Moriyoshi Nakamura

The clinical anatomy of accessory mental nerves and foramina

Since three‐dimensional computed tomography was developed, many researchers have described accessory mental foramina. The anatomical and radiological findings have been discussed, but details of accessory mental nerves (AMNs) have only been researched in a small number of anatomical and clinical cases. For this article, we reviewed the literature relating to accessory mental foramina (AMFs) and nerves to clarify aspects important for clinical situations. The review showed that the distribution pattern of the AMN can differ according to the position of the accessory mental foramen, and the reported incidence of AMFs differs among observation methods. A review of clinical cases also revealed that injury to large AMF can result in paresthesia. This investigation did not reveal all aspects of AMNs and AMFs, but will be useful for diagnosis and treatment by many dentists and oral and maxillofacial surgeons. Clin. Anat. 28:848–856, 2015.

Influence of a fabella in the gastrocnemius muscle on the common fibular nerve in Japanese subjects

The fabella is a sesamoid bone located in the proximal tendon of the gastrocnemius muscle. In rare cases, its presence may lead to a variety of clinical problems, including fabella syndrome and common fibular (CF) nerve palsy. The purpose of this study was to analyze the morphology of the fabella and CF nerve and discuss the influence of any existing fabellae on the size of the CF nerve. The morphology of the fabella and CF nerve in the popliteal region of the lateral head of the gastrocnemius muscle was investigated in 102 knees of 51 Japanese cadavers. The maximum circumference of the thigh, knee, and calf and the frequency, position, and size of the fabella were measured. In addition, the CF nerve width and thickness were measured proximal to the fabellar region and again as the CF nerve passed posterior, lateral, or medial to the region. A fabella was observed in 70 knees (68.6%). The CF nerve adjacent to the fabella was significantly wider and thinner than in the region proximal to the fabella (P < 0.001). In cases in which a bony fabella was present, there was a significant relationship between the thickness of the CF nerve and the circumference of the thigh and knee. The following factors were observed to contribute to the presence of a fabella causing alterations in the size of the CF nerve: a bony fabella, a CF nerve path posterior or lateral to the fabella, and subjects with a thin physique and bony fabella. Clin. Anat. 26:893–902, 2013.

Aortic Arch Origin of the Left Vertebral Artery: An Anatomical and Radiological Study with Significance for Avoiding Complications with Anterior Approaches to the Cervical Spine

Complications from anterior approaches to the cervical spine are uncommon with normal anatomy. However, variant anatomy might predispose one to an increased incidence of injury during such procedures. We hypothesized that left vertebral arteries that arise from the aortic arch instead of the subclavian artery might take a more medial path in their ascent making them more susceptible to iatrogenic injury. Fifty human adult cadavers were examined for left vertebral arteries having an aortic arch origin and these were dissected along their entire cervical course. Additionally, two radiological databases of CTA and arteriography procedures were retrospectively examined for cases of aberrant left vertebral artery origin from the aortic arch over a two‐year period. Two cadaveric specimens (4%) were found to have a left vertebral artery arising from the aortic arch. The retrospective radiological database analysis identified 13 cases (0.87%) of left vertebral artery origin from the aortic arch. Of all cases, vertebral arteries that arose from the aortic arch were much more likely to not only have a more medial course (especially their preforaminal segment) over the cervical vertebral bodies but also to enter a transverse foramen that was more cranially located than the normal C6 entrance of the vertebral artery. Spine surgeons who approach the anterior cervical spine should be aware that an aortic origin of the left vertebral artery is likely to be closer to the midline and less protected above the C6 vertebral level. Clin. Anat. 30:811–816, 2017.

Communicating branches between lingual and hypoglossal nerve: observation using Sihler’s staining technique

PurposeMany dental procedures are at risk of injuring the lingual nerve. We performed this study to better elucidate the microanatomy that exists between the ipsilateral lingual and hypoglossal nerves so that iatrogenic injury can be avoided.MethodsAdult human cadaveric tongues (ten sides) underwent Sihler’s staining to identify the microanatomy between the lingual and hypoglossal nerves.ResultsThe lingual nerve entered the middle part of the anterior two-thirds of the tongue from its lateral side and divided into two to four thick branches. These branches were then disseminated to the anterior, middle, and posterior parts of the anterior two-thirds of the tongue via 7–14 thin nerve bundles as terminal branches. The hypoglossal nerve entered the tongue at the posterior border of its anterior two-thirds and traveled forward to the apex of the tongue on all sides. All specimens were found to have communicating branches between the lingual and hypoglossal nerves at its anterior, middle, and posterior thirds.ConclusionsOur results indicate that the ipsilateral lingual and hypoglossal nerves constantly have three connections on each side between them. This knowledge might aid the dentist in minimizing iatrogenic nerve injury.

Anatomical Research of the Three-dimensional Route of the Thoracodorsal Nerve, Artery, and Veins in Latissimus Dorsi Muscle.

Background: The latissimus dorsi (LD) muscle flap has been widely used in facial reanimation surgery. However, there are no standards to what degree the muscle flap may be safely thinned because the three-dimensional positional relationship of thoracodorsal artery, vein, and nerve inside the LD muscle is poorly understood. Methods: From 18 formalin-fixed cadavers, we made 36 transparent specimens of LD muscles using a newly developed decoloration technique. In 26 specimens, nerve staining (Sihler’s staining method) and silicone rubber (Microfil) injection to the thoracodorsal artery were performed, and the relationship of the artery and the vein was examined in 10 specimens. Results: The thoracodorsal artery and vein always ran parallel in a deeper layer compared to the nerve. The thoracodorsal nerve constantly existed in a deeper layer than half (50%) of the muscle in the range of use of the muscle flap in facial reanimation surgery. Conclusions: The thoracodorsal nerves ran in a shallower layer, and the depth to the nerve in the muscle flap in actual facial reanimation surgery is safe enough to avoid damage to the nerves. The LD muscle may be thinned to half its original thickness safely.

Intraoral vertico-sagittal ramus osteotomy: modification of the L-shaped osteotomy

The sagittal split ramus osteotomy and intraoral vertical ramus osteotomy carry the potential risk of postoperative nerve paralysis, bleeding, and fracture and dislocation of the condyle. In 1992, Choung first described the intraoral vertico-sagittal ramus osteotomy for the purpose of avoiding postoperative dislocation of the condyle. However, there is still potential for damaging the inferior alveolar nerve and maxillary artery with this technique. The authors have developed a modified technique to minimize these risks. An evaluation of surgical experience and patient outcomes with the use of this technique is presented herein. One hundred twenty-two sides in 97 Japanese patients diagnosed with a jaw deformity were analyzed. This technique includes a horizontal osteotomy that is performed at a higher position than in the original Choung procedure. Intraoperatively, there was no unexpected bleeding from the operative site. Proximal segment dislocation from the glenoid fossa was observed on one side (0.82%). Non-union of the osteotomy was not observed in any patient. Intraoperative fracture of the coronoid process occurred in 2.46%, but none necessitated treatment of the fracture. Nerve dysfunction was found in 2.46% at the 12-month postoperative follow-up. The modified technique presented herein was developed to reduce postoperative nerve dysfunction and intraoperative hemorrhage.

Clinical Application of the IllumiScan Fluorescence Visualization Device in Detecting Oral Mucosal Lesions

Objective: Fluorescence visualization devices are screening devices that can be used to examine lesions of the oral mucosa non-invasively. We observed oral squamous cell carcinoma (OSCC) and leukoplakia using the IllumiScan (Shofu, Kyoto, Japan) fluorescence visualization device and examined its usefulness and characteristics. Methods: We investigated 31 OSCC and nine leukoplakia in patients who were examined using the IllumiScan and treated in our department from January 2017 to February 2018. Images taken with the IllumiScan were analyzed using image analysis software. We also examined the lesions using narrowband imaging (NBI). Additionally, the IllumiScan and NBI images and the non-stained areas of iodine staining method (IOM) were visually evaluated. Results: The average luminance of OSCC in the keratinized mucosa was significantly lower than that of OSCC in non-keratinized mucosa. The average luminance of OSCC was significantly lower than that of leukoplakia. Even in keratinized mucosa where IOM is impossible to use, the OSCC lesion exhibited fluorescence visualization loss. Conclusion: The application of the fluorescence visualization device to the oral mucosa may be useful for distinguishing between cancer and normal areas and can be used to detect OSCC in the keratinized mucosa. The use of the IllumiScan in combination with other conventional screening methods may lead to a better diagnosis.