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Many skin flaps have been described for fingertip reconstruction; however, they have not been compared histologically. The aim of this study is to compare the histological features of common insensate flaps that are used for fingertip reconstruction.Skin from fingertips and common flap donor sites on the hand and forearm of cadavers were harvested. This study investigated four histological characteristics, namely thickness of the epidermis and dermis; the ratio of collagen to elastic fibres (C/E ratio) in subdermal tissues, and distribution densities of Merkel cells and Meissner's corpuscles. It then compared the values obtained to determine which flap donor site best matched the fingertip.Epidermal thickness of the reverse digital artery island flap, thenar flap, and hypothenar flap was similar to that of fingertip tissue; dermal thickness of the hypothenar flap was similar to that of fingertip tissue. The C/E ratio of the reverse digital artery island flap was similar to that of fingertip tissue. Merkel cells were abundant in the reverse digital artery island flap, but Meissner's corpuscles were few in each of the flaps compared with fingertip tissue.The flap donor site with histological properties most similar to fingertip tissue was the palmar lateral aspect at the finger base, representative of the reverse digital artery island flap with respect to epidermal thickness, C/E ratio, and presence of Merkel cells. The thenar and hypothenar flaps also showed similar properties.

Background: Several biomechanical studies have shown that the acromioclavicular (AC) ligament prevents posterior translation of the clavicle in the horizontal plane. In anatomy textbooks, however, the AC ligament is illustrated as running straight across the AC joint surface. Hypothesis: The AC ligament does not run straight across the joint surface, and the configuration of the AC ligament may vary. Study Design: Descriptive laboratory study. Methods: We used 16 pairs of shoulder girdles in this study. After identifying the AC ligament, we macroscopically investigated the orientation and attachment of the ligament and measured the angle between the ligament and the line perpendicular to the AC joint surface by using a digital goniometer. In addition, the AC joint inclination angle was measured, and the Spearman rank correlation coefficient between the joint inclination and the ligament angle was calculated. Finally, we sought to classify the AC ligament based on its configuration. Of the 16 pairs of specimens, 3 pairs of shoulders were histologically examined. Results: The AC ligament was divided into 2 parts: a bundle at the superoposterior (SP) part and a bundle at the anteroinferior (AI) part of the joint. The well-developed SP bundle was consistent and ran obliquely at an average ± SD 30° ± 6° in relation to the AC joint surface, from the anterior part of the acromion to the posterior part of the distal clavicle. The joint inclination was 70° ± 12°, and a negative moderate correlation was found between the joint inclination and the ligament angle ( P = .02, r = −0.46). In comparison, the AI bundle was thin and narrow, and it could be categorized into 3 types according to its various configurations. Conclusion: The AC ligament could be separated into the SP bundle and the AI bundle. The SP bundle ran posteriorly toward the distal clavicle from the acromion at an average angle of 30° to the joint surface. Clinical Relevance: Anatomic reconstruction, based on the current findings in combination with findings regarding the coracoclavicular ligament, could facilitate improved outcome in the treatment of AC joint disruption.

The body plan along the anteroposterior axis and regional identities are specified by the spatiotemporal expression ofHoxgenes. Multistep controls are required for their unique expression patterns; however, the molecular mechanisms behind the tight control ofHoxgenes are not fully understood. In this study, we demonstrated that theLin28a/let-7reciprocal regulatory pathway is critical for vertebral specification.Lin28a−/−mice exhibited homeotic transformations of vertebrae which were caused by the global dysregulation of posteriorHoxgenes. The accumulation oflet-7-family microRNAs inLin28a−/−mice resulted in the reduction of PRC1 occupancy at theHoxcluster loci by targetingCbx2. Consistently, Lin28a loss in embryonic stem-like cells led to aberrant induction of posteriorHoxgenes, which was rescued by the knockdown oflet-7-family microRNAs. These results suggest thatLin28/let-7pathway is possibly involved in the modulation of the “Hoxcode” viaPolycombregulation during axial patterning in vertebrates.

SUMMARY Understanding the surgical anatomy is the key to reducing surgical invasiveness especially in the upper mediastinal dissection for esophageal cancer, which is supposed to have a significant impact on curability and morbidity. However, there is no theoretical recognition regarding the surgical anatomy required for esophagectomy, although the surgical anatomy in abdominal digestive surgery has been developed on the basis of embryological findings of intestinal rotation and fusion fascia. Therefore, we developed a hypothesis of a ‘concentric-structured model’ of the surgical anatomy in the upper mediastinum based on human embryonic development. This model was characterized by three factors: (1) a concentric and symmetric three-layer structure, (2) bilateral vascular distribution, and (3) an ‘inter-layer potential space’ composed of loose connective tissue. The concentric three-layer structure consists of the ‘visceral layer’, the ‘vascular layer’, and the ‘parietal layer’: the visceral layer containing the esophagus, trachea, and recurrent laryngeal nerves as the central core, the vascular layer of major blood vessels surrounding the visceral core to maintain the circulation, and the parietal layer as the outer frame of the body. The bilateral vascular distribution consists of the inferior thyroid arteries and bronchial arteries originating from the bilateral dorsal aortae in an embryo. This bilateral vascular distribution may be related to the formation of the proper mesentery of the esophagus and frequent lymph node metastasis observed in the visceral layer around recurrent laryngeal nerves. The three concentric layers are bordered by loose connective tissue called the ‘inter-layer potential space’. This inter-layer potential space is the fundamental factor of our concentric-structured model as the appropriate surgical plane of dissection. The peripheral blood vessels, nerves, and lymphatics transition between each layer, thereby penetrating this loose connective tissue forming the inter-layer potential space. Recurrent laryngeal nerves also transition from the vascular layer after branching off from the vagal nerves and then ascend consistently in the visceral layer. We investigated the validity of this concentric-structured model, confirming the intraoperative images and the surgical outcomes of thoracoscopic esophagectomy in a prone position (TSEP) before and after the introduction of this hypothetical anatomy model. A total of 226 patients with esophageal cancer underwent TSEP from January 2015 to December 2016. After the introduction of this model, the surgical outcomes in 105 patients clearly improved for the operation time of the thoracoscopic procedure (160 min vs. 182 min, P = 0.01) and the incidence of recurrent laryngeal nerve palsy (19.0% vs. 36.4%, P = 0.004). Moreover, we were able to identify the concentric and symmetric layer structure through surgical dissection along the inter-layer potential space between the visceral and vascular layers (‘viscero-vascular space’) in all 105 cases after introduction of the hypothetical model. The concentric-structured model based on embryonic development is clinically beneficial for achieving less-invasive esophagectomy by ensuring a theoretical understanding of the surgical anatomy in the upper mediastinum.

BACKGROUND The superficial musculoaponeurotic system (SMAS) is an anatomical structure involved in the facial ageing process. We aimed to evaluate the SMAS laxity using multi-detector row computed tomography (MDCT) as a diagnostic tool, and to analyse the relationship between SMAS laxity and age. METHODS Fifty-seven female subjects (aged 21-57 years) were enrolled in the study. The subjects were divided into two age groups: one below the mean age (Group Y, 30 subjects) and one over it (Group O, 27 subjects). The Posture Change (PC)-induced SMAS Laxity Index was measured using reconstructed CT images, and the relationship between the PC-induced SMAS Laxity Index and age was analysed. RESULTS The PC-induced SMAS Laxity Index was significantly larger in Group O than in Group Y. As well, a strong and significant positive correlation was detected between the PC-induced SMAS Laxity Index and age (r = 0.72; P

Background:Anatomical knowledge of the tarsal canal and sinus is still unclear owing to the complexity of the ligamentous structures within them, particularly the relationship with the capsules of the subtalar joints. The aim of this study was to examine the anatomical relationship between the fibrous tissues of the tarsal canal and sinus and the articular capsules of the subtalar joint.Methods:We conducted a descriptive anatomical study of 21 embalmed cadaveric ankles. For a macroscopic overview of the subtalar joint, we removed the talus in 18 ankles and separated the fibrous tissues from the surrounding connective tissues to analyze the layered relationship between the inferior extensor retinaculum (IER) and the subtalar joint capsule. Additionally, we histologically analyzed the tarsal canal and the medial and lateral sides of the tarsal sinus using Masson’s trichrome staining in 3 ankles.Results:The medial and intermediate roots of the IER and interosseous talocalcaneal ligament (ITCL) were located in the same layer and were connected to each other, between the capsules of the posterior talocalcaneal and talocalcaneonavicular joints. The intermediate root of the IER and the cervical ligament (CL) had adjacent attachments on the tarsal sinus, and synovial tissues originating from the joint capsules filled the remaining area in the tarsal canal and sinus.Conclusion:We determined that the tarsal canal and sinus tarsi contained 3 layered structures: the anterior capsule of the posterior talocalcaneal joint, including the anterior capsule ligament; the layer of ITCL and IER; and the posterior capsule of the talocalcaneonavicular joint, including the CL.Clinical Relevance:The results of this study may help with the understanding of the pathomechanism of subtalar instability and sinus tarsi syndrome, resulting in better treatment.

The primary divisions of the spinal nerve in the brown caiman characteristically show the following features: (1) the medial ramus was lies in the thoraco-lumbar and caudal regions, and (2) the first cervical and hypoglossal nerves form a single nerve complex from which the ventral and dorsal rami extend. Intramuscular injections of horseradish peroxidase (HRP) established the positions of motoneurons whose axons followed the primary rami. In the ventral horn of the thoracic and caudal spinal cord, the motoneurons of the medial ramus lie ventrally. These motoneurons lie between the epaxial and hypaxial motoneurons. At the spinomedullary junction, the pools of motoneurons innervating the infrahyoid, lingual, and dorsal muscles have a somatotopic organization similar to that observed in the thoraco-lumbar and caudal regions. Thus clear somatotopic organization of the motoneurons that innervate the axial musculature exists at all spinal levels. © 1994 Wiley-Liss, Inc.

Plastic surgery requires detailed knowledge of upper eyelid anatomy, but few authors have sufficiently described the specifics of upper eyelid nerve anatomy. This study aimed to provide a thorough description of sensory nerve anatomy in the upper eyelid and to propose considerations for upper eyelid surgery.Sixteen orbits were dissected from 16 fixed, adult human cadavers. Microscopically, the authors identified the main trunks of the infratrochlear, supratrochlear, and supraorbital nerves and all branches that projected toward the upper eyelid. The number, size, and distribution of nerve branches were recorded.The branches of the infratrochlear, supratrochlear, and supraorbital nerves covered a wide range in the upper eyelid. The mean numbers of branches per nerve were 1.6 ± 1.2, 3.2 ± 1.5, and 2.6 ± 1.4, respectively. The branches of the infratrochlear nerve were distributed throughout the medial area of the upper eyelid. Those of the supratrochlear nerve were distributed throughout the medial and central areas, and the palpebral branches of the supraorbital nerve were distributed throughout the central and lateral areas of the upper eyelid. The lateral branches of the supraorbital nerve and the cutaneous branches of the lacrimal nerve were distributed in the lateral region of the orbit.The authors show that upper eyelid sensation is transmitted mainly by the supratrochlear and supraorbital nerves, and the authors provide a map of the distribution of upper eyelid sensory nerves. This precise anatomical knowledge about upper eyelid sensory nerves will facilitate pain control and help minimize nerve injuries during surgery.

The anatomy of the rectourethralis muscle is essential for performing radical prostatectomy and proctectomy. The rectourethralis muscle is known to continue to the rectal wall posteriorly and to the membranous urethra anteriorly. However, the lateral extent of the rectourethralis muscle remains unclear. This study aimed to verify the hypothesis that the rectourethralis muscle laterally extends and directly adheres to the levator ani. Eight male cadavers were used for macroscopic dissection, and three male cadavers were used for immunohistological analysis using anti-smooth muscle and anti-skeletal muscle antibodies. The rectourethralis muscle laterally extended smooth muscle fibers both superoposteriorly and inferoanteriorly toward the levator ani. The smooth muscle fibers sandwiched the levator ani superoanteriorly and inferoanteriorly. A few smooth muscle fibers of the rectourethralis muscle inserted into the levator ani. This study clarified the spatial distribution of the rectourethralis muscle and its detailed positional relationship with the levator ani. The findings are valuable especially to urologists and anorectal surgeons for dissecting an optimal layer around the urethra and the rectum, and for avoiding rectal or urethral injuries during surgery. Clin. Anat. 31:1167-1176, 2018. © 2018 Wiley Periodicals, Inc.

The structure of the fascia in upper mediastinum has already been reported from gross anatomical viewpoints by Sarrazin. But it is necessary to understand meticulous anatomy for thoracoscopic or mediastinoscopic surgery. So herein, we investigate histologically the thin membranous structure made of dense connective tissues. Semi-sequential transverse sections of the mediastinum were obtained from three cadavers. Hematoxylin and eosin staining, Elastica van Gieson staining, and Masson trichrome staining were performed to identify the presence and location of the thin membranous structure made of dense connective tissues. The “visceral sheath” and “vascular sheath,” as previously described by Sarrazin, were observed histologically. These two thin membranous structures do not surround the esophagus and trachea cylindrically. In addition, the “visceral sheath” on the right side of the upper mediastinum was unclear in comparison to the left side. The “visceral sheath” (on the left side) gradually became unclear, and seemed to almost disappear; the esophagus was found to be very close to the thoracic duct on the caudal side of the bifurcation of the trachea. Although the left recurrent nerve was located inside the “visceral sheath” in all cadavers, the left recurrent nerve lymph nodes were located inside the “visceral sheath” in cadaver 1 and between the “visceral sheath” and “vascular sheath” in cadaver 3. The “visceral sheath” around the esophagus in the upper mediastinum was histologically demonstrated; however, the findings were not constant.

Background Although conventional Bankart repair has been the accepted procedure for traumatic anterior glenohumeral instability, the humeral avulsion of the glenohumeral ligament or an elongation of the capsule remains challenging to decide the appropriate treatment. The anatomical knowledge regarding the whole capsule of glenohumeral joint is necessary to accurately treat for the capsular disorders. The aims of the current study were to investigate the anatomical features of capsular attachment and thickness in a whole capsule of glenohumeral joint. Methods We used 13 shoulders in the current study. In 9 shoulders, we macroscopically measured the attachment widths of the capsulolabrum complex on the scapular glenoid, and the attachment widths of the capsule on the humerus in reference to the scapular origin of the long head of triceps brachii, and the humeral insertion of the rotator cuff tendons. We additionally used 4 cadaveric shoulders, which were embalmed using Thiel’s method, for the analysis of the thickness in a whole capsule by using micro-CT. Results The glenoidal attachment of the articular capsule appeared to have a consistent width except for the superior part of the origin of the long head of triceps brachii. On the humerus, the articular capsule was widely attached to areas without overlying rotator cuffs, with the widest width (17.3 ± 0.9 mm) attached to the axillary pouch. The inferior part of the capsule, which was consistently thicker than the superior part, continued to the superior part along the glenoid and humeral side edge. Conclusions The current study showed that the inferior part of the glenohumeral capsule had a wide humeral attachment from the inferior edge of the subscapularis insertion to the inferior edge of the teres minor insertion via the anatomical neck of the humerus, and the thickness of it was thicker than the superior part of the capsule.

Although studies support the clinical importance of the fibres from the horns of lateral meniscus (LM), few studies have investigated the detailed anatomy. This anatomic study was conducted to analyse the structural details of LM with special reference to (1) the attachment area of the fibres from the anterior and posterior horns and (2) the positional relationship between these fibres and the anterior cruciate ligament (ACL). A total of 24 cadaveric knees were used in the macroscopic investigation, and six knees were used in the histological investigation. Micro-computed tomography analysis was also performed to assess the anatomy of the posteriormost fibre from the posterior horn of LM. Based on the macroscopic investigations, the outer fibres from the anterior horn of LM extended to ACL and seemed to intermingle with ACL fibres. However, the histological investigations showed a distinct border between the fibres and ACL. The inner fibres from the anterior horn of LM attached to the lateral intercondylar tubercle serving as a lateral margin of ACL attachment. Fibres from the posterior horn of LM were separated into anterolateral and posteromedial crura which attached to the posterior aspect of the lateral and medial intercondylar tubercles, respectively. These two crura formed the posterior margin of the ACL attachment, except for the central part of ACL. The outer fibres from the anterior horn of LM adjoined ACL. The inner fibres from the anterior horn of LM and two crura from the posterior horn of LM formed the border of the attachment area of ACL. The distinctive fibre anatomy from LM could provide a surgical landmark during arthroscopic surgery.

Background: The developmental processes of the genital tubercle (GT), the anlage of the external genitalia, possess several developmental aspects, including GT outgrowth, urethral tube formation, and epithelial differentiation of the urethra. The GT comprises the mesenchyme derived from the lateral mesoderm, ectodermal epithelium, and endodermal epithelium (embryonic urethral epithelium). The three tissue layers develop the GT coordinately. Results: Around the initial stage of GT outgrowth (E11.5), FGF signaling was detected in the mesenchyme of the GT. FGF signaling was detected in the three tissue layers of the GT around the early stage of urethral formation (E13.5). Subsequently, FGF signaling was predominantly detected in the urethral epithelium (E14.5). Tissue-specific roles of FGF signaling in GT development were revealed by conditional Fgfr gene knockout approaches. Mesenchymal FGF signaling in the early-stage GT is required for its outgrowth. Ectodermal FGF signaling in the GT is required for the differentiation of the ectoderm and urethral epithelium at their junction to form the proper urethral tube. Endodermal FGF signaling in the GT is required for the stratification and cell adhesive characteristics of the urethral epithelium. Conclusions: The current study suggests that spatiotemporally regulated FGF signaling plays tissue-specific roles in multiple processes of external genitalia development. Developmental Dynamics 244:759–773, 2015. © 2015 Wiley Periodicals, Inc.

The use of mediastinal surgery for minimally invasive esophagectomy (MIE) has been proposed; however, this method is not performed as radical surgery because it has been thought to be impossible to perform complete upper mediastinal dissection, including the left tracheobronchial lymph nodes (106tbL). We herein describe a new method for performing complete dissection of the upper mediastinum. We developed a method for performing complete mediastinoscopic esophagectomy as radical surgery via the bilateral transcervical and transhiatal approach in 6 Thiel-embalmed human cadavers. The lower and middle mediastinal lymph nodes are dissected via the transhiatal approach. The dorsal side of the left recurrent nerve is dissected up to the aortic arch and left recurrent nerve lymph nodes (106recL) are dissected under pneumomediastinum. Next, the right recurrent nerve lymph nodes (106recR) are dissected. The cartilage of the left main bronchus is dissected and pushed downward, thereby obtaining a good view between the aortic arch and left main bronchus via the transhiatal approach. The 106tbL lymph nodes are dissected until the aortic arch is reached. Simultaneously, the lymph nodes are dissected via a right cervical incision. This method is termed the “cross-over technique.” We herein demonstrated that the upper mediastinal lymph nodes, including the 106tbL nodes, can be dissected using the bilateral transcervical and transhiatal approach under pneumomediastinum and named this method “mediastinoscopic esophagectomy with lymph node dissection” (MELD). MELD is therefore considered to be a useful modality based on our experience with Thiel-embalmed human cadavers.

Background The objective of this study was to evaluate the topographic relationship between the morphology of the greater tubercle and the insertion of the tendon of the infraspinatus. Materials and methods First, we defined an impression of the greater tubercle, which has not been recognized in classic textbooks, as the "lateral impression" and then measured the dimensions of the "lateral impression" of the greater tubercle in 71 samples of dry bone of humeri. Next, we examined 16 cadaveric humeri with rotator cuff tendons by micro–computed tomography to analyze the positional relationship between the lateral impression and the infraspinatus tendon. Results In all samples of dry bones, the lateral impression could be identified as a triangle shape. The lateral impression was composed of the border with the highest impression (mean, 6.3 mm), the border with the middle impression (mean, 5.0 mm), and the border with the lateral wall of the greater tubercle (mean, 8.5 mm). In all samples of humeri with rotator cuffs, we could confirm the lateral impression, and the border between the highest impression and the lateral impression corresponded to the anterior border of the insertion of the infraspinatus tendon. Conclusion We propose a new anatomic concept of the lateral impression that could enable the precise diagnosis of and facilitate repair techniques for infraspinatus tear, according to specific anatomic characteristics, by applying 3-dimensional computed tomography assessment preoperatively.

Background Patients with facial fracture or head and neck surgery sometimes suffer from infraorbital nerve injury. This injury results in severe hemilateral numbness in the midfacial area. The infraorbital nerve ends with two major branches; the infra nasal branch (INB) and superior labial branch (SLB). In this study, we assessed the feasibility of cross-nerve transfer of the INB and SLB based on a cadaver study. Methods The INB/SLB from a total 20 sides of 10 cadavers (2 men and 8 women; average age, 79.9 years) were dissected. The distribution patterns of the INB and SLB, the distance between the INB/SLB and the piriform aperture, and the shortest distance between the INB/SLB were estimated. Results Three distribution patterns of the INB and SLB were observed, that is type A (65%); only the INB is thick enough for a nerve transfer, type B (20%); only the SLB is thick enough for a nerve transfer, and a combination of types A and B (15%). The distance between the INB, SLB and the piriform aperture was on average 8.61 and 10.81 mm in each. The shortest distance between the INB and SLB was on average 11.34 ± 3.7 mm. Conclusions The INB and SLB existed in all the specimens and could be found approximately 1 cm below the piriform aperture. The average distance between the INB and SLB was approximately 11 mm. These results imply the feasibility of a cross-nerve transfer of the distal part of the infraorbital nerve.

The current study was conducted to clarify the morphology of the extraforaminal ligament (EFL) at the cervicothoracic junction and to compare the attachment of the EFL and the positional relation between the EFL and the spinal nerves, additionally to clarify the details within the connecting bundles at the cervicothoracic junction. The EFLs from the 4th cervical to the 4th thoracic vertebrae were dissected in 56 sides of 28 Japanese cadavers (11 males, 17 females). The range of age was 62.0–99.0 years. In addition, connecting bundles were analyzed by histological examination. Ventral to the spinal nerve, the capsulotransverse ligament (CTL), transforaminal ligament (TFL) and the ligament between the 7th cervical vertebra and the 1st rib were attached to the transverse process and rib. The EFL ventral to the 1st thoracic nerve was not observed in all sides. Dorsal to the spinal nerve, the anterior part of the superior costotransverse ligament (ASCL) and the ligament homologous to the ASCL were attached to the transverse process and rib. The superior radiating ligament (SRL) and the ligament homologous to the SRL were identified. The connecting bundles identified between the 7th cervical and the 1st thoracic nerve were histologically confirmed to consist of nerves and vessels. The EFLs at the cervicothoracic junction were found to be homologous. The connecting bundles were observed between the 7th cervical and the 1st thoracic nerve. Interestingly, the 1st thoracic level alone might be a unique level at the cervicothoracic junction.

Curative treatment of esophageal cancer requires meticulous superior mediastinal lymphadenectomy, in addition to esophagectomy, because superior mediastinal lymph node metastases are common in esophageal cancer. When preserving the tracheal branches of the left recurrent laryngeal nerve (RLN), good anatomical understanding is required for confirmation of the positional relationships between the courses of lymphatic vessels, lymph node distribution, and the left RLN and its tracheal branches. We performed a detailed anatomical examination of these relationships. Macroscopic anatomical observation and histological examination was performed on cadavers. In addition to hematoxylin and eosin staining, immunostaining using antipodoplanin antibody D2-40 (podoplanin) was performed to identify the lymphatic vessels. The tracheal branches of the left RLN were clearly observed, but no lymphatic vessels crossing the ventral or dorsal side of the branches were identified either macro-anatomically or histologically. No complex lymphatic network structure straddling the plane composed of tracheal branches of the left RLN was found in the left superior mediastinum. This suggests that dissection of the lymph nodes around the left RLN via the pneumomediastinum method using the left cervical approach may allow preservation of the tracheal branches of the left RLN by maintaining dissection accuracy.

Objective The aim of this study was to analyze the topographical structures of the muscles surrounding the Eustachian tube. Materials and methods We conducted macroscopic and histological studies of 24 halves of 12 heads from Japanese cadavers. Results The main findings were as follows: 1) the infero-lateral muscle bundles of the tensor veli palatini didn’t turn medially at the pterygoid hamulus but were distributed laterally and continuous with the buccinator; 2) the tensor veli palatini attached laterally to the membranous part of the Eustachian tube; 3) the superior pharyngeal constrictor was not only adjacent to the buccinator at the pterygomandibular raphe but also had muscular continuation with it laterally and 4) some bundles of the superior pharyngeal constrictor adhered with the palatine aponeurosis. Conclusion We believe that the cooperation of the muscles contributes to the dilating mechanism of the Eustachian tube, due to the complex topographical structures of the surrounding muscles: the tensor veli palatini, the levator veli palatini, the superior pharyngeal constrictor and the buccinator.

Background Finding appropriate recipient veins for free flap reconstruction in the adjacent temporal region is sometimes difficult when performing skull base or craniofacial reconstruction because there is a limited number of recipient veins in the temporal region compared with the neck. The authors used cadaver dissection to evaluate the viability of the middle temporal vein as a recipient vein in the temporal region. Methods The authors examined the characteristics and landmarks of the middle temporal vein in 60 sides of 30 cadavers. Its existence, caliber size, distribution pattern, and landmarks for dissection were measured. Results The middle temporal vein was located beneath the superficial layer of the deep temporal fascia and joined the main trunk of the superficial temporal vein. The vein was identified in all specimens, and its mean caliber was 1.88 mm. It was classified into four representative distribution patterns. According to the distribution pattern, the middle temporal vein provided one recipient vein without exception, and only 13 percent of middle temporal veins could provide two recipient veins. According to landmarks, the middle temporal vein runs approximately along the line between 52 mm lateral from the bony lateral canthus and 12 mm medial from the external auditory canal. The mean distance between the middle temporal vein and the temporal branch of the facial nerve was 13 mm. Conclusions The middle temporal vein can provide one recipient vein of adequate caliber in the temporal region. In addition, it can be easily localized, without damaging the facial nerve, by means of incision according to the landmarks described in this study.

Patients with a shoulder disorder often complain of pain on the anterior or lateral aspect of the shoulder. Such pain has been thought to originate from the suprascapular nerve. However, taking into consideration the distinctive course of the axillary nerve, the axillary nerve is likely to supply branches to the structure around the shoulder joint. This study was conducted to clarify the division, course, and distribution of the branches which originate from the axillary nerve and innervate structures around the shoulder joint. The division, course, and distribution of the branches which originate from the axillary nerve and innervate structures around the shoulder joint were examined macroscopically by dissecting 20 shoulders of 10 adult Japanese cadavers. The thin branches from the anterior branch of the axillary nerve were distributed to the subacromial bursa and the area around the long head of the biceps tendon. The branches from the main trunk of the axillary nerve or the branch to the teres minor muscle were distributed to the infero-posterior part of the shoulder joint. The pain on the anterior or lateral aspect of the shoulder, which has been thought to originate from the suprascapular nerve, might be related to the thin branches which originate from the axillary nerve and innervate the subacromial bursa and the area around the long head of the biceps tendon. These results would be useful to consider the cause of the shoulder pain or to prevent the residual pain after the biceps tenodesis.

The cloaca is temporally formed and eventually divided by the urorectal septum (URS) during urogenital and anorectal organ development. Although congenital malformations, such as anorectal malformations (ARMs), are frequently observed during this process, the underlying pathogenic mechanisms remain unclear. β-Catenin is a critical component of canonical Wnt signaling and is essential for the regulation of cell differentiation and morphogenesis during embryogenesis. The expression of β-catenin is observed in endodermal epithelia, including URS epithelia. We modulated the β-catenin gene conditionally in endodermal epithelia by utilizing tamoxifen-inducible Cre driver line (Shh(CreERT2)). Both β-catenin loss- and gain-of-function (LOF and GOF) mutants displayed abnormal clefts in the perineal region and hypoplastic elongation of the URS. The mutants also displayed reduced cell proliferation in the URS mesenchyme. In addition, the β-catenin GOF mutants displayed reduced apoptosis and subsequently increased apoptosis in the URS epithelium. This instability possibly resulted in reduced expression levels of differentiation markers, such as keratin 1 and filaggrin, in the perineal epithelia. The expression of bone morphogenetic protein (Bmp) genes, such as Bmp4 and Bmp7, was also ectopically induced in the epithelia of the URS in the β-catenin GOF mutants. The expression of the Msx2 gene and phosphorylated-Smad1/5/8, possible readouts of Bmp signaling, was also increased in the mutants. Moreover, we introduced an additional mutation for a Bmp receptor gene: BmprIA. The Shh(CreERT2/+); β-catenin(flox(ex3)/+); BmprIA(flox/-) mutants displayed partial restoration of URS elongation compared with the β-catenin GOF mutants. These results indicate that some ARM phenotypes in the β-catenin GOF mutants were caused by abnormal Bmp signaling. The current analysis revealed the close relation of endodermal β-catenin signaling to the ARM phenotypes. These results are considered to shed light on the pathogenic mechanisms of human ARMs.

Quantitative and qualitative kinematic analyses of subacromial impingement by 1.2T open MRI were performed to determine the location of impingement and the involvement of the acromioclavicular joint. In 20 healthy shoulders, 10 sequential images in the scapular plane were taken in a 10-s pause at equal intervals from 30° to maximum abduction in neutral and internal rotation. The distances between the rotator cuff (RC) and the acromion and the acromioclavicular joint were measured. To comprehend the positional relationships, cadaveric specimens were also observed. Although asymptomatic, the RC came into contact with the acromion and the acromioclavicular joint in six and five cases, respectively. The superior RC acted as a depressor for the humeral head against the acromion as the shoulder elevated. The mean elevation angle and distance at the closest position between the RC and the acromion in neutral rotation were 93.5° and 1.6 mm, respectively, while those between the RC and the acromioclavicular joint were 86.7° and 2.0 mm. When comparing this distance and angle, there was no significant difference between the RC to the acromion and to the acromioclavicular joint. The minimum distance between the RC and the acromion was significantly shorter than that between the greater tuberosity and the acromion. The location of RC closest to the acromion and the acromioclavicular joint differed significantly. Although asymptomatic, contact was found between the RC and the acromion and the acromioclavicular joint. The important role of the RC to prevent impingement was observed, and hence, dysfunction of the RC could lead to impingement that could result in a RC lesion. The RC lesions may differ when they are caused by impingement from either the acromion or the acromioclavicular joint.

Purpose To identify the unique anatomical characteristic of the extensor carpi radialis brevis (ECRB) origin and points of differentiation from other extensors and to clarify the specific relationship of the ECRB to the underlying structures. Methods We studied the origin of each extensor macroscopically for its muscular and tendinous parts; to identify the relationship between the ECRB origin and the deeper structures, we also examined the attachment of the joint capsule under the ECRB origin. Results The ECRB simply originated as a tendon without any muscle, whereas other extensors originated as a mixture of tendon and muscle. At the anterior part of the ECRB origin, the thin attachment of the joint capsule (average width, 3.3 mm) lay deep to the ECRB and was distinct. However, at the posterodistal portion, the joint capsule, annular ligament, and supinator were intermingled and originated as a single wide sheet from the humerus (average width, 10.7 mm). Conclusions The anterior part of the ECRB origin was delicate, because the ECRB origin was purely tendinous, and the attachment of the articular capsule was thin compared with that of the posterodistal attachment. This thin attachment could be an initial factor leading to the development of lateral epicondylitis. Clinical relevance The results of the current study may enhance magnetic resonance imaging understanding and may help clarify the etiology of the lateral epicondylitis.

The minute details of the structure of the anal canal are still not well understood. The complex structural configuration of the muscles, ligaments and raphes remains unclarified. This study was undertaken to determine the precise structure of the posterior part of the anal canal and to facilitate an understanding of previous studies. For macroscopic examination, 14 right pelvic halves from 14 Japanese cadavers were used. Observation and dissection were performed from the median plane. In the histological examination, six left pelvic halves were used. The sections of the posterior parts of the anal canal were stained with hematoxylin and eosin, Elastic van Gieson, anti-smooth actin antibody and anti-skeletal myosin antibody. We identified the following muscles arranged from the internal side to the external side: internal anal sphincter, longitudinal muscle (LM), external anal sphincter (EAS) and levator ani muscle (LAM). Two different types of conformation of the posterior part of the anal canal were found, each bearing a different shape of EAS. In both types, LM penetrated the inferior part of EAS. After penetrating EAS, some fibers of LM ran posterosuperiorly and attached to the “the posterior fibers” which reach the dorsal side of the coccyx. We defined and labeled the connective tissues between the anal canal and coccyx on the basis of their relative position to LAM. Based on a comparison of the two types of the posterior part of the anal canal, we propose that there are two phases due to constriction and relaxation of LM.

Precise clinical knowledge of liver anatomy is required to safely perform a hepatectomy, for both open and laparoscopic surgery. At the 19th meeting of the Japanese Research Society of Clinical Anatomy (JRSCA), we conducted special symposia on essential issues of liver surgery, such as the history of hepatic segmentation, the glissonean pedicle approach, application of 3-D imaging simulation and fluorescent imaging using indocyanine green solution, a variety of segmentectomies including caudate lobectomy, the associating liver partition and portal vein embolization for stage hepatectomy and harvesting liver grafts for living donor liver transplantation. The present review article provides useful information for liver surgeons and anatomic researchers.

Background The teres minor muscle is a focused topic on the treatment of massive rotator cuff tears and reverse total shoulder arthroplasty. Its precise anatomy and function have not been completely investigated. The purposes of this study were to anatomically investigate the muscle and analyze electromyographic (EMG) activities during shoulder motion. Methods This anatomic study used 20 shoulders from deceased donors (mean age, 75.0 years). EMG data were recorded from 10 healthy volunteers (mean age, 21.7 years) during flexion, abduction, and external rotations at 0° of abduction, at 90° of abduction, and at 90° of flexion in their dominant arms synchronized with a computerized 3-dimensional motion analysis system. Results The muscle in all specimens consisted of 2 distinct muscular bundles: the upper and lower portions. The upper portion attached to the round area of the greater tuberosity, and the lower portion inserted into the linear shaped area. Both portions were independent in their origins, insertions, and innervation. The muscle engaged force during each shoulder motion. EMG activities of abduction and the 3 forms of external rotation were similar. Maximal voluntary contraction in the 3 forms of external rotation was 32% in maximum external rotation in the neutral position, 25% in flexion, and 40% in abduction. Conclusions The teres minor consists of independent upper and lower portions. The muscle engages force in all ranges of 5 shoulder motions, and maximum external rotation in abduction is a reliable method to evaluate potential activity of the muscle.

It is relatively well accepted that the long head of the biceps femoris and the semitendinosus both originate from the ischial tuberosity as a common tendon. However, it is also widely known that the biceps femoris is consistently injured more than the semitendinosus. The purpose of this study was to examine the origins of the hamstring muscles, to find an anatomic basis for diagnosis and treatment of injuries of the posterior thigh regions.Twenty-eight hips of fourteen adult Japanese cadavers were used in this study. In twenty hips of ten cadavers, the positional relationships among the origins on the ischial tuberosity were examined. In eight hips of four cadavers, histological examination of the origins of the hamstrings was also performed.The origin of the long head of the biceps femoris adjoined that of the semitendinosus. In the proximal regions of these muscles, the long head consisted of the tendinous part; however, the semitendinosus mainly consisted of the muscular part. Some of the fibers of the biceps tendon extended to fuse with the sacrotuberous ligament. The semimembranosus muscle broadly originated from the lateral surface of the ischial tuberosity.The origins of the long head of the biceps femoris and the semitendinosus are found to be almost independent, and the tendon of the long head is partly fused with the sacrotuberous ligament. The high incidence of injuries to the long head of the biceps femoris could be explained by these anatomical configurations.

Background To date, there are no studies about the attachment of the articular capsule of the superior shoulder joint. The aim of this study was to measure the width of the attachment of the articular capsule on the humerus, and to clarify the anatomy and the relationship to the footprint of the rotator cuff. Methods The attachment of the articular capsule on the greater tuberosity was exposed. The width of the attachment of the capsule and the footprint of the rotator cuff were measured. Results The maximum capsular width was located at the border between the infraspinatus and the teres minor, and measured 9.1 mm. The minimum capsular width was 3.5 mm, and it was located at 10.9 mm posterior to the anterior margin of the greater tuberosity and 1.5 mm anterior to the posterior margin of the supraspinatus. Conclusion Prior studies have overestimated the rotator cuff footprint width due to the lack of discrimination between the actual cuff insertion and capsule. The attachment of the articular capsule of the shoulder joint occupied a substantial area of the greater tuberosity. In particular, at the border between the infraspinatus and the teres minor, the very thick attachment of the articular capsule compensated for the lack of attachment of muscular components. The thinnest point of the articular capsule was 11 mm posterior to the anterior margin of the greater tuberosity and very close to the posterior edge of the tapered insertion of the supraspinatus, which could contribute to the etiology of degenerative rotator cuff tears.

When we assess anatomical problems and the safety and effectiveness for performing a difficult surgical procedure or planning novel surgical approaches, preoperative human dissections are very helpful. However, embalming with the conventional formaldehyde method makes the soft tissue of the cadaver harder than that of a living body. Therefore, the cadaver embalmed with conventional formaldehyde is not appropriate for dissections when assess surgical approaches. Thiel's method is a novel embalming technique, first reported by W. Theil in 1992. This method can preserve color and softness of the cadaver without risk of infections. We have used cadavers embalmed with Thiel's method for preoperative assessments and have confirmed the usefulness of this method especially for the prevention of complications or in assessing surgical approaches. The cadaver embalmed with this method has several advantages over other embalming methods and it might be also useful for the developments of new surgical devices or evaluation of a surgeon's skill.

【目的】経絡経穴とその周囲構造物との位置関係を形態学的に明らかにする一環として、 下肢後面における経穴について検討した。 【方法】東京医科歯科大学解剖学実習体３体６側を使用した。 下肢後面における足の太陽膀胱経に刺鍼を施し、 その部位を中心とした局所解剖を行った。 【結果】１． 承扶・殷門は、 大腿二頭筋の表層を走行する後大腿皮神経および深層を走る坐骨神経より内側に位置した。 ２.浮ゲキ・委陽は、 大腿二頭筋停止腱の内側縁に沿って総腓骨神経の走路に位置した。 ３.委中・合陽・承筋・承山・飛揚・フ陽・崑崙・申脈は、 内側腓腹皮神経、 腓腹神経およびは小伏在静脈に沿って位置した。 ４. 委中・合陽・承筋・承山は、 深層では脛骨神経および膝窩動脈、 後脛骨動脈に沿って位置した。 【結論】１.後大腿皮神経および坐骨神経は承扶・殷門より外側を走行する傾向が強く、 これら神経への刺鍼は承扶・殷門より外側に施す必要性が示唆された。 ２． 下腿後面の腓腹神経および小伏在静脈は、 末梢に向かうにつれて経穴に沿う傾向が強くなる。 ３.下腿後面の深層を走る脛骨神経への刺鍼は、 委中・合陽・承筋・承山が効果的であることが示唆された。

Patients reporting that their symptoms of urinary incontinence have decreased after total hip arthroplasty can be encountered in orthopedic practice. In this questionnaire-based study, we prospectively evaluated the symptoms of urinary incontinence before and after total hip arthroplasty. The International Consultation on Incontinence Questionnaire-Short Form was used to prospectively evaluate these symptoms in 189 consecutive female patients undergoing total hip arthroplasty. The patients were asked to fill in a questionnaire before and 3 months after surgery. A decrease in the International Consultation on Incontinence Questionnaire-Short Form score of ≥1 point was defined as an improvement, whereas an increase of ≥1 point was defined as worsening. A total of 81 (43%) patients reported urinary incontinence before total hip arthroplasty. At 3 months after surgery, symptoms of urinary incontinence were improved in 64% of these patients, remained unchanged in 32% and worsened in 4%. Mean International Consultation on Incontinence Questionnaire-Short Form score in patients with urinary incontinence before surgery significantly improved from 6.0 to 3.5 (P = 0.0002). These findings suggest a relationship between hip joint function and pelvic floor function, and consequently a hip dysfunction-related urinary incontinence.

Purpose To identify the layered relationship anatomically between the musculotendinous structures of the adductor pollicis, the ulnar collateral ligament, and the capsule of the metacarpophalangeal joint in terms of understanding the pathomechanism of a Stener lesion. Methods We macroscopically analyzed 37 cadaveric thumbs to identify the intramuscular tendon of the adductor pollicis and bony attachments of the joint capsule including the ulnar collateral ligament. In addition, we histologically analyzed 3 thumbs and made a 3-dimensional image of 3 other thumbs, using micro-computed tomography. Results The adductor pollicis has 3 components of an intramuscular tendon (dorsal, palmar, and distal), which connect to form a lambda shape. The dorsal part inserts into the joint capsule dorsal to the ulnar sesamoid. The palmar part inserts into the ulnar sesamoid. The distal part inserts into the lateral tubercle of the proximal phalanx. The thickened and cord-like part of the joint capsule, which has generally been referred to as the proper ulnar collateral ligament, has a distinct bony attachment on the proximal slope of the lateral tubercle of the proximal phalanx separate from the adductor pollicis insertion. Conclusions Of the 3 components of the intramuscular tendon of the adductor pollicis muscle, the dorsal part inserted into not only the aponeurosis but also the joint capsule. Clinical relevance The results of the current study suggest the anatomic basis for a possible pathomechanism of the Stener lesion.

Infraspinatus muscle atrophy is sometimes observed in rotator cuff tears that appear to involve only the supraspinatus tendon. The goal of this study was to evaluate infraspinatus muscle atrophy as a function of the sagittal extent of tears, using magnetic resonance imaging. Forty-three patients (45 shoulders) were enrolled, including 23 men and 20 women with a mean age of 60 years. Patients were divided into 4 groups reflecting the sagittal extent of their tears: 16 shoulders with intact cuff (group A), 8 tears localized to the anterior half of the superior facet (group B), 10 tears extending to the posterior half of the superior facet (group C), and 11 tears extending to the middle facet (group D). The infraspinatus muscle was divided into 4 compartments using proximal muscular slices in oblique sagittal images; muscle atrophy in each compartment was graded on a scale of I to IV. Within each compartment, differences in degree of atrophy between the 4 groups were statistically tested. No shoulders in groups A and B had more than grade II atrophy in all compartments. However, grade III and IV atrophy was observed in group C in the anterosuperior compartment and in group D in all compartments. Considering the new anatomical finding that the infraspinatus inserts into the posterior portion of the superior facet as well as the middle facet, infraspinatus muscle atrophy in group C patients may have resulted from infraspinatus tendon involvement in this type of tear.

【目的】WHOにより標準経穴部位(361穴, 2006)の合意が成され、 それに伴って秩辺の取穴場所の変更が行われた。 新旧両秩辺とその周囲構造物との位置関係および腰痛に対する治療部位としての坐骨神経への刺鍼点について検討した。 【方法】東京医科歯科大学解剖学実習体3体6側を使用した。 殿部および大腿後面における太陽膀胱経に、 WHOの取穴方法に従って刺鍼を施し、 その部位を中心とした局所解剖を行った。 【結果】１.新秩辺(WHO, 2006)は、 後大腿皮神経、 下殿神経・動脈、 坐骨神経が出現する梨状筋下孔の近傍に位置した。 ２.旧秩辺は上殿神経・動脈が出現する梨状筋上孔の近傍に位置した。 ３.殿部および大腿後面での坐骨神経への刺鍼部位として、 (1)坐骨神経形成根部、 (2)梨状筋下孔、 (3)仙尾連結と大転子を結ぶ線上の外側1/3点、 (4)坐骨結節と大転子を結ぶ線上の中点、 (5)承扶の約1cm外側の地点、 (6)殷門の外側、 大腿二頭筋筋腹の内側半部、 が挙げられた。 【結論】１． 新旧両秩辺とも殿部および大腿後面にとって重要な神経・血管の近傍に位置し、 種々の病的症状に対する有効な刺鍼部位と考えられる。 ２. 殿部および大腿後面での坐骨神経に対する刺鍼部位として、 走行経路より６カ所が示唆された。

【目的】骨盤内臓の疾患に対する重要な治療点としての八リョウ穴と骨盤神経叢の構成および臓側枝との位置関係を検討した。 【方法】東京医科歯科大学大学院臨床解剖学分野所蔵の実習体５体を使用し、 実体顕微鏡下で、 骨盤神経叢の構成および臓側枝の分岐形態と八リョウ穴との位置関係を精査した。 【結果】１． 骨盤神経叢を構成する交感神経成分の下腹神経は第２および第３腰内臓神経が恒常的に参加する上下腹神経叢から起こり、 骨盤神経叢の後上角に入る。 副交感神経成分の骨盤内臓神経は第２～第４仙骨神経前枝から起始し、 骨盤神経叢の後下角に入る。 陰部神経および肛門挙筋神経とは共通幹を形成する傾向が強い。 ２. 骨盤神経叢から起こり骨盤内臓に分布する臓側枝は均一に起始するのではなく、 I～IV群に分かれる傾向が強い。 特に、 III群は排尿・性機能に深い関わりを持つ。 【結論】１． 八リョウ穴への刺鍼では、 骨盤内臓神経が恒常的に起こる第３および第４仙骨神経前枝に直接刺激が可能である中リョウ (BL33) および下リョウ (BL34) が骨盤内臓の機能に影響を及ぼすことが示唆される。 ２. 八リョウ穴への深鍼では、 刺入鍼は直腸の側縁に達するため正中方向への刺鍼には注意を要する。