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.

Relationship between Joint and Ligament Structures of the Subtalar Joint and Degeneration of the Subtalar Articular Facet.

This study aimed to clarify the relationship between the joint and ligament structures of the subtalar joint and degeneration of the subtalar articular facet. We examined 50 feet from 25 Japanese cadavers. The number of articular facets, joint congruence, and intersecting angles were measured for the joint structure of the subtalar joint, and the footprint areas of the ligament attachments of the cervical ligament, interosseous talocalcaneal ligament (ITCL), and anterior capsular ligament were measured for the ligament structure. Additionally, subtalar joint facets were classified into Degeneration (+) and (-) groups according to degeneration of the talus and calcaneus. No significant relationship was identified between the joint structure of the subtalar joint and degeneration of the subtalar articular facet. In contrast, footprint area of the ITCL was significantly higher in the Degeneration (+) group than in the Degeneration (-) group for the subtalar joint facet. These results suggest that the joint structure of the subtalar joint may not affect degeneration of the subtalar articular facet. Degeneration of the subtalar articular facet may be related to the size of the ITCL.

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.

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

The medial brachial cutaneous nerve (MBC) originates from the medial cord of the brachial plexus and innervates the skin sensory in the medial posterior surface of the upper arm. Considering previous reports of the primate brachial plexus, the MBC appeared to be the sole branch in the brachial plexus that only some primates possess. However, the detailed descriptions and records regarding the morphology of the MBC and related nerves, their origins and distributions (dermatomes) in particular, were frequently lacked in the previous reports, and it remains unclear why the difference in the MBC appearance exists among primates. In this study, the brachial plexus and its branches were first re-evaluated and certainly identified in several primates, humans, chimpanzee, macaque monkey, lutung, tamarin, squirrel monkey, and spider monkey. The MBC was identified in humans, chimpanzee, spider monkey, and squirrel monkey. In the other species, the intercostobrachial nerve (ICB) originating from some of 1st to 3rd intercostal nerves developed and distributed instead of the MBC. According to the kinesiological and behavioral studies, the former species possessing MBC show high shoulder joint mobility associated with their locomotive patterns. We speculate that the MBC corresponds to transformed ICB; specifically, where it originates presumably transfers from the 1st and/or 2nd intercostal nerves to the brachial plexus, which allows it to reach the upper arm by coursing the shortest distance even if the forelimb is raised high. Therefore, MBC may embody phylogenetic morphogenesis of the nerve associated with the locomotive evolution and adaptation in primate forelimb.

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.

The red ruffed lemur, Varecia rubra (É. Geoffroy Saint-Hilaire, 1812): a comparative morphology investigation of lingual papillae and connective tissue cores.

The morphology of the lingual papillae (filiform, foliate, fungiform, and vallate papillae) and the underlying connective tissue core of the red ruffed lemur (Varecia rubra) of a strepsirrhines species were studied using light and scanning electron microscopy. The filiform papillae distributed at the root of the tongue were larger than the structures distributed at the body and apex. Six to eight vallate papillae were arranged in a Y-shape at the border between the lingual body and the lingual root. Foliate papillae were observed at the posterior lateral border of the tongue. Scanning electron microscopy revealed a primary process and numerous auxiliary processes in the epithelial layer of filiform papillae. After epithelial removal, the connective tissue core of the filiform papilla showed several protrusions surrounding an oval-shaped depression that extended slightly posteriorly, and a large, maple-shaped filiform papilla was seen in the posterior portion of the tongue. The connective tissue cores of the fungiform papillae exhibited a longitudinally ridged cylindrical structure. The connective tissue core of the foliate papillae had numerous tubular projections arranged along a groove with a salivary gland conduit at the base. As a Lemuridae species, the appearance of the fungiform and filiform papillae of the red ruffed lemur is similar to that reported in previous studies of the ring-tailed lemur, with some differences, especially in the filiform papillary connective tissue core at the base and tongue body border. These findings suggest the taxonomic and phylogenetic origins of the lemurs as well as the influence of dietary diversity.

Anatomical Study of Sites and Surface Area of the Attachment Region of Tibial Posterior Tendon Attachment.

BACKGROUND: The purpose of this study was not only to examine the attachment site but also to quantify the effect of the tibialis posterior tendon (TPT) on each attachment site by examining the surface area of the attachment region. METHODS: We examined 100 feet from 50 Japanese cadavers. The TPT attachment to the navicular bone (NB), medial cuneiform bone (MCB), and lateral cuneiform bone (LCB) were set as the main attachment sites (Type I). The attachment seen in Type I with the addition of one additional site of attachment was defined as Type II. Furthermore, surface area was measured using a three-dimensional scanner. RESULTS: Attachment to the NB, MCB, and LCB was present in all specimens. The TPT attachment to the NB, MCB, and LCB comprised 75.1% of total attachment surface area. The ratio of the NB, MCB, and LCB in each type was about 90% in Types II and III, and 70-80% in Types IV-VII. CONCLUSION: The quantitative results demonstrated the NB, MCB, and LCB to be the main sites of TPT attachment, although individual differences in attachment sites exist, further developing the findings of previous studies.

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 characteristics of the infrapatellar fat pad.

The relationship between the morphological characteristics of the infrapatellar fat pad (IFP) and joint deformity has yet to be fully elucidated. Therefore, the purpose of this study was to clarify the morphological characteristics of the IFP and to identify the relationships between morphological characteristics of the IFP and degenerative grade of the articular surface of the patella. This investigation examined 41 legs from 25 Japanese cadavers. The IFP length, width, and volume were measured. It was categorized into three types: Type I, IFP proximal located on medial and lateral sides of the patella; Type II, the IFP proximal only located medially; and Type III, absence of the IFP proximal. Articular surfaces were graded as macroscopically intact or mildly altered (Grade I), moderately (Grade II), or severely (Grade III). Grade III was significantly more frequent than Grades I or II in Type III. IFP volume was significantly larger in Type I than in Types II or III. A negative correlation was found between the degenerative grade of the articular surface of the patella and IFP volume. It was suggested that a relationship between the degenerative grade of the articular surface of the patella and the IFP volume.

An anatomical study of the blood supply to the mylohyoid muscle: the so-called "mylohyoid branch" of the inferior alveolar artery is an arterial anastomosis.

BACKGROUND: The aim of this study was to clarify the morphology of the mylohyoid branch of the inferior alveolar artery and the main blood supply to the mylohyoid muscle. METHODS: The maxillary artery (MA) and inferior alveolar artery (IAA) within the infratemporal fossa, the facial and submental arteries within the submandibular triangle, and the nerve to the mylohyoid muscle and related artery were dissected in twelve sides from embalmed cadaveric heads. The main blood supply to the extraoral (inferior) surface of the mylohyoid muscle was recorded. RESULTS: The mylohyoid branch of the inferior alveolar artery was an anastomosis of the descending branch of either the inferior alveolar or maxillary artery and the ascending branch of either the submental or facial artery. The anastomosis was classified into four types according to the origins of the arteries. The main blood supply to the extraoral surface of the mylohyoid muscle was the submental artery. CONCLUSIONS: The results of this study indicate that the mylohyoid branch of the IAA in human adults is an anastomosis of branches of the maxillary and facial arteries.

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 Effects of Differences in the Morphologies of the Ulnar Collateral Ligament and Common Tendon of the Flexor-Pronator Muscles on Elbow Valgus Braking Function: A Simulation Study.

The anterior bundle (AB) and posterior bundle (PB) of the ulnar collateral ligament and the anterior common tendon (ACT) and posterior common tendon (PCT) of the flexor-pronator muscles have an independent form and an unclear form. The purpose of this study was to clarify the effect of differences in the morphologies of the AB, PB, ACT, and PCT on the elbow valgus braking function. This investigation examined three elbows. In the classification method, the AB, PB, ACT, and PCT with independent forms constituted Group I; the AB, ACT, and PCT with independent forms and the PB with an unclear form constituted Group II; the AB, PB, ACT, and PCT with unclear forms constituted Group III. The strains were calculated by simulation during elbow flexion at valgus at 0° and 10°. At 0° valgus, Group I and Group II showed similar AB and PCT strain patterns, but Group III was different. At 10° valgus, most ligaments and tendons were taut with increasing valgus angle. The average strain patterns of all ligaments and tendons were similar for the groups. The AB, PB, ACT, and PCT may cooperate with each other to contribute to valgus braking.

Importance of anatomy in dental implant surgery.

BACKGROUND: The knowledge of nerves and vessels in the maxillofacial region, particularly the anatomical structures in the maxilla, mandible, tongue muscles, and salivary glands, is essential for dental surgeons. In addition, the structures in the mandibular canal, palate, and maxillary sinus should be understood well. HIGHLIGHT: The arteries and nerves in the maxillofacial region were observed in this study. Some variations in the origin of the inferior alveolar artery were found. Notably, the variations in the origin of the inferior alveolar artery from that of the external carotid artery and a double origin of the inferior alveolar artery were observed. Thus, the maxillary artery may originate from the external carotid and stapedial arteries. The following points are important. (1)The greater palatine artery is always located deeper than the greater palatine nerve. (2)The posterior superior alveolar artery often runs through the compact bone of the maxilla. Using CT scans, the canal of the artery can be observed. (3)Variations in origins of the inferior alveolar artery have been observed. The origin of the inferior alveolar nerve may differ depending on the course of the maxillary artery. CONCLUSIONS: Dental practitioners should, therefore, have a comprehensive knowledge of the anatomy of the maxillofacial region and its variations. Without this knowledge, they should not operate on patients.

Morphological characteristics of the plantar calcaneocuboid ligaments.

BACKGROUND: The aim of this study was to clarify the differences in morphological features between the long plantar ligament (LPL) and the short plantar ligament (SPL). METHODS: This investigation examined 50 legs from 25 Japanese cadavers. The LPL and SPL of each leg were classified into one of three types based on the shape and number of fiber bundles. Then, fiber bundle length, fiber bundle width, and fiber bundle thickness were measured. RESULTS: The LPL was rectangular in shape (Type I) in 12%, hourglass shape (Type II) in 62%, and triangular in shape (Type III) in 26%. The SPL was a single fiber bundle (Type I-a) in 26%, a surface fiber bundle and a deep fiber bundle (Type I-b) in 60%, and a surface fiber bundle (medial and lateral) and a deep fiber bundle (Type II) in 14%. Regarding the morphological characteristics, there were no significant differences among the types in the LPL, but there were differences between types and between surface and deep fiber bundles in the SPL. CONCLUSIONS: For the LPL, the hourglass shape is the most common type. However, there appeared to be no functional difference due to the difference in the shape of the LPL, since there were no significant differences among the types in the LPL. For the SPL, there were types of single, double and triple fiber bundles; there may be functional differences based on the number of fiber bundles and between superficial and deep fibers.

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

BACKGROUND: Evaluating segmental variations in the lumbar plexus is crucial for neurological diagnosis. In the present study, we examined the relationship between the segmental composition of the lumbar plexus and length of the 12th rib. PROCEDURES: To evaluate segmental variations in the lumbar plexus, the furcal nerve (Nf) which forms the boundary between the lumbar and sacral plexus, was used as an index of plexus arrangement. MAIN FINDINGS: Segmental variations in the Nf were classified into four groups on the basis of whether the Nf originated from the ventral rami of L3 and L4 (Nf L3 + L4 group), L4 (Nf L4 group), L4 and L5 (Nf L4 + L5 group), or L5 (Nf L5 group). The Nf L3 + L4 group was associated with short 12th rib, and groups Nf L4 + L5 and Nf L5 were associated with long 12th rib. These findings suggest that the segmental variations in the lumbar plexus are related to the length of the 12th rib. CONCLUSIONS: Therefore, the segmental variations in the lumbar plexus can be evaluated non-invasively and easily by measuring the length of the 12th rib. This may contribute to the diagnosis and treatment of various lumbar radiculopathies.