Relationship between first tarsometatarsal ligament morphology and its continuity with the fibularis longus and first tarsometatarsal joint degeneration.

This study explored the relationship between the morphological characteristics of the first tarsometatarsal ligaments and fibularis longus (FL) and the severity of articular cartilage degeneration in the first tarsometatarsal joint. Sixty legs from 30 cadavers were examined. The plantar, dorsal, and medial first tarsometatarsal ligaments were classified by fiber bundle number, and their morphological characteristics (fiber bundle length, width, thickness) were measured. The FL was categorized by its continuity with the plantar first tarsometatarsal ligament (PTML): Type A, connection with the PTML only on the first metatarsal; Type B, connection along the entire PTML; and Type C, no connection with the PTML. The severity of articular cartilage degeneration was assessed in four stages. No significant differences in cartilage degeneration among ligament types were found. Negative correlations were observed between the fiber bundle width and thickness of the PTML and the severity of cartilage degeneration. FL was classified as Type A in 68%, Type B in 27%, and Type C in 5% of feet. The fiber bundle thickness of the PTML in Type B was greater than in other types. Our findings suggest that smaller fiber bundle width and thickness in the PTML may be associated with severe cartilage degeneration. The FL had continuity with the PTML in 95% of feet and could enhance the mechanical strength of the PTML in Type B feet.

An atypical inferior gluteal artery passing through the piriformis muscle.

PURPOSE: In this article, we report a case of an atypical inferior gluteal artery that passed through the piriformis muscle when it emerged from the pelvic cavity in an elderly Japanese female cadaver. We speculate that this atypical artery could be entrapped and compressed by the piriformis muscle and may therefore be associated with piriformis syndrome; however, the anatomical characteristics of such an atypical artery have not been previously reported. To assess this potential association, the atypical inferior gluteal artery was anatomically examined. METHODS: The cadaver examined in this report was a 97-year-old Japanese female who was donated to The Nippon Dental University for use in medical education and research. The atypical inferior gluteal artery and surrounding structures in half of the pelvis were examined macroscopically. RESULTS: The atypical inferior gluteal artery arose from the common arterial trunk, formed by itself and the superior gluteal artery, passed through the superior proximal part of the piriformis muscle, and left the pelvic cavity. It supplies branches to the lower half of the gluteus maximus and proximal part of the long head of the biceps femoris muscle. The piriformis muscle originates from the 2nd to 4th sacral vertebrae and attaches to the greater trochanter via a single short tendon. CONCLUSION: According to our findings, when the atypical inferior gluteal artery is entrapped and compressed, ischemic signs and symptoms may emerge in the lower buttocks and proximal posterior thigh. These results provide a new perspective for the diagnosis and treatment of piriformis syndrome.

Anatomical study of type classification and surface area of attachment sites for tibialis anterior tendon.

BACKGROUND: The purpose of this study was to clarify the attachment types of the tibialis anterior tendon (TAT) in Japanese fixed cadavers and to determine the attachment site area in three dimensions. METHODS: We examined 100 feet from 50 Japanese cadavers. The TAT was classified according to differences in the number of fiber bundles as: Type I, with one fiber bundle; Type II, with two fiber bundles; and Type III, with three fiber bundles. The attachment site area of the TAT was measured using a three-dimensional scanner. RESULTS: Cases were Type II in 95% and Type III in 5%, with no cases of Type I identified. In Type II, mean attachment site areas were 85.2 ± 18.2 mm2 for the medial cuneiform bone (MCB) and 72.4 ± 19.0 mm2 for the first metatarsal bone (1 MB), showing a significantly larger area for MCB than for 1 MB. CONCLUSIONS: These findings suggest the possibility of ethnic differences in TAT attachment types and suggest that TAT attachments in Japanese individuals are highly likely to be Type II, with rare cases of Type III. Accurate measurement of attachment site areas is possible with appropriate three-dimensional measurements.

The sublingual branch of the lingual nerve: Anatomical study and suggestion for a new terminology.

The lingual nerve carries somatosensory fibers from the anterior two-thirds of tongue. The parasympathetic preganglionic fibers arising from the chorda tympani also travel with the lingual nerve in the infratemporal fossa to synapse in the submandibular ganglion to innervate the sublingual gland. However, only a few studies have investigated the specific nerve that innervates the sublingual gland and surrounding tissue i.e., the so-called sublingual nerve. Therefore, this study aimed to clarify the anatomy and definition of the sublingual nerves. Thirty sides from formalin fixed cadaveric hemiheads underwent microsurgical dissection of the sublingual nerves. The sublingual nerves were found on all sides and categorized into three branches, i.e., branches to the sublingual gland, branches to the mucosa of the floor of the mouth, and gingival branches. Additionally, branches to the sublingual gland were subcategorized into types I and II based on the origin of the sublingual nerve. We suggest that the lingual nerve branches should be categorized into five branches, i.e., branches to the isthmus of the fauces, sublingual nerves, lingual branches, posterior branch to the submandibular ganglion, and branches to the sublingual ganglion.

The relationship of tooth crown dimensions between first molar and central incisor in maxilla.

The purpose of this study was to investigate a correlation between the cusp dimensions of the first molar and mesiodistal crown diameters of the central incisors in the maxilla. The study materials were composed of dental casts from 29 modern Japanese female subjects with a mean age of 20 years and 8 months. The mesiodistal crown diameters of the maxillary central incisors were measured. The mesiodistal and bucco-lingual crown diameters and the cusp diameters of the maxillary first molars, such as the paracone, metacone, protocone, and hypocone, were also measured. The crown areas and indices of the first molars were calculated. The Spearman's single rank correlation coefficients between the mean values for the crown dimensions of the first molars and the mesiodistal crown diameters of the central incisors were calculated. The hypocone cusp diameter and the hypocone index were the largest compared to those of the paracone, protocone, and metacone cusps. The bucco-lingual diameter and hypocone cusp diameter of the first molars positively correlated with the mesiodistal crown diameters of the central incisors on the same sides. There were positive correlations between the hypocone index of the first molars and the mesiodistal crown diameters of the central incisors. Based on the results, if a large hypocone is observed in eruption of the maxillary first molars, it will be predictable that of the mesiodistal crown diameter of the maxillary central incisor large.

Relationship between index of orthodontic treatment need dental health component (IOTN-DHC) and caries prevalence in school-age children.

OBJECTIVES: The objectives of the study were to investigate the relationship between caries prevalence and the Index of Orthodontic Treatment Need Dental Health Component (IOTN-DHC) in school-age children who live in the dentistless area and to consider the effective way to reduce the potential progression of malocclusion with the growth through the dental survey in Arbulag district, Khövsgöl province, Mongolia. MATERIALS AND METHODS: The 95 school-age children (49 males, 46 females) who participated in the study were born in and were residents of Arbulag district, Khövsgöl province, Mongolia. The mean ages of the participants were 8.3 years (y) ± 1.7 y for males and 8.8 y ± 1.7 y for females. The Mann-Whitney U test was performed to determine the sex difference for the dmf/DMF index. The relationship between the IOTON-DHC and the dmf/DMF index was statistically examined using Spearman's rank correlation coefficient. RESULTS: Regarding the dmf/DMF index, no sex difference was observed. There were significant, fair positive correlations between the IOTON-DHC grade and F; between the IOTON-DHC grade and DMF index in males. There were significant, fair positive correlations between the IOTON-DHC grade and M; between the IOTON-DHC grade and DMF index in females. CONCLUSIONS: Significant, fair positive correlations were found between the caries prevalence and the grade of malocclusion. Thus, prevention and early treatment of dental caries in a mixed dentition may be effective to reduce the potential progression of malocclusions in dentistless area.

Clinical Anatomy Research Association in Oral and Maxillofacial Surgery.

ABSTRACT: Sufficient knowledge of anatomy is critical for oral and maxillofacial surgeons to provide the best treatment to their patients. The authors have recently established the "Clinical Anatomy Research Association in Oral and Maxillofacial Surgery." There is no doubt as to the benefits of collaboration between oral and maxillofacial surgeons/radiologists and anatomists. In this article, we share what was accomplished at the first annual online conference and discuss our mission for the future.

Morphological features of the lateral plantar ligament of the transverse metatarsal arch.

The aim of this study was to elucidate the morphological characteristics of the lateral Lisfranc ligament in a large sample. This investigation examined 100 legs from 50 cadavers. Each of the lower limbs was dissected to identify the plantar aspect of the transverse metatarsal arch, and morphological characteristics of the lateral plantar ligament were assessed, including the length, width, and thickness of the fiber bundles. The majority of plantar ligaments originated from the base of M5 and the plantar aspect of the lateral cuneiform (LC). The lateral plantar ligament could be classified into three types: Type I, a band-like fiber bundle originating from the base of M5 to the LC (41%); Type II, originating from the base of M5 and the plantar aspect of LC and mostly connected the blending the fiber bundles of the tibialis posterior (TP) and long plantar ligament (LPL) (21%); and Type III, with no ligaments originating from the base of M5 and plantar aspect of the LC (38%). The morphological characteristics of Type I lateral plantar ligament were as follows: length, 31.8 ± 3.7 mm; width, 2.3 ± 1.0 mm; and thickness, 0.2 ± 0.3 mm. The morphology of the lateral plantar ligament showed variation, originating from the base of M5 and the plantar aspect of LC most commonly, but this was not the case in 38% of limbs. The findings suggest that the lateral plantar ligament might play a role in the transverse tarsal arch, indicating a cooperative mechanism with the TP and LPL.

Relationship between morphology of transverse bundle of ulnar collateral ligament and adjacent tissues.

PURPOSE: The purpose of this study was to clarify the incidence of the transverse bundle (TB) of the ulnar collateral ligament (UCL), the relationships between TB morphology and morphology of the anterior bundle (AB) or posterior bundle (PB) of the UCL, and the relationship between the TB and the posterior common tendon (PCT). METHODS: This study examined 38 elbows from 23 cadavers. TB, AB, and PB were classified morphologically. The TB was classified as: type I, TB does not continue the entire length of the AB; or type II, TB continues the entire length of the AB. The AB and PB were classified as: type I, could be separated as single bundles; or type II, could not be separated. We also observed specimens by focusing on the continuity between the TB and PCT. Fisher's exact test was used to examine the relationship between TB type and AB or PB type. RESULTS: A TB was identified in all 38 elbows (100%), and continued to the AB in all specimens. No significant relationship was evident between TB type and AB or PB type. Continuity of TB fibers and the PCT was seen in 26 elbows (72%). CONCLUSION: This study suggested that the morphology of the transverse bundle may be unrelated to the morphology of the anterior bundle or posterior bundle.

The origin structure of each finger in the flexor digitorum superficialis muscle.

PURPOSE: The flexor digitorum superficialis muscle (FDS) is considered the most important of the forearm flexors for maintaining elbow valgus stability. However, the relationships between the origin structure of each finger of the FDS and the anterior oblique ligament (AOL) of the ulnar collateral ligament and the common tendon (CT) in the proximal part, and morphological features are unclear. The purpose of this study was to clarify the relationships between the origin structure of each finger of the FDS and the AOL and the CT, as well as to clarify the morphological features of the muscle belly of each finger of the FDS. METHODS: This study examined 20 elbows. The origin of each finger was examined. Muscle mass, muscle fiber bundle length, and the pennation angle of each finger were also measured. RESULTS: In all cases, the third and fourth digits originated from the radius, the anterior common tendon (ACT), and the posterior common tendon (PCT). The second and fifth digits (18 elbows) or an independent fifth digit (2 elbows) originated from the ACT, the PCT, the AOL, and other soft tissues of the elbow. Muscle mass and muscle fiber bundle length in the muscle belly of the third and fourth digits were significantly heavier and longer, respectively, than in the muscle belly of the second and fifth digits. CONCLUSION: Because the second and fifth digits or an independent fifth digit originated from the AOL, their contraction may cause tension in the AOL.

Anatomical variations in the insertion of the peroneus longus tendon.

BACKGROUND: This study aimed to inspect anatomical variations in the insertion of the peroneus longus tendon (PLT) using a large sample of cadavers. METHODS: In total, 104 legs from 52 Japanese cadavers were used. The PLT was identified behind the lateral malleolus and carefully followed up to its insertion in the foot. All insertion slips of the PLT were located and documented. RESULTS: Mainly, the PLT was inserted to the base of the first metatarsal (1MT) in all 104 ft. Attachment to the medial cuneiform was present in 20.2%, and the first dorsal interossei was present in 36.5%. The anterior frenular ligament was observed in 31.7%, and attachment to the flexor digiti minimi brevis and opponens digiti minimi was present in 31.7%. The posterior frenular ligament was observed in 5.8%. An additional band was observed in 3.9%, and the adductor hallucis consisting of a caput obliquum was present in 3.9%. No statistically significant differences in the PLT were observed between genders or laterality (right vs. left). CONCLUSIONS: These findings suggest that the main function of the PLT is resisting the varus force on the 1MT; however, as the PLT has various attachment sites, it may also be involved in the stabilizing action of the longitudinal and transverse arches. Therefore, these variations and functions appear to be associated with a difficult diagnosis at the first clinical evaluation.

Relationships between differences in the number of fiber bundles of the anterior talofibular ligament and differences in the angle of the calcaneofibular ligament and their effects on ankle-braking function.

PURPOSE: The aim was to clarify the relationships between differences in the number of fiber bundles of the anterior talofibular ligament (ATFL) and differences in the angle of the calcaneofibular ligament (CFL) with respect to the long axis of the fibula and their effects on ankle braking function. METHODS: The study sample included 110 Japanese cadavers. ATFLs were categorized as: Type I with one fiber bundle; Type II with two fiber bundles with incomplete separation and complete separation; and Type III with three fiber bundles. The CFLs were categorized according to the angles of the CFLs with respect to the long axis of the fibula and the number of fiber bundles. Six categories were established: CFL10° (angle of the CFL with respect to the long axis of the fibula from 10° to 19°); CFL20° (range 20°-29°); CFL30° (range 30°-39°); CFL40° (range 40°-49°); CFL50° (range 50°-59°); and CFL2 (CFLs with two crossing fiber bundles). RESULTS: ATFL was Type I in 34 legs (31%), Type II in 66 legs (60%), and Type III in 10 legs (9%). Five CFL categories were identified: CFL10° in 4 feet (3.7%); CFL20° in 23 feet (20.9%); CFL30° in 34 feet (30.9%); CFL40° in 33 feet (30%); CFL50° in 15 feet (13.6%); and CFL2 in one foot (0.9%). Type III contained mainly CFL40° and CFL50° (7 of 10 feet). CONCLUSIONS: ATFL and CFL appear to cooperate in the ankle joint braking function.

The relationships between the quadratus plantae and the flexor digitorum longus and the flexor hallucis longus.

PURPOSE: The purpose of this research was to clarify the relationships between quadratus plantae (QP) and flexor digitorum longus (FDL) and flexor hallucis longus (FHL) using large-scale specimens. METHODS: This study examined 116 legs from 62 Japanese cadavers. The QP was classified as: Type I, formed by the lateral and medial heads; Type II, the lateral head is absent; and Type III, the medial head is absent. The FHL branches to the lesser toes were classified as: Type A, connection from FHL to toe 2; Type B, connection from FHL to toes 2 and 3; Type C, connection from FHL to toes 2-4. Next, the relationships between QP and FHL and FDL were observed. RESULTS: Type I accounted for 87%, Type II for 10%, and Type III for 3%. Type A accounted for 33%, Type B for 53%, and Type C for 14%. Regarding the relationship between QP and FDL, regardless of the classification of the connections of the FHL tendon slip to the lesser toes, QP attachments to FDL branching to toes 2, 3, and 4 were seen in 47-59%. Furthermore, QP attachments to FDL branching to toes 2, 3, 4, and 5 were seen in 41-47%. CONCLUSIONS: QP appears to function strongly to counter the oblique pull of FDL and FHL and as a lesser digit plantar flexor.

Differences in the strain applied to Achilles tendon fibers when the subtalar joint is overpronated: a simulation study.

PURPOSE: The purpose of this study was to investigate the strain applied to each of the tendon fiber bundles of the medial head of the gastrocnemius (MG), the lateral head of the gastrocnemius (LG), and the soleus muscle (Sol) that compose the Achilles tendon (AT) when the subtalar joint is pronated and supinated. METHODS: Three AT twist types (least, moderate, extreme) were investigated. Using the MicroScribe system, the AT and the talocrural and subtalar joints were digitized to reconstruct three-dimensional models. Using this system, subtalar joint rotations in the pronation (20°) and supination (20°) directions were simulated, and the degrees of strain (%) on each tendon were calculated. RESULTS: For all twist types, when the subtalar joint was pronated, MG, LG, and Sol stretched, and when supinated, MG, LG, and Sol shortened. In particular, the least and severe twist types had large degrees of strain of Sol when the subtalar joint was pronated, and furthermore, each tendon fiber composing Sol had different degrees of strain. CONCLUSIONS: The study results suggest that the degree of strain applied within the AT with subtalar joint pronation is not constant, and that, especially in least and extreme twist types, the risk of developing AT disorders may increase.

The effect of differences in the number of fiber bundles of the anterior tibial ligament on ankle braking function: a simulation study.

PURPOSE: The aim was to clarify the effect of differences in the number of fiber bundles of the anterior tibial ligament (ATFL) on ankle braking function. METHODS: The study sample included 81Japanese cadavers. ATFLs were categorized as: Type I with one fiber bundle; Type II with two fiber bundles that were completely separated; and Type III with three fiber bundles. Three-dimensional reconstructions of a single specimen from each category were then created. These were used to simulate and calculate ATFL strain during dorsiflexion (20°) and plantarflexion (30°) on the talocrural joint axis and inversion (20°) on the subtalar joint axis. RESULTS: Almost all types of superior fiber lines were stretched with dorsiflexion and plantarflexion. Regardless of Type, the inferior fiber line was shortened with plantarflexion and stretched with dorsiflexion. The inferior fiber bundle of Type III was shortened only at plantarflexion 30° and inversion 20°, but in all others it was stretched. CONCLUSIONS: The results suggest that Type III was weaker than Type I and Type II in terms of ankle plantarflexion and inversion braking function.

Morphological characteristics of the lateral talocalcaneal ligament: a large-scale anatomical study.

PURPOSE: The purpose of this study is to clarify the morphological characteristics of the lateral talocalcaneal ligament (LTCL). METHODS: This study examined 100 legs from 54 Japanese cadavers. The LTCL was classified into three types: Type I, the LTCL branches from the calcaneofibular ligament (CFL); Type II, the LTCL is independent of the CFL and runs parallel to the calcaneus; and Type III, the LTCL is absent. The morphological features measured were fiber bundle length, fiber bundle width, and fiber bundle thickness. RESULTS: The LTCL was classified as Type I in 18 feet (18%), Type II in 24 feet (24%), and Type III in 58 feet (58%). All LTCLs were associated with the anterior talofibular ligament at the talus. There was no significant difference in morphological characteristics by Type for each ligament. CONCLUSIONS: The LTCL was similar to the CFL in terms of fiber bundle width and fiber bundle thickness.

Comparative Morphology of the Lingual Papillae and Their Connective Tissue Cores in the Tongue of Pallas's Squirrel (Callosciurus erythraeus thai, Kloss, 1917).

We observed the morphology of the papilla linguae (filiform, fungiform, foliate, and vallate) and underlying connective tissue cores (CTCs) in Pallas's squirrel (Callosciurus erythraeus thai) using light and scanning electron microscopy. The tongue was caudally elongated and lacked the lingual torus. Filiform papillae were densely distributed along the dorsal surface of the apex, and the rostral and caudal parts of the corpus, but were attenuated in the lingual root. Two or three vallate papillae that were rounded or elongated were situated at the boundary between the caudal part of the corpus and lingual root, and foliate papillae and associated cone-like processes were observable in the lateral margin of the caudal end. The epithelial surface of filiform papillae had a main process and a few associated processes that varied between short and elongated, depending on the location. Filiform papillae CTCs appeared to have a few processes that caudally surrounded a concavity and were morphologically variable based on location. Moreover, fungiform papillae CTCs appeared to be columnar cores and had a shallow convex curve at the top. The Pallas's squirrel's tongue exhibited transitional morphological characteristics between Rodentia and other mammalian species, in that they lacked the lingual torus and had CTCs of lingual papillae that were somewhat morphologically similar to those of other non-Glires species, especially treeshrews and tamarins, rather than those of other Rodentia species.

Structure of the Achilles tendon at the insertion on the calcaneal tuberosity.

Findings on the twisting structure and insertional location of the AT on the calcaneal tuberosity are inconsistent. Therefore, to obtain a better understanding of the mechanisms underlying insertional Achilles tendinopathy, clarification of the anatomy of the twisting structure and location of the AT insertion onto the calcaneal tuberosity is important. The purpose of this study was to reveal the twisted structure of the AT and the location of its insertion onto the calcaneal tuberosity using Japanese cadavers. The study was conducted using 132 legs from 74 cadavers (mean age at death, 78.3 ± 11.1 years; 87 sides from men, 45 from women). Only soleus (Sol) attached to the deep layer of the calcaneal tuberosity was classified as least twist (Type I), both the lateral head of the gastrocnemius (LG) and Sol attached to the deep layer of the calcaneal tuberosity were classified as moderate twist (Type II), and only LG attached to the deep layer of the calcaneal tuberosity was classified as extreme twist (Type III). The Achilles tendon insertion onto the calcaneal tuberosity was classified as a superior, middle or inferior facet. Twist structure was Type I (least) in 31 legs (24%), Type II (moderate) in 87 legs (67%), and Type III (extreme) in 12 legs (9%). A comparison between males and females revealed that among men, 20 legs (24%) were Type I, 57 legs (67%) Type II, and eight legs (9%) Type III. Among women, 11 legs (24%) were Type I, 30 legs (67%) Type II, and four legs (9%) Type III. No significant differences were apparent between sexes. The fascicles of the Achilles tendon attach mainly in the middle facet. Anterior fibers of the Achilles tendon, where insertional Achilles tendinopathy is most likely, are Sol in Type I, LG and Sol in Type II, and LG only in Type III. This suggests the possibility that a different strain is produced in the anterior fibers of the Achilles tendon (calcaneal side) where insertional Achilles tendinopathy is most likely to occur in each type. We look forward to elucidating the mechanisms generating insertional Achilles tendinopathy in future biomedical studies based on the present results.

Gross anatomical study on the human myocardial bridges with special reference to the spatial relationship among coronary arteries, cardiac veins, and autonomic nerves.

Coronary arteries are frequently covered by cardiac muscles. This arrangement is termed a myocardial bridge. Previous studies have shown that myocardial bridges can cause myocardial ischemic diseases or cardiac arrhythmia, but the relevant pathogenic mechanisms remain unknown. We examined 60 hearts from Japanese cadavers macroscopically to clarify the spatial relationships among coronary arteries, cardiac veins and autonomic nerves. We found 86 myocardial bridges in 47 hearts from the 60 cadavers examined (78.3%). Next, we dissected out nine hearts with myocardial bridges in detail under the operating microscope. We found no additional branches of coronary arteries on the myocardial bridge surfaces. However, the cardiac veins, which usually accompany the coronary arteries, ran independently on the myocardial bridge surfaces in the same region. Cardiac autonomic nerves comprised two rami: one was associated with the coronary artery under the myocardial bridge and the other ran on the surface of the bridge. Such spatial relationships among the coronary arteries, cardiac veins and cardiac autonomic nerves at the myocardial bridges are quite similar to those in mouse embryo hearts.