A three-component model of the spinal nerve ramification: Bringing together the human gross anatomy and modern Embryology.

Due to its long history, the study of human gross anatomy has not adequately incorporated modern embryological findings; consequently, the current understanding has often been incompatible with recent discoveries from molecular studies. Notably, the traditional epaxial and hypaxial muscle distinction, and their corresponding innervation by the dorsal and ventral rami of the spinal nerve, do not correspond to the primaxial and abaxial muscle distinction, defined by the mesodermal lineages of target tissues. To resolve the disagreement between adult anatomy and embryology, we here propose a novel hypothetical model of spinal nerve ramification.

Morphological significance of the medial brachial cutaneous nerve: An anatomical study of the brachial plexus in primates.

The medial brachial cutaneous nerve (MBC) originates from the medial cord of the brachial plexus and innervates the skin sensory in the medial posterior surface of the upper arm. Considering previous reports of the primate brachial plexus, the MBC appeared to be the sole branch in the brachial plexus that only some primates possess. However, the detailed descriptions and records regarding the morphology of the MBC and related nerves, their origins and distributions (dermatomes) in particular, were frequently lacked in the previous reports, and it remains unclear why the difference in the MBC appearance exists among primates.

Relationship of segmental variations in the human lumbar plexus to the length of the 12th rib.

Background: Evaluating segmental variations in the lumbar plexus is crucial for neurological diagnosis. In the present study, we examined the relationship between the segmental composition of the lumbar plexus and length of the 12th rib.

Procedures: To evaluate segmental variations in the lumbar plexus, the furcal nerve (Nf) which forms the boundary between the lumbar and sacral plexus, was used as an index of plexus arrangement.

Variations in the course of the superior gluteal artery in relation to the lumbosacral plexus.

The course of the superior gluteal artery (SGA) as it passes through the lumbosacral plexus is variable. The variations of the arterial course in relation to the lumbosacral plexus have focused on statistical analysis, and it is limited arterial diversity. In this study, we investigated the positional relation between the SGA and the furcal nerve (FN): guide to segmentation of the lumbosacral plexus, arising from the L4, ie, the contribution to the femoral nerve, obturator nerve, and lumbosacral trunk.

Morphological analysis of the branches of the dorsal pancreatic artery and their clinical significance.

The dorsal pancreatic artery (DP), characterized by a course that crosses behind the proximal part of the splenic vein. It is regarded as clinically important, providing essential distribution to the pancreas. However, the origin of the DP is extremely variable and therefore cannot provide a sufficient basis for identifying it.

Variations in the course of the maxillary artery in Japanese adults.

Many authors have studied variation in the maxillary artery but there have been inconsistencies between reported observations. The present research aimed to examine the courses and branching patterns of the trunk and branches of the maxillary artery in a large sample of Japanese adult cadavers. The course of the maxillary artery should be reclassified into seven groups as a clear relationship was found between the origin of the middle meningeal artery and the course of the maxillary artery.

Middle thymothyroid artery arising from the common carotid artery: case report of a rare variation.

A middle thymothyroid artery, arising from the anterior aspect of the right common carotid as an anomalous branch was observed in a 71-year-old Japanese male cadaver. It soon divided into a thyroidea ima artery, a branch supplying the sternoclavicular joints, and a thymic branch. In addition, twigs from these three main branches supplied the sternohyoid and sternothyroid muscles, right inferior parathyroid gland and also some deep cervical lymph nodes.

Nerve fiber analysis of ansa cervicalis-vagus communications.

Communications between the ansa cervicalis and the vagus nerve, although described only as variations in many textbooks, can be observed frequently in the dissection room. Following macroscopic observation, some of such cases were subsequently dissected under surgical microscope to determine the nature of such communications. As a result, two broad categories of communications between the ansa cervicalis complex and the vagus nerve could be recognized: (i) false (pseudo) communications, where the two nerves were attached only by the connective tissue with no fiber exchange; and (ii) true communications, with nerve fiber involvement.

Nerve communication between the glossopharyngeal nerve, external carotid plexus and the superficial cervical ansa: human autopsy case.

The authors encountered a very rare human autopsy case in which the supernumerary branch of the glossopharyngeal nerve and a nerve branch arising from the external carotid plexus communicated with the superficial cervical ansa. This anomaly was observed on the left side of a 71-year-old male cadaver during the gross anatomical seminar at Niigata University in 2004. The nerve fascicle and fiber analyses indicated that the supernumerary branch of the glossopharyngeal nerve separated cranial to the branches to the pharyngeal constrictor muscles, carotid sinus and stylopharyngeal muscle and sent the nerve fibers to the muscular branches to the platysma and the cutaneous branches to the cervical region.

[Reexamination of the communicating branch between the sural and tibial nerves].

Reexamination of communicating branches between the sural and tibial nerves ventral to the calcanean tendon was carried out on 52 legs of 26 Japanese cadavers which were used for ordinary dissection practices at the Niigata University School of Medicine. Communicating branches were found in 7 out of 52 dissections (13.5% of cases).

Intramuscular nerve distribution pattern of the oblique and transverse heads of the adductor hallucis muscles in the human foot.

To understand which layer of the intrinsic muscles of the foot the adductor hallucis muscle belongs to, it is essential to investigate the innervation patterns of this muscle. In the present study, we examined the innervation patterns of the adductor hallucis muscles in 17 feet of 15 Japanese cadavers. We investigated the intramuscular nerve supplies of the adductor hallucis muscles in six feet and performed nerve fiber analysis in three feet.

Formation and distribution of the sural nerve based on nerve fascicle and nerve fiber analyses.

The formation and distribution of the sural nerve are presented on the basis of an investigation of 31 legs of Japanese cadavers using nerve fascicle and fiber analyses. Nerve fibers constituting the medial sural cutaneous nerve were designated as 'T', whereas those constituting the peroneal communicating branch were designated as 'F'. In 74.

[Application of the modified Sihler's stain technique to cadaveric peripheral nerves after medical students' dissection course].

The exact ramification and distribution pattern of the peripheral nerves is one of the most important information for anatomists and clinicians. However, it is very difficult to pursue perfectly all of the fine twigs of nerve branches even if we use a stereoscopic microscope. Recently, Liu et al.

Ramification pattern of the deep branch of the lateral plantar nerve in the human foot.

To understand how the oblique and transverse heads of the adductor hallucis muscle of the human foot are phylogenitically and ontogenetically developed, it is essential to know nerve supplies of these two heads of the muscle. In the present study, we dissected seven feet of five Japanese cadavers in detail to clarify the ramification patterns of the deep branch of the lateral plantar nerve by peeling off its epineurium (the nerve fascicle analysis method). We found that the muscular branch to the oblique head of the adductor hallucis muscle directly separated from nerve fascicles constituting the deep branch of the lateral plantar nerve, whereas the muscular branch to the transverse head arose in common with branches which innervated other intrinsic muscles of the foot, i.

Sural-tibial nerve communications in humans.

We investigated the occurrence of a communication between the sural and tibial nerves in 49 legs of 28 Japanese cadavers. In front of the calcanean tendon, we found the communication in 7 legs (14.3%) or in 5 cadavers (18.