Takashi Shimokawa

Innervation of the pancreas from the perspective of perineural invasion of pancreatic cancer

Introduction Pancreatic cancer invasion via neural routes (perineural invasion) has been studied extensively, but detailed research on the morphology of innervation of the pancreas related to perineural invasion is scarce. Aims To clarify the morphology of neural distribution in the human pancreas. Methodology The pancreas and surrounding structures were dissected in 9 cadavers, the specimens were immersed in a 0.001% solution of alizarin red S in ethanol to stain the peripheral nerves, and the detailed distribution was studied to confirm the extrapancreatic and intrapancreatic plexus using a binocular microscope. Results The innervation of the uncinate process of the pancreas originated from the superior mesenteric plexus (SMPlx) along the inferior pancreaticoduodenal artery (IPDA), but did not form a wide offshoot of nerve bundles as reported. Concerning the innervation of the body and tail, it was found that the nerve fibers entered the pancreas immediately after leaving the celiac plexus, and were distributed around the pancreatic duct in a twig-like manner. Conclusion It was emphasized that the nerve originating from SMPlx to the uncinate process chiefly ran along the IPDA and it was necessary to focus ones attention not only on the extrapancreatic perineural invasion but also on the intrapancreatic perineural invasion in carcinoma of the body and tail of the pancreas.

Positional relationships between the masticatory muscles and their innervating nerves with special reference to the lateral pterygoid and the midmedial and discotemporal muscle bundles of temporalis.

For an accurate assessment of jaw movement, it is crucial to understand the comprehensive formation of the masticatory muscles with special reference to the relationship to the disc of the temporomandibular joint. Detailed dissection was performed on 26 head halves of 14 Japanese cadavers in order to obtain precise anatomical information of the positional relationships between the masticatory muscles and the branches of the mandibular nerve. After complete removal of the bony elements, the midmedial muscle bundle in all specimens and the discotemporal muscle bundle in 6 specimens, derivatives of the temporalis, which insert into the disc were observed. On the anterior area of the articular capsule and the disc of the temporomandibular joint, the upper head of the lateral pterygoid, the midmedial muscle bundle of temporalis and the discotemporal bundle of temporalis were attached mediolaterally, and in 3 specimens the posterosuperior margin of the zygomaticomandibularis was attached to the anterolateral area of the disc. It is suggested that these muscles and muscle bundles contribute to various mandibular movements. Although various patterns of the positional relationships between the muscles and muscle bundles and the their innervating nerves are observed in the present study, relative positional relationships of the muscles and muscle bundles and of nerves of the mandibular nerve are consistent. A possible scheme of the developmental formation of the masticatory muscles based on the findings of the positional relationships between the muscles and the nerves is presented.

Innervation analysis of the small muscle bundles attached to the temporalis: truly new muscles or merely derivatives of the temporalis?

Detailed examinations were performed in ten temporal muscles from five cadavers to identify the muscle bundle arrangements of the temporalis and their innervation. Three additional muscle bundles were clearly observed in the main part of the fan-shaped temporalis: the anteromedial, anterolateral, and mid-lateral muscle bundles. Based on the origins, insertions and detailed innervation patterns, these bundles were considered as parts of the temporalis rather than independent muscles, although the anteromedial and anterolateral bundles had been recently reported as newly described muscles. A possible schematic model of the origins of these muscle bundles is proposed. We also report a branch from the posterior deep temporal nerve which was distributed to the temporal fascia and to the skin of the temporal region.

An extremely rare inversion of the preduodenal portal vein and common bile duct associated with multiple malformations. Report of an adult cadaver case with a brief review of the literature.

A preduodenal position of the portal vein (PDPV) is a very rare congenital anomaly; even rarer is its association with a preduodenal position of the common bile duct (PDCBD). To the seven cases of PDCBD mentioned in the literature, we add this particularly rare case which is associated with multiple abnormalities such as situs inversus totalis, intestinal malrotation, short pancreas, bilobed spleen, accessory spleen, and abnormal ramification of the celiac axis, superior mesenteric artery and renal arteries. Besides describing and illustrating this case, we also discuss the anatomy and embryology of these structures and briefly review the patterns of previously reported cases that we found. We performed an immunohistochemical examination of the pancreas to demonstrate the ventro-dorsal pancreas in our case. For the explanation of the embryology of the PDCBD, the ventro-dorsal pancreas and PDPV malformation, we emphasized the reverse rotation of the ventral pancreas and duodenum.

An anatomical study of the levator veli palatini and superior constrictor with special reference to their nerve supply

We dissected 50 head halves of 25 Japanese cadavers (10 males, 15 females) to investigate the innervations of the levator veli palatini (LVP) and superior constrictor pharyngis. The branches supplying the LVP were classified into the following three types according to their origins: supplying branches that originated from the pharyngeal branch of the glossopharyngeal nerve (type I, four sides, 8%), branches that originated from a communicating branch between the pharyngeal branches of the glossopharyngeal and vagus nerves (type II, 36 sides, 72%), and those that originated from the pharyngeal branch of the vagus nerve (type III, 10 sides, 20%). In previous studies, supplying branches of type I were seldom described. Regarding the innervation of the superior constrictor, some variations were observed, and we consider it likely that there is a close relationship between these variations and the type of innervation of the LVP.

Surgical anatomy of the innervation of the major duodenal papilla in human and Suncus murinus, from the perspective of preserving innervation in organ-saving procedures.

Objectives: Few studies have focused on the detailed surgical anatomy of the innervation of the major duodenal papillary region, especially in relation to duodenum-preserving pancreatic head resection (DPPHR) and its modified procedures, which is crucial to preserving the innervation of the papillary region. The aim of this study is to clarify the neural distribution of the major duodenal papilla in humans. Methods: The pancreas, duodenum, and surrounding structures were dissected in 10 cadavers and immersed in a 0.001% solution of alizarin red S in ethanol to stain the peripheral nerves. The details of the innervation in the above areas were confirmed using a binocular microscope. Similarly, the distribution in 10 Suncus murinus was examined by whole mount immunohistochemistry method with antineurofilament protein antibody. Results: The innervation of the papillary region in humans involved 2 systems. One arose from the celiac plexus, which through the anterior hepatic plexus running along the arcades of the superior pancreaticoduodenal arteries and through the posterior hepatic plexus running along or accompanying the common bile duct (CBD) or Wirsungs duct, innervated the papillary region. The other arose from the superior mesenteric plexus wound around the arcades of the inferior pancreaticoduodenal arteries innervating the papillary region. The results in S. murinus supported those in humans. Conclusions: We emphasize the importance of the nervus-preserving of the major duodenal papilla and CBD by a suitable pancreatic head remnant, preserving the pancreaticoduodenal arterial arcades and avoiding kocherization of the CBD in DPPHR and its modified procedures.

Cutaneous nerve to the subacromial region originating from the lateral pectoral nerve

During dissection practice, a cutaneous branch to the deltoid region, which originated from the lateral pectoral nerve, was found bilaterally in one Japanese male (two of 125 sides, 1.6%). The branch originated from the superior surface of the lateral pectoral nerve, ran on the superior surfaces of the coracoid process and the coraco-acromial ligament, and pierced the deltoid muscle close to the tip of the acromion. The distribution area of this cutaneous branch was similar to the cutaneous branch of the suprascapular nerve. Although the branch from the suprascapular nerve has been reported in man and primates, a minute description of such a branch from the lateral pectoral nerve is not currently available in the literature. According to the detailed analyses of the roots of the lateral pectoral nerve and the suprascapular nerve, the roots of both nerves are close to each other in the upper part of the superior trunk of the brachial plexus. Therefore, these cutaneous branches have different courses, but are considered to be a single nerve to complement the supraclavicular nerves.