It is well accepted that the aortic plexus is a network of pre-and post-ganglionic nerves overlying the abdominal aorta, which is primarily involved with the sympathetic innervation to the mesenteric, pelvic and urogenital organs. Because a comprehensive anatomical description of the aortic plexus and its connections with adjacent plexuses are lacking, these delicate structures are prone to unintended damage during abdominal surgeries. Through dissection of fresh, frozen human cadavers (n = 7), the present study aimed to provide the first complete mapping of the nerves and ganglia of the aortic plexus in males. Using standard histochemical procedures, ganglia of the aortic plexus were verified through microscopic analysis using haematoxylin & eosin (H&E) and anti-tyrosine hydroxylase stains. All specimens exhibited four distinct sympathetic ganglia within the aortic plexus: the right and left spermatic ganglia, the inferior mesenteric ganglion and one previously unidentified ganglion, which has been named the prehypogastric ganglion by the authors. The spermatic ganglia were consistently supplied by the L1 lumbar splanchnic nerves and the inferior mesenteric ganglion and the newly characterized prehypogastric ganglion were supplied by the left and right L2 lumbar splanchnic nerves, respectively. Additionally, our examination revealed the aortic plexus does have potential for variation, primarily in the possibility of exhibiting accessory splanchnic nerves. Clinically, our results could have significant implications for preserving fertility in men as well as sympathetic function to the hindgut and pelvis during retroperitoneal surgeries.

PURPOSE Metastatic testis cancer in the retroperitoneum presents a technical challenge to urologists in the primary and post-chemotherapy setting. Where possible, bilateral nerve-sparing retroperitoneal lymph node dissection (RPLND) should be performed in an effort to preserve ejaculatory function; however, this is often difficult to achieve given the complex neurovascular anatomy. To address this, we performed the first comprehensive examination of the anatomical relationships between the sympathetic nerves of the aortic plexus and the lumbar vessels to facilitate navigation and nerve-sparing during bilateral RPLND. MATERIALS AND METHODS The relative anatomy of the infrarenal vasculature (lumbar vessels, right gonadal vein, and inferior mesenteric artery) was investigated in 21 embalmed human cadavers. The complex relationships between these vessels and the sympathetic nerves of the aortic plexus were examined by dissection of an additional 8 fresh human cadavers. RESULTS Analysis of the infrarenal vasculature from 21 cadavers demonstrated that the position of the right gonadal vein and the inferior mesenteric artery may be useful to locate the right superior lumbar vein and 1st pair of infrarenal lumbar arteries; and the common lumbar trunk (vein) and 2nd pair of infrarenal lumbar arteries, respectively. Furthermore, it was revealed that the lumbar splanchnic nerves supplying the aortic plexus were most often positioned antero-medial to the respective lumbar vein. CONCLUSIONS The present study describes the complex neurovascular relationships that are crucial to performing a successful nerve-sparing RPLND, and surgical techniques are discussed. Collectively, these results may help surgeons to reduce post-operative retrograde ejaculation and/or anejaculation.

The lumbar arteries and veins are segmentally arranged vessels in the abdomen that supply the vertebrae and posterior abdominal/paravertebral muscles. Recent studies have indicated that these vessels have a tendency to vary from the classical description of bilateral pairing. The objective of this study was to more accurately characterize the anatomy of the lumbar vessels through the dissection of 22 cadaveric specimens and examination of 41 patients' computed tomography angiography scans. The positions of the lumbar vessels were measured in reference to the bifurcation/confluence of the common iliac arteries/veins. In 22 cadaveric specimens, the course of the lumbar veins was dissected to the psoas major muscle to characterize venous tributaries. Our results indicate that the lumbar veins were rarely paired, segmentally diverged closer to the iliocaval confluence, and preferentially drained into the left side of the IVC. Several types of lumbar veins were additionally characterized based on their consistent coursing patterns. In contrast, the lumbar arteries exhibited pairing, and these successive pairs were found to be equally spaced along the length of the infrarenal abdominal aorta. In specimens where the median sacral artery and 4th lumbar artery pair arose from a trifurcating common trunk, the positions of the 3rd and 4th lumbar arteries were significantly inferior (P < 0.05) compared to those with independent median sacral arteries. Clinically, proper management of the anatomical patterns described in this study may be pivotal in reducing the incidence of intraoperative damage to the lumbar vessels, and may help in the treatment of vascular diseases.

The palmaris brevis (PB) is a small muscle of variant morphology located on the ulnar aspect of the palm, superficial to the hypothenar eminence. Functionally, the PB has been proposed to protect the neurovasculature of the ulnar canal from compressive forces during repetitive or intermittent trauma associated with grasping. Although PB function has been inferred from cadaveric observations, it is unknown whether it has the contractile capacity and fatigue-resistance necessary to withstand these functional demands. Insight into the functional specialization of the PB can be provided through investigating the proportions of type I and type II muscle fibers by staining for myosin heavy chain (MHC) isoforms using immunohistochemical methods. Therefore, the purpose of this study was to quantify the proportion of type I and type II muscle fibers to provide insight into the role of the PB in palmar function based on its gross histological structure. Sixteen PB specimens were harvested from the hands (eight right, eight left) of eight formalin-embalmed cadavers (mean age: 75 ± 14 years; three males, five females). PB muscle composition was determined by labeling serial cross-sections with MHC type I and type II monoclonal antibodies. The results indicate that the PB is primarily composed of type I muscle fibers (72.2 ± 13.7%), with no significant differences between left and right hands. Given the predominance of type I muscle fibers, our findings indicate the PB may be fatigue-resistant and thus, capable of contracting for prolonged durations. This supports cadaveric observations indicating that the PB functions to protect the ulnar neurovasculature of the palm by providing a muscular barrier in addition to serving as a functional anchor to the hypothenar fat pad when objects are firmly compressed into the palm.

Injury to the nerves of the aortic-and superior hypogastric plexuses during retroperitoneal surgery often results in significant post-operative complications, including retrograde ejaculation and/or loss of seminal emission in males. Although previous characterizations of these plexuses have done well to provide a basis for understanding the typical anatomy, additional research into the common variations of these plexuses could further optimize nerve-sparing techniques for retroperitoneal surgery. To achieve this, the present study aimed to document the prevalence and positional variability of the infrarenal lumbar splanchnic nerves (LSNs) through gross dissection of 26 human cadavers. In almost all cases, two LSNs were observed joining each side of the aortic plexus, with 48% (left) and 33% (right) of specimens also exhibiting a third joining inferior to the left renal vein. As expected, the position of the LSNs varied greatly between specimens. That said, the vast majority (98%) of LSNs joining the aortic plexus were found to originate from the lumbar sympathetic trunk above the level of the inferior mesenteric artery. It was also found that, within specimens, adjacent LSNs often coursed in parallel. In addition to these nerves, 85% of specimens also demonstrated retroaortic LSN(s) that were angled more inferior compared with the other LSNs (P < 0.05), and exhibited a unique course between the aorta/common iliac arteries and the left common iliac vein before joining the superior hypogastric plexus below the aortic bifurcation. These findings may have significant implications for surgeons attempting nerve-sparing procedures of the sympathetic nerves in the infrarenal retroperitoneum such as retroperitoneal lymphadenectomies. We anticipate that the collective findings of the current study will help improve such retroperitoneal nerve-sparing surgical procedures, which may assist in preserving male ejaculatory function post-operatively.