteries and veins isolated and traceable towards the inguinal regions. Two right lumbar arteries arise from the aorta, and despite the removal of mesenteries and most of the colon, the inferior mesenteric artery can be observed giving rise to the left colic, sigmoid, and superior rectal arteries. On the right side of the specimen, inferior to the kidney, the subcostal, iliohypogastric, and ilioinguinal nerves are exposed alongside the circumflex iliac artery.
The Hypogastrium and Iliac Regions
In the midline, the bifurcation of the descending abdominal aorta into the common iliac arteries (subsequently dividing into internal and external iliac arteries) can be observed beneath certain overlying structures, such as the testicular vessels and ureters mentioned earlier. On the right side, the obturator artery can be seen originating and coursing towards the anterior pelvis. The confluence of the external, internal, and common iliac veins into the inferior vena cava is also visible. Within the true pelvis, the peritoneum remains intact, covering the urinary bladder adjacent to the pubic symphysis and concealing the rectum's descent from the sigmoid colon. In the right iliac region, the terminal portion of the ileum and cecum with the appendix fills the iliac fossa. The appendix and its appendicular artery are visible just superficial to the testicular artery, vein, and the genitofemoral nerve, which descends toward the inguinal canal. In the left region, the sigmoid colon descends across the iliac fossa. As it nears the anterior abdominal wall, an epiploic appendage contributing to the indirect hernia can be observed just lateral to the retained inferior epigastric artery.
Inguinal Area and Perineum
One noteworthy and distinct characteristic of this model is the demonstration of simultaneous direct and indirect hernias, preserved on the right and left sides, respectively. Although most of the anterior abdominal wall has been removed, the inferior epigastric arteries (along with their accompanying veins) have been retained to facilitate the understanding of herniations. On the right side, a clear protrusion of the parietal peritoneum has formed medially in relation to the inferior epigastric artery, illustrating an indirect herniation event. On the left side, the hernia sac extends laterally relative to the inferior epigastric artery and into the opened spermatic cord, with continuity of the epiploic appendage from the sigmoid colon into the sac.
The skin covering the perineum has been eliminated to showcase the structure of the penis (highlighting both the corpus spongiosum and corpora cavernosa) and the positioning of the testes and spermatic cords in relation to the anterior abdominal wall. On the right side, affected by a direct hernia in this particular case, the spermatic cord has been left intact, allowing for a clear view of the external spermatic fascia from the inguinal region to the testis. On the left side, the spermatic cord has been dissected, revealing the enlarged and varicose testicular vein (indicative of the impact of the exposed indirect hernia within the cord), located just superior to the epididymis and the exposed tunica albuginea of the testis.
Thigh Anatomy
Anterior dissections into the femoral triangle region have been performed on both thighs, with variations in content preservation. On the right side, the femoral sheath has been removed to expose the femoral artery, vein, and the deep inguinal lymph nodes. The femoral artery has been sectioned, with a portion removed to expose the origin of the profunda femoris and to provide better visibility of the great saphenous vein draining into the femoral vein. Just lateral to these structures, the very terminal segment of the femoral nerve is observable. On the left side, a slightly larger dissection window has been created to reveal more of the underlying anterior and medial thigh compartment muscles, ranging from the sartorius and iliopsoas laterally to the pectineus and adductor longus medially. The femoral artery has been preserved, with a well-maintained superficial circumflex iliac artery and the origin of the profunda femoris adjacent to the femoral nerve.
The model concludes at the mid-thigh level. While not the primary focus of the model, the spatial arrangement of structures in the cross-section is discernible. This includes the anteriorly positioned femoral diaphysis with closely arranged anterior compartment muscles and the course of the femoral artery and vein within the subsartorial canal.
