Determination of HIF-1α degradation pathways via modulation of the propionyl mark.

The hypoxia-inducible factor-1α (HIF-1α) is a key regulator of hypoxic stress under physiological and pathological conditions. HIF-1α protein stability is tightly regulated by the ubiquitin-proteasome system (UPS) and autophagy in normoxia, hypoxia, and the tumor environment to mediate the hypoxic response. However, the mechanisms of how the UPS and autophagy interplay for HIF-1α proteostasis remain unclear. Here, we found a HIF-1α species propionylated at lysine (K) 709 by p300/CREB binding protein (CBP). HIF-1α stability and the choice of degradation pathway were affected by HIF-1α propionylation. K709-propionylation prevented HIF-1α from degradation through the UPS, while activated chaperon-mediated autophagy (CMA) induced the degradation of propionylated and nonpropionylated HIF-1α. CMA contributed to HIF-1α degradation in both normoxia and hypoxia. Furthermore, the pan-cancer analysis showed that CMA had a significant positive correlation with the hypoxic signatures, whereas SIRT1, responsible for K709-depropionylation correlated negatively with them. Altogether, our results revealed a novel mechanism of HIF-1α distribution into two different degradation pathways. [BMB Reports 2023; 56(4): 252-257].

Transepithelial channels for leukocytes in the junctional epithelium.

BACKGROUND AND OBJECTIVES: The junctional epithelium (JE) has been recognized as a defensive organ rich in polymorphonuclear leukocytes (PMNs). However, the migration of PMNs through the JE has not been clearly documented. For mucosal defense, PMNs migrate outwards over the epithelium to defend the intestinal or respiratory tract on the epithelial surface. With this background, the present study investigated whether there is any structural evidence showing the transepithelial migration of PMNs through the JE in gingival mucosa. METHODS: Three-dimensional modeling of gingiva surrounding mouse molars at varying ages was performed by array tomography. Images of the serial sections for array tomography at the 800 nm thickness were obtained using back scattered electron (BSE) detector equipped in the field-emission scanning electron microscopy (FESEM). Expressions of neutrophil marker or CD47 were immunohistochemically examined on the frozen sections. RESULTS: Array tomography using FESEM and 3-dimensional modeling clearly showed that a system of epithelial channels developed between keratinocytes and generally ran along the long axis of the JE. Most PMNs were found inside the channels, rather than being scattered throughout the JE. The channels could be traced from the base of the JE to the bottom of the gingival sulcus, although some channels were fragmented and interrupted with short intercellular gaps. CONCLUSIONS: These findings suggest that the JE may be an organ for transepithelial migration of PMNs to the bottom of the gingival sulcus through epithelial channels, as occurs in the epithelial lining of other organs such as the intestinal or respiratory tract.

Classification of the interosseous tarsometatarsal ligaments of the foot.

BACKGROUND: The aim of this study was to clarify the anatomical features of the interosseous tarsometatarsal ligaments of foot and to classify their types based on the combinations of their ligamentous components. METHODS: Fifty feet from 27 adult Korean cadavers were dissected. RESULTS: The interosseous tarsometatarsal ligaments were observed in the first, second, and third cuneometatarsal joint spaces. The interosseous tarsometatarsal ligament of the first cuneometatarsal space consistently connected the medial cuneiform and the second metatarsal, and was accompanied by one or two accessory ligaments above (34%) and/or below (6%) the Lisfranc ligament. The interosseous tarsometatarsal ligaments of the second and third cuneometatarsal joint spaces comprised seven and five components, and were classified into five and three types depending on the number and combination of the components, respectively. CONCLUSIONS: These results are expected to advance the current knowledge on the tarsometatarsal joint and provide helpful information for more accurate and successful diagnosis and treatment of lesions at this joint.

The three muscle layers in the pyloric sphincter and their possible function during antropyloroduodenal motility.

This study was conducted to determine the muscular arrangement of the human pyloric sphincter using a comprehensive approach that involved microdissection, histology, and microcomputed tomography (micro-CT). The stomachs of 80 embalmed Korean adult cadavers were obtained. In all specimens, loose muscular tissue of the innermost aspect of the sphincter wall ran aborally, forming the newly found inner longitudinal muscle bundles, entered the duodenum, and connected with the nearby circular bundles. In all specimens, approximately one-third of the outer longitudinal layer of the sphincter entered its inner circular layer, divided the circular layer into several parts, and finally connected with the circular bundles. Anatomical findings around the sphincter were confirmed in micro-CT images. The sphincter wall comprised three layers: an inner layer of longitudinal bundles, a middle layer of major circular and minor longitudinal bundles, and an outer layer of longitudinal bundles. The stomach outer longitudinal bundles were connected to the sphincter circular bundles. The inner longitudinal bundles of the sphincter were connected to the adjacent circular bundles of the duodenum.

Elemental Sub-Lattice Occupation and Microstructural Evolution in γ/γ' Co-12Ti-4Mo-Cr Alloys.

We report on comparative atom probe tomography investigations of γ/γ'-forming Co­12Ti­4Mo­Cr alloys. Moderate additions of Cr (2 and 4 at%) reduced the γ/γ' lattice misfit and increased the γ' volume fraction of a Co­12Ti­4Mo alloy significantly. These microstructural changes were accompanied by changes in the elemental partitioning between γ and γ' and site-occupancy in γ'. Spatial distribution maps revealed that Mo occupied both Co and Ti sub-lattice sites in γ'. In agreement with the experimental data, thermodynamic calculations predicted a stronger tendency for Mo to occupy the Co-sites than for Cr and an increase in Cr fraction on the Ti-sites with increasing Cr content.

Newly-found channels in the interatrial septum of the heart by dissection, histologic evaluation, and three-dimensional microcomputed tomography.

A minute thrombus can pass through a small type of interatrial communication, which can result in a stroke or transient ischemic attack and several associated symptoms. This study sought to investigate a new type of interatrial communication. Thirty-one hearts from embalmed adult cadavers were investigated. Each interatrial channels (IACs) was classified as either an open or obstructed channel according to the connection of each hole on the right and left surfaces of the interatrial septum. Open channels were found in two specimens (6.5%). Both open and obstructed IACs followed tortuous courses through the interatrial septum. On the right surface of the interatrial septum, the hole was usually found adjacent to the left border of the interatrial septum between the opening of the superior vena cava into the right atrium and the superior margin of the fossa ovalis. Conversely, holes on the left surface of the interatrial septum were usually found in the upper and middle parts adjacent to the left border of the interatrial septum. This novel finding is expected to support our understanding of the onset of possible symptoms such as stroke in the absence of classical atrial septal defects.

Heights and spatial relationships of the facial muscles acting on the nasolabial fold by dissection and three-dimensional microcomputed tomography.

The aim of this study was to clarify the heights and spatial relationships of the facial muscles acting on the nasolabial fold (NLF) by dissection and three-dimensional microcomputed tomography for use in aesthetic treatments. This study used 56 specimens from 34 embalmed adult Korean. A reference line (RF) was set to imitate the NLF after removing the skin, from the superior point of the alar facial crease to the lateral point of the orbicularis oris muscle at the level of the corner of the mouth. The heights and spatial relationships of the facial muscles along the RF could be categorized into five main patterns. The dominant pattern was that the levator labii superioris alaeque nasi muscle (LLSAN), levator labii superioris muscle (LLS), zygomaticus minor muscle (Zmi), and zygomaticus major muscle (Zmj) were on the medial third, medial half, middle third, and lateral third of the RF, respectively. In micro-CT imaging, beneath the skin of the medial half of the NLF, the LLSAN and Zmi fibers inserted into the dermis of the NLF and adjacent to the NLF. Beneath the skin of the middle third of the NLF, the Zmi fibers were found before the muscle inserted into the dermis of the NLF and adjacent to the NLF. Beneath the skin of the lateral third of the NLF, the lateral margin of the orbicularis oris muscle and some Zmj fibers were found at the location of the NLF. The present study utilized dissections and micro-CT to reveal the general pattern and variations of heights and spatial relationships of the facial muscles passing beneath the NLF. These findings will be useful for understanding which muscles affect specific parts of NLFs with various contours, for reducing the NLF in aesthetic treatments, and for reconstructing the NLF in cases of facial paralysis.

Longitudinal muscular column in the prostatic urethral wall: Its form, shape, and possible function based on mathematical simulation in ejaculation.

BACKGROUND: The shape and function of the longitudinal muscular column (LMC) of the prostate have not been established in detail. The present study was undertaken to elucidate the roles of the LMC of the posterior wall of the prostatic urethra (PSU) in the emission phase of ejaculation by investigating the form and muscular arrangement of the LMC. METHODS: Prostates and urinary bladders were obtained from 14 Korean adult cadavers. Nine specimens were histologically analyzed using hematoxylin and eosin, Masson's trichrome, and Verhoeff-van Gieson staining. Two specimens were scanned using microcomputed tomography (micro-CT), and all scanned images were reconstructed into a three-dimensional model. RESULTS: At the proximal level of the prostate, the ejaculatory ducts (EDs) and prostatic utricle (PU) together were surrounded by circular smooth-muscle fibers. However, at the seminal colliculus (SC) where the EDs and PU opened, they were mainly surrounded by an abundance of longitudinal fibers. The longitudinal fibers posterior to the EDs and PU formed a distinctive LMC in the posterior urethral wall. In histologic sections and micro-CT images, the LMC extended distally from the level of the SC to the level of the membranous urethra (MBU). We simulated a potential mechanism of LMC using a mathematical model of its movements. CONCLUSIONS: Comprehensive analyses based on in-depth assessment of histologic characteristics and micro-CT images demonstrated extension of the LMC from the level of the SC to the level of the MBU, enabling a better understanding of ejaculation physiology involving the LMC. These results suggest that the LMC in the posterior wall of the PSU is a critical component of ejaculation by facilitating the ejection of seminal vesicle fluid into the PSU via well-coordinated contractions.

Vitamin D maintains E-cadherin intercellular junctions by downregulating MMP-9 production in human gingival keratinocytes treated by TNF-α.

PURPOSE: Despite the well-known anti-inflammatory effects of vitamin D in periodontal health, its mechanism has not been fully elucidated. In the present study, the effect of vitamin D on strengthening E-cadherin junctions (ECJs) was explored in human gingival keratinocytes (HGKs). ECJs are the major type of intercellular junction within the junctional epithelium, where loose intercellular junctions develop and microbial invasion primarily occurs. METHODS: HOK-16B cells, an immortalized normal human gingival cell line, were used for the study. To mimic the inflammatory environment, cells were treated with tumor necrosis factor-alpha (TNF-α). Matrix metalloproteinases (MMPs) in the culture medium were assessed by an MMP antibody microarray and gelatin zymography. The expression of various molecules was investigated using western blotting. The extent of ECJ development was evaluated by comparing the average relative extent of the ECJs around the periphery of each cell after immunocytochemical E-cadherin staining. Vitamin D receptor (VDR) expression was examined via immunohistochemical analysis. RESULTS: TNF-α downregulated the development of the ECJs of the HGKs. Dissociation of the ECJs by TNF-α was accompanied by the upregulation of MMP-9 production and suppressed by a specific MMP-9 inhibitor, Bay 11-7082. Exogenous MMP-9 decreased the development of ECJs. Vitamin D reduced the production of MMP-9 and attenuated the breakdown of ECJs in the HGKs treated with TNF-α. In addition, vitamin D downregulated TNF-α-induced nuclear factor kappa B (NF-κB) signaling in the HGKs. VDR was expressed in the gingival epithelium, including the junctional epithelium. CONCLUSIONS: These results suggest that vitamin D may avert TNF-α-induced downregulation of the development of ECJs in HGKs by decreasing the production of MMP-9, which was upregulated by TNF-α. Vitamin D may reinforce ECJs by downregulating NF-κB signaling, which is upregulated by TNF-α. Strengthening the epithelial barrier may be a way for vitamin D to protect the periodontium from bacterial invasion.

First Evidence for Mechanism of Inverse Ripening from In-situ TEM and Phase-Field Study of δ' Precipitation in an Al-Li Alloy.

In-situ TEM investigation of aging response in an Al-7.8 at.% Li was performed at 200 °C up to 13 hours. Semi-spherical δ' precipitates growing up to an average radius of 7.5 nm were observed. The size and number of individual precipitates were recorded over time and compared to large-scale phase-field simulations without and with a chemo-mechanical coupling effect, that is, concentration dependence of the elastic constants of the matrix solid solution phase. This type of coupling was recently reported in theoretical studies leading to an inverse ripening process where smaller precipitates grew at the expense of larger ones. Considering this chemo-mechanical coupling effect, the temporal evolution of number density, average radius, and size distribution of the precipitates observed in the in-situ experiment were explained. The results indicate that the mechanism of inverse ripening can be active in this case. Formation of dislocations and precipitate-free zones are discussed as possible disturbances to the chemo-mechanical coupling effect and consequent inverse ripening process.

Variations of the plantar tarsometatarsal ligaments.

This study investigated the morphological variations of the plantar tarsometatarsal ligaments of the foot by classifying them based on their ligamentous components. Fifty embalmed feet from 27 adult Korean cadavers were used. The plantar tarsometatarsal ligaments comprised nine components (medial cuneiform-first metatarsal, pCn1-M1; medial cuneiform-second metatarsal, pCn1-M2; medial cuneiform-second and third metatarsals, pCn1-M2,3; median cuneiform-second metatarsal, pCn2-M2; lateral cuneiform-third metatarsal, pCn3-M3; lateral cuneiform-fourth metatarsal, pCn3-M4; lateral cuneiform-third and fourth metatarsals, pCn3-M3,4; cuboid-fourth metatarsal, pCb-M4; and cuboid-fifth metatarsal, pCb-M5). pCn1-M2 was newly observed in the present study. The number of the bands composing the ligament was one in the pCn1-M2, pCn2-M2, pCn3-M3, and pCn3-M4 components, and one or two in the pCn1-M1, pCn1-M2,3, pCn3-M3,4, pCb-M4, and pCb-M5 components. The plantar tarsometatarsal ligaments were classified into five types based on the combination of their components. The pCn1-M1, pCn1-M2,3, and pCn2-M2 components were consistently observed in types I-IV (88%), along with pCn3-M3,4 in type I, pCn3-M4 and pCb-M5 in type II, and pCn3-M3 in type IV. In type V (12%), the pCn1-M1 and pCb-M5 components were consistently present. Improved comprehension of the variations in plantar tarsometatarsal ligament anatomy is expected to help diagnose diverse injuries to this region, better understand the structural pathomechanism of the injuries, and contribute to successful treatment. Clin. Anat. 32:699-705, 2019. © 2019 Wiley Periodicals, Inc.

Morphologic variations of the dorsal tarsometatarsal ligaments of the foot.

This study investigated the anatomical features of the dorsal tarsometatarsal ligaments of the foot for the purpose of analyzing the ligamentous components and classifying their types. Fifty embalmed cadaveric feet from 27 adult cadavers were dissected in this study. The dorsal tarsometatarsal ligaments comprised nine components (first cuneiform-first metatarsal, dCn1-M1; first cuneiform-second metatarsal, dCn1-M2; second cuneiform-second metatarsal, dCn2-M2; third cuneiform-second metatarsal, dCn3-M2; third cuneiform-third metatarsal, dCn3-M3; third cuneiform-fourth metatarsal, dCn3-M4; cuboid-third metatarsal, dCb-M3; cuboid-fourth metatarsal, dCb-M4; cuboid-fifth metatarsal, dCb-M5). The dCn3-M4 and dCb-M3 had not been previously reported. The dCn1-M1, dCn1-M2, dCn3-M2, dCn3-M4, and dCb-M3 had only one band, the dCn2-M2 had two bands, and the others had one or two bands. The ligaments originating from Cb attached simultaneously to M3 and M4 (4/50), M4 and M5 (7/50), or M3 and M5 (5/50), which were Y-shaped (dCb-M3, 4 and dCb-M3, 5), or V-shaped (dCb-M4, 5). The dorsal tarsometatarsal ligaments were classified into four types according to the presence of each component. In Type I (52%), Type II (36%), Type III (10%), and Type IV (2%), all components were observed except for one, two, three, and four components, respectively. The dimensions of each component were measured, and as a result the dCn1-M1 was found to be the widest and longest of the dorsal ligaments while the dCn1-M2 was found to be the thickest. The dorsal tarsometatarsal ligaments comprised nine components and were classified into four types. Clin. Anat. 32:212-217, 2019. © 2018 Wiley Periodicals, Inc.

Use of dynamic images in radiology education: Movies of CT and MRI in the anatomy classroom.

Radiology education is a key component in many preclinical anatomy courses. However, the reported effectiveness of radiology education within such anatomy classrooms has varied. This study was conducted to determine if a novel educational method using dynamic images of movies of computed tomography (CT) and magnetic resonance imaging (MRI) was effective in radiology education during a preclinical anatomy course, aided by clay modeling, specific hand gestures (digit anatomy), and reports from dissection findings uploaded to the anatomy course website (digital reports). Feedback surveys using a five-point Likert scale were administered to better clarify students' opinions regarding their understanding of CT and MRI of anatomical structures, as well as to determine if such preclinical radiology education was helpful in their clinical studies. After completion of the anatomy course taught with dynamic images of CT and MRI, most students demonstrated an adequate understanding of basic CT and MR images. Additionally, students in later clinical years generally believed that their study of radiologic images during the preclinical anatomy course was helpful for their clinical studies and clerkship rotations. Moreover, student scores on imaging anatomy examinations demonstrated meaningful improvements in performance after using dynamic images from movies of CT and MRI.

Substrate roughness induces the development of defective E-cadherin junctions in human gingival keratinocytes.

PURPOSE: The entry of bacteria or harmful substances through the epithelial seal of human gingival keratinocytes (HGKs) in the junctional epithelium (JE) is blocked by specialized intercellular junctions such as E-cadherin junctions (ECJs). However, the influence of roughened substrates, which may occur due to apical migration of the JE, root planing, or peri-implantitis, on the development of the ECJs of HGKs remains largely unknown. METHODS: HGKs were cultured on substrates with varying levels of roughness, which were prepared by rubbing hydrophobic polystyrene dishes with silicon carbide papers. The activity of c-Jun N-terminal kinase (JNK) was inhibited with SP600125 or by transfection with JNK short hairpin RNA. The development of intercellular junctions was analyzed using scanning electron microscopy or confocal laser scanning microscopy after immunohistochemical staining of the cells for E-cadherin. The expression level of phospho-JNK was assessed by immunoblotting. RESULTS: HGKs developed tight intercellular junctions devoid of wide intercellular gaps on smooth substrates and on rough substrates with low-nanometer dimensions (average roughness [Ra]=121.3±13.4 nm), although the ECJs of HGKs on rough substrates with low-nanometer dimensions developed later than those of HGKs on smooth substrates. In contrast, HGKs developed short intercellular junctions with wide intercellular gaps on rough substrates with mid- or high-nanometer dimensions (Ra=505.3±115.3 nm, 867.0±168.6 nm). Notably, the stability of the ECJs was low on the rough substrates, as demonstrated by the rapid destruction of the cell junction following calcium depletion. Inhibition of JNK activity promoted ECJ development in HGKs. JNK was closely associated with cortical actin in the regulation of ECJs in HGKs. CONCLUSIONS: These results indicate that on rough substrates with nanometer dimensions, the ECJs of HGKs develop slowly or defectively, and that this effect can be reversed by inhibiting JNK.

Digital report in an anatomy laboratory: a new method for team-based dissection, reporting, and evaluation.

PURPOSE: Digital report (DR), a new method for students' dissection report, has been introduced to replace the traditional method in the anatomy laboratory. METHODS: Laboratory tasks were assigned to groups of five students, and each group was asked to make a DR of their dissection tasks and upload it on the website for the anatomy course developed by the authors' institution. For creating the DR, students were instructed to take photographs of their findings with digital cameras, to mark the orientation and label the structures on the photograph. Students were assessed as a group by evaluating the DR. All the photographs of the DR were saved to construct a database that can be used by the students who will take the anatomy course in the following years. A questionnaire consisting of 14 questions was administered at the end of the anatomy course to evaluate the effectiveness of the DR. RESULTS: The results of the student survey showed that the DR was useful for making the students participate more actively in the teamwork for dissection, and for making dissection reports by referring to the DR made by the students from previous years. The DR was also more helpful for the anatomy teacher to assess student learning in the anatomy laboratory than conventional practical examinations and paper-based dissection reports. CONCLUSIONS: DR, a paperless report of team-based dissection, is concurrent with the 'digital' age and is in line with the need for a more systematic and objective evaluation of students' dissection.

Classification system for flexor digitorum accessorius longus muscle variants within the leg: clinical correlations.

The flexor digitorum accessorius longus (FDAL), a variant leg muscle, can cause tarsal tunnel syndrome. This study was performed to classify the variants of the FDAL by dissection and to correlate the dissection results with clinical cases of tarsal tunnel syndrome caused by this muscle. Eighty lower limbs of embalmed Korean cadavers were dissected. MR images of two clinical cases of tarsal tunnel syndrome caused by the FDAL were correlated with the dissection results. The FDAL was observed in nine out of 80 specimens (11.3%) and it was classified into three types depending on its site of origin and its relationship to the posterior tibial neurovascular bundle (PTNV) in the leg. In Type I (6.3%), the FDAL originated in the leg and ran superficially along the PTNV, either not crossing (Type Ia, 3.8%) or crossing (Type Ib, 2.5%) the neurovascular bundle. In Type II (6.3%), it originated in the tarsal tunnel. Most FDALs followed a similar course in the tarsal tunnel and the plantar pedis. On correlating the MR images of the clinical cases with this classification, the FDAL corresponded to Types Ia and II. All three types of FDAL can compress the tibial nerve in the tarsal tunnel or the distal leg. Clarification of the topographical relationship between this muscle and the PTNV would help to improve the results of surgery for tarsal tunnel syndrome caused by the FDAL.

Effects of microstructure and deformation conditions on the hot formability of Ni-Ti-Hf shape memory alloys.

Ingots of Ni-Ti-Hf shape memory alloys were prepared by vacuum arc re-melting. Isothermal hot compression tests were conducted at temperatures ranging from 700 to 1000 degrees C and at strain rates from 10(-2) s(-1) to 1.0 s(-1). A decrease in the Ni content below 50.2 at.% significantly deteriorated the hot workability due to the formation of a brittle second phase. Also, the low Ni content alloy showed poor workability when the temperature exceeded 900 degrees C. Additional compression tests were conducted under various conditions to clarify the effects of the chemical composition, solidification anisotropy, and the strain rate.

Morphological study of the inferior transverse scapular ligament.

The suprascapular nerve can be compressed by the inferior transverse scapular ligament (ITSL), also known as the spinoglenoid ligament, and this entrapment results in dysfunction of the external rotation of the upper arm owing to isolated weakness of the infraspinatus muscle. The morphology of the ITSL has not been adequately characterized. The aim of this study was to clarify the morphological characteristics of the ITSL. In total, 110 shoulders from 72 cadavers were dissected in this study. The ITSL was present in 73 (66.4%) of the 110 specimens, and comprised membrane in 40 (36.4%), ligament in 25 (22.7%), and both membrane and ligament in eight (7.3%). This structure could be classified into three types on the basis of its shape: band-like (33.6%, type I), triangular (15.5%, type II), or irregular (17.3%, type III). In the spinoglenoid notch, the suprascapular nerve was always close to the lateral margin of the scapular spine. The length of the ligament between its origin and insertion sites ranged from 8.7 to 23.4 mm at its superior margin and from 8.9 to 17.5 mm at its inferior margin. The ligament width and thickness at its midportion ranged from 1.6 to 10.0 mm and from 0.1 to 1.2 mm, respectively. The results of this study improve understanding of the ITSL and will be helpful for successful diagnoses and treatments for selective suprascapular nerve entrapment.

Posterior tibiotalar ligament: an anatomic study correlated with MRI.

This study was performed to clarify the morphologic characteristics of two layers of the posterior tibiotalar ligament (PTT) and two bands of the deep PTT (dPTT), and to correlate the dissection findings with MR images. Sixty-four ankles from 42 cadavers were examined. The origin and insertion sites of the superficial PTT (sPTT) and the two bands of the dPTT were identified, and their length, width, and thickness were measured. MRI was performed on four ankles before serial sectioning or dissection. The serial sections were taken at a thickness of 2 mm. The sPTT was observed in 50 out of 60 dissected specimens (83.3%), taken from 64 ankles of 42 cadavers. The dPTT was observed in all specimens. The sPTT, superficial band of the dPTT (sdPTT), and deep band of the dPTT (ddPTT) arose from the inferior surface of the medial malleolus. The sPTT attached to the posterior process of the talus, and the sdPTT and ddPTT attached to the depression below the articular facet for the medial malleolus. The sPTT and two bands of the dPTT could be distinguished on coronal MR images, where the sPTT appeared as a thin string superficial to the two bands of the dPTT, which were separated as two thick, low-density strings. In the coronal plane of frozen sections, the outermost sPTT appeared as a thin, white bundle attached to the sdPTT. The PTT is composed of superficial and deep layers, and the dPTT is composed of superficial and deep bands.

Variable composition of the internal and external branches of the accessory nerve.

The purpose of this study was to clarify the composition of the internal and external branches (IB and EB) of the accessory nerve. Fifty-seven half heads of 34 adult cadavers were used. The IB and EB of the accessory nerve were mixed with the cranial root (CR), vagus nerve, and spinal root (SR). The IB was classified into five types and the EB into four types according to their composition. The IB consisted of only CR in 7.0% of the 57 cases, and of the CR and the vagus nerve in 52.6%; the IB did not exist in 12.3%. The EB was only composed of the SR in 19.3% of cases, the SR and CR in 52.6%, and the SR, CR, and the vagus nerve in 21.1%. There were 14 combinations of IB and EB types. The most common combination was the IB with the CR and the vagus nerve, and the EB with the SR and CR (31.6%). The combination of IB and EB comprising CR and SR, respectively, was not observed. The IB and EB are known to consist of the CR and SR of the accessory nerve, respectively. However, this study shows that there are no IB and EB comprising only the CR and SR, respectively, and the branches have various combinations of the CR, SR, and vagus nerve.