Characterization of the pterygomeningeal artery based on branching pattern and muscular distribution.

PURPOSE: The pterygomeningeal (accessory meningeal) artery arises from the middle meningeal or maxillary artery. Although there is the potential that this artery may be wounded by the surgery for the temporomandibular joint disorder, the current state of anatomical knowledge is insufficient. This study investigated the appearance and the branching pattern of this artery as a means to its characterization. METHODS: The pterygomeningeal artery was dissected in 14 cadavers and its branches and their distributions to the muscles inside the mandible were examined. RESULTS: The maxillary artery passed lateral to the lateral pterygoid muscle. The pterygomeningeal artery arose from the middle meningeal or maxillary artery. It ascended anteriorly and coursed medial or lateral to the mandibular nerve. It passed above the pterygospinous ligament and then descended. The ascending trunk gave some lateral branches to the lateral pterygoid muscle. The branches sometimes passed lateral to the mandibular nerve even if the pterygomeningeal artery coursed medial. The descending trunk was divided into middle and medial branches, which supplied the medial pterygoid muscle and the tensor veli palatini, respectively. The pterygomeningeal artery was sometimes equally bifurcate near the origin, and the counterparts passed lateral and medial to the mandibular nerve. The distributions of the medial and lateral counterparts were equivalent to those of the descending trunk and the lateral branches, respectively. CONCLUSION: The pterygomeningeal artery contains three groups of muscular branches, which sometimes appear in a bifurcate form. Their positions relative to the mandibular nerve and the pterygospinous ligament characterize the artery; this information may help to avoid iatrogenic injury.

The branching pattern of the middle temporal artery and the relation with the temporal fascia.

PURPOSE: Although the middle temporal artery is used for maxillofacial and otological flap surgeries, the anatomical knowledge of the artery is insufficient to corroborate its usage. This study has investigated the interrelationship between the artery and the temporal fascia to enhance its availability. METHODS: The middle temporal artery was dissected in ten cadavers, and its spatial relations with the temporal fascia and muscle and the adjacent structures were examined. RESULTS: The middle temporal artery arose behind the mandibular head or neck and in front of the external acoustic meatus. It penetrated the temporal fascia external to the junction between the zygomatic process and the supramastoid crest. The artery gave off a thin branch in the space between the superficial and the deep layers of the fascia and is divided into two branches piercing the deep layer to supply the temporalis. The anterior branch anastomosed with the deep temporal artery; furthermore, it gave off the slender ramus coursing on the base of the zygomatic process to communicate with the masseteric artery. The posterior branch passed along the supramastoid crest, gave off a slender ramus and ascended in the groove of the temporal bone. CONCLUSION: The branching pattern of the middle temporal artery and its positions relative to the temporal fascia and the landmark structures are helpful in identifying the artery, designing favourable flaps and avoiding unfavourable bleeding during surgery. They are also beneficial in developing the clinical usage of the artery.

Morphological Features of the Branching Pattern of the Hypoglossal Nerve.

The hypoglossal or twelfth cranial nerve is the motor nerve to the extrinsic and intrinsic muscles of the tongue, and the superior root of the ansa cervicalis and the thyrohyoid and geniohyoid branches are delivered through the nerve. This study investigated the muscular branches of the hypoglossal nerve to clarify their spatial relationships with the muscles of the tongue and the neighboring structures. The muscles and the nerve were gross anatomically examined in 42 cadavers. The superior root and the thyrohyoid branch left the nerve near the occipital and lingual arteries, respectively. The extrinsic muscles consisted of some components, and the geniohyoid branch and the lingual branches arose on the hyoglossus. The ascending lingual branches formed a plexus on the anterior part of the hyoglossus and were divided into the proximal and distal groups. They supplied the two parts of the hyoglossus, the three bundles of the styloglossus and the superior and inferior longitudinal muscles and communicated with the lingual nerve. The descending lingual branches supplied the inferior part of the genioglossus, and the terminal branches gave intramuscular twigs to its main part and the transverse and vertical muscles. The findings indicated that the branching pattern of the hypoglossal nerve is characterized by the positional relationships to the components of the extrinsic muscles. The hyoid bone can be an effective marker to identify the branches and affected position if it was used in combination with the morphology of the extrinsic muscles, and the knowledge of their variations is also beneficial. Anat Rec, 302:558-567, 2019. © 2018 Wiley Periodicals, Inc.

Morphological Features of the Glossopharyngeal Nerve in the Peripharyngeal Space, the Oropharynx, and the Tongue.

The glossopharyngeal nerve comprises sensory, motor and parasympathetic fibers, and its problem results in several disorders. This study investigated the glossopharyngeal nerve to elucidate the characteristics of its extracranial course and branching pattern. The nerve and adjacent structures were gross anatomically examined in 32 cadavers. The glossopharyngeal nerve descended from the jugular foramen in the peripharyngeal space. It dodged between the carotid arteries and the internal jugular vein and distributed the carotid and pharyngeal branches that formed the plexus with the branches of the vagus and sympathetic nerves. The glossopharyngeal nerve curved anteriorly around the stylopharyngeus and supplied it and the glossopharyngeus. However, it occasionally disappeared because it penetrated the stylopharyngeus. The nerve passed medially to the stylohyoid ligament to enter the oropharynx, with its entry located medially to the facial artery. It appeared anteriorly to the stylopharyngeus and the palatopharyngeus and inferiorly to the palatine tonsil in the oropharynx. Its appearance was obscured beneath the tonsil and, sometimes, beneath the longitudinal muscles. The nerve distributed the branches to the palatine tonsil, which formed a plexus with those that pierced the glossopharyngeus from the outside. At the root of the tongue, the nerve ramified into the posterior branches to the epiglottic vallecula, the medial ones the lingual tonsil and the vallate papillae and the anterior ones the vallate and foliate papillae. This study suggests that, occasionally, the detection of the glossopharyngeal nerve is challenging, and its association with the pharyngeal muscles and the facial artery can facilitate its localization. Anat Rec, 302:630-638, 2019. © 2018 Wiley Periodicals, Inc.

Structural arrangement of the intrinsic muscles of the tongue and their relationships with the extrinsic muscles.

The tongue is a dense muscular organ, in which the muscles are arranged in a confusing pattern. The intrinsic muscles were gross anatomically investigated in 25 cadavers to clarify their configuration. The superior longitudinal muscle (SLm) ran beneath the dorsal mucosa and was divided into bundles by the other muscles passing through it to the dorsum. The external bundle of the styloglossus, with the palatoglossus, coursed externally to the hyoglossus. Their fibers spread beneath the SLm or attached to the apex and the inferior longitudinal muscle (ILm) ascended from the root and joined them. The genioglossus and the anterior part of the hyoglossus extended internally and externally to the ILm, respectively, to the dorsum, and the vertical muscle was sandwiched between them. The transverse muscle passed laterally from the lingual septum. The fibers of the posterior part of the hyoglossus converged to the root and spread beneath the SLm. The intersections between these vertical and transverse fibers divided one another into bundles or lamellae. The middle bundle of the styloglossus, passing between the two parts of the hyoglossus, was divided into slips by the intersection with the genioglossus. The internal bundle of the styloglossus, with the glossopharyngeus, descended internally to the posterior part to the root. The findings indicate that the intrinsic and extrinsic muscles of the tongue are not independent groups, and their fibers form a three-dimensional latticework. Each muscle contains numerous bundles or lamellae as functional units that can act separately or cooperate across the muscles.

Morphometric analysis of temporomandibular joint elements.

PURPOSE: To study the morphology of temporomandibular joint (TMJ) elements and examine the feasibility of a novel biofidelic articular disc casting technique. METHODS: 18 formalin-fixed cadavers (77.8% female, 22.2% male) with mean (SD) death age of 71.9 (13.7) years were used for this study. In each specimen the masseter muscle, mandibular ramus, and articular disc were dissected bilaterally and measured for length, width, and thickness. All anatomic measurements were made using a digital slide caliper (Hawk Inc., Cleveland, OH). Further, a novel method for the creation of biofidelic articular disc models was established through trial and error. Models were measured for accuracy against their biological counterparts. RESULTS: Left articular disc length and thickness were inversely correlated (r = -0.58, p < 0.049). Direct correlations existed between right disc and ramus thickness (r = 0.56, p < 0.039), masseter length and thickness (r = 0.59, p < 0.009), and masseter width and thickness (r = 0.66, p < 0.003). Comparison of the model measurements with their biological counterparts found no significant differences. DISCUSSION: These observed correlations between elements of the TMJ hold relevance for oral-maxillofacial surgeons and researchers examining disorders of the TMJ. Additionally, our casting technique proved accurate in modeling human articular discs.

Configuration of the extrinsic muscles of the tongue and their spatial interrelationships.

PURPOSE: The tongue is a highly muscular organ, and the extrinsic muscles of the tongue overlap one another, which makes their configuration intricate. The aim was to clarify their spatial interrelationships. METHODS: The extrinsic muscles of the tongue were gross anatomically investigated in 42 cadavers. RESULTS: The hyoglossus consisted of two parts arising from the hyoid body and the greater horn, respectively. They ascended to the tongue external to the genioglossus. The quadrilateral anterior part contained several parallel bundles, and the triangular posterior part comprised of three bundles converging to the insertion. The genioglossus consisted of many compartments. Although its fibers radiated from the mental spine to the tongue internal to the inferior longitudinal muscle, the lateral fibers of the inferior parts passed externally to it, and the most inferior part attached to the hyoid bone and the epiglottis. The chondroglossus arising from the lesser horn ascended internally to the lateral fibers of the inferior parts. The styloglossus arising from the styloid process coursed externally and internally to the hyoglossus and between its two parts. The external and internal bundles fused with the fibers of the palatoglossus and the superior pharyngeal constrictor, respectively. Three bundles were inserted into the apex with the inferior longitudinal muscle or joined the inferior parts of the genioglossus. CONCLUSIONS: The extrinsic muscles are subdivided into small groups of fibers depending on their spatial interrelationships, suggesting that they contain many functional units. Some units act separately, and others cooperate across the traditional boundaries of the muscles.

Spatial relationship between the palatopharyngeus and the superior constrictor of the pharynx.

PURPOSE: The palatopharyngeus and the superior constrictor act during swallowing. However, because they overlap one another, their morphologies have been controversial. This study examined these muscles to clarify their configuration and interrelationships. METHODS: The attachments and the fiber arrangement of the superior constrictor and the palatopharyngeus were gross anatomically examined in 28 Japanese cadavers. RESULTS: The most superior fibers of the superior constrictor arose from the palate and interfused with the lateral fibers of the palatopharyngeus. Consequently, their origins and insertions were arranged in a continuous line, respectively, and these flat muscles formed a sheet. The palatopharyngeus rotated 90 degrees, from the origin to the insertion, about its long axis, and its superior and inferior surfaces turned into internal and external, respectively. Its lateral fibers passed on the internal surface of the superior constrictor, and these two muscles were inserted into the pharyngeal raphe with an overlap, indicating that the muscular sheet was folded back. Its medial fibers consisted of two layers at the origin and were interdigitated with the insertion of the levator veli palatini. The superior layer was joined by the salpingopharyngeus and dispersed into the pharyngeal wall. The inferior one was joined by the stylopharyngeus and descended along the palatopharyngeal arch to be inserted into the thyroid cartilage and the epiglottis. CONCLUSIONS: These two muscles formed a sheet that was partially folded back. It is suggested that the superior constrictor and the lateral fibers cooperate as sphincters, and the medial fibers and the stylopharyngeus as elevators.

Distribution of matrix proteins in perichondrium and periosteum during the incorporation of Meckel's cartilage into ossifying mandible in midterm human fetuses: an immunohistochemical study.

Immunohistochemical localization of versican and tenascin-C were performed; the periosteum of ossifying mandible and the perichondrium of Meckel's cartilage, of vertebral cartilage, and of mandibular condylar cartilage were examined in midterm human fetuses. Versican immunoreactivity was restricted and evident only in perichondrium of Meckel's cartilage and vertebral cartilage; conversely, tenascin-C immunoreactivity was only evident in periosteum. Therefore, versican and tenascin-C can be used as molecular markers for human fetal perichondrium and fetal periosteum, respectively. Meckel's cartilage underwent endochondral ossification when it was incorporated into the ossifying mandible at the deciduous lateral incisor region. Versican immunoreactivity in the perichondrium gradually became weak toward the anterior primary bone marrow. Tenascin-C immunoreactivity in the primary bone marrow was also weak, but tenascin-C positive areas did not overlap with versican-positive areas; therefore, degradation of the perichondrium probably progressed slowly. Meanwhile, versican-positive perichondrium and tenascin-C-positive periosteum around the bone collar in vertebral cartilage were clearly discriminated. Therefore, the degradation of Meckel's cartilage perichondrium during endochondral ossification occurred at a different rate than did degradation of vertebral cartilage perichondrium. Additionally, the perichondrium of mandibular condylar cartilage showed tenascin-C immunoreactivity, but not versican immunoreactivity. That perichondrium of mandibular condylar cartilage has immunoreactivity characteristic of other periosteum tissues may indicate that this cartilage is actually distinct from primary cartilage and representative of secondary cartilage.

Gross anatomical observations of attachments of the middle pharyngeal constrictor.

The pharyngeal muscles overlap each other and some of their parts have different areas of origin. Such arrangements make the interrelationships among pharyngeal muscles complicated. This study investigated the attachments of the middle constrictor to clarify its configuration and re-examine its functions. The gross anatomies of the pharyngeal and neighboring muscles were examined in 41 cadavers. The middle constrictor arose from the stylohyoid ligament and the hyoid bone, and its fibers were divided into three overlapping groups. The anterosuperior group ascended posterosuperiorly from the ligament and the lesser horn and fanned out. The middle group ascended posterosuperiorly from the greater horn and fanned out. The posteroinferior group fanned out from the posterior part of the greater horn, while the middle constrictor arose internally to the hyoglossus; some fibers often passed externally, and their fibers sometimes intersected around the lingual artery, which ran between them. Some fibers attached to the hyoglossus, occasionally to the stylohyoid and the posterior belly of the digastric, but seldom to the lingual artery and the triticeal cartilage in the thyrohyoid ligament. The three groups were inserted into the pharyngeal raphe, and the descending fibers joined the longitudinal pharyngeal muscles. The ascending and descending fibers rarely reached the top of the pharynx and the thyroid cartilage, respectively. The fiber arrangement suggested that, besides constriction of the pharynx, the ascending and descending fibers of the middle constrictor can act as an elevator muscle, and the irregular attachments could affect the functions of the muscles and vessels.

Interrelationships between the innervations from the laryngeal nerves and the pharyngeal plexus to the inferior pharyngeal constrictor.

PURPOSE: The inferior constrictor is innervated by the pharyngeal plexus and the external and recurrent laryngeal nerves. The communication between these nerves may influence the innervations. However, the relations of their anastomoses with the innervations have been unclear. This gross anatomical study re-examined the configuration of the inferior constrictor and investigated the variations of the anastomoses and the innervations of the constrictor to clarify their interrelationships. METHODS: The inferior constrictor and the branches of the superior and recurrent laryngeal nerves and the pharyngeal plexus were examined under a binocular microscope in 30 Japanese cadavers. RESULTS: The inferior constrictor consisted of the oblique fibers from the thyroid and cricoid cartilages and the horizontal ones from the cricoid. The oblique fibers were innervated by the pharyngeal plexus from the dorsal and ventral surfaces. The external laryngeal nerve gave twigs to the oblique fibers and the cricothyroid from the lateral surface. The recurrent laryngeal nerve supplied the horizontal fibers from the ventral surface. The internal laryngeal nerve sometimes and the main trunk of the superior laryngeal nerve rarely supplied the upper oblique fibers. The communicating branches between the laryngeal nerves and the pharyngeal plexus sometimes gave twigs to the constrictor from the dorsal surface. CONCLUSIONS: The innervations to the inferior constrictor from the laryngeal nerves and the pharyngeal plexus are classified into some types based on their branching patterns and anastomoses, suggesting that the dysfunctions of the laryngopharyngeal region vary according to the positional relationships between the affected part and the innervations types.

Spatial relationships between the morphologies and innervations of the scalene and anterior vertebral muscles.

The prevertebral muscles are innervated by the cervical ventral rami. However, little information is available on the spatial relationships between the muscles and the supplying branches. This gross anatomical study investigated the prevertebral muscles and the nerves in 26 cadavers to elucidate their spatial interrelationships and the nerve pathways to each muscle. These muscles were characterized by the variations in the vertebral attachments. The scalenus medius was divisible into the dorsal and ventral parts. The scaleni anterior and medius attached to both the anterior and posterior tubercles of the cervical transverse processes. The oblique fibers arising from the transverse processes joined the vertical part of the longus colli. The rectus capitis anterior, the longus capitis and the scalene anterior and minimus were innervated by the ventromedial branches of the cervical ventral rami, and the branches passed between the origins of the proximal muscles to supply the longus colli. The rectus capitis lateralis and the scalenus medius were innervated by their dorsolateral branches, and the branches pierced the medius to the scalenus posterior. The roots of the brachial plexus passed between the scalenus anterior and the ventral part of the medius. The penetrations by the upper roots and the interconnecting fibers passing between the roots were found in the muscle bundles arising from the fourth or fifth cervical vertebrae. Their anomalies are the possible causes of the cervical-brachial disorders, and the knowledge of the innervation and the variations in this study seems to be useful for surgical and non-surgical treatments.

Classification of pharyngeal muscles based on innervations from glossopharyngeal and vagus nerves in human.

PURPOSE: The pharyngeal muscles are innervated by the glossopharyngeal and vagus nerves. However, their spatial interrelationships with the innervating branches have been unclear. This study examined the pharynx to elucidate their precise relationships for the anatomical evidence of the functional diagnosis. METHOD: The muscles and nerves were dissected under a binocular microscope in 44 sides of 22 cadavers fixed with 8% formalin. RESULTS: The pharyngeal muscles overlapped each other, and the pharyngeal constrictors sometimes linked to adjacent muscles. The uppermost part of the superior constrictor arose from the soft palate, and sometimes contained the fibers attaching to the petrous part of the temporal bone. Anomalous bundles were frequently found between the superior and middle constrictors and the stylopharyngeus. The stylopharyngeus and the glossopharyngeal part of the superior constrictor were innervated by the glossopharyngeal nerve, which occasionally penetrated the stylopharyngeus. The pharyngeal plexus not only spread onto dorsolateral surface of the pharynx but also sent branches between the constrictors. The plexus supplied the superior constrictor and salpingo- and palatopharyngei from their dorsal surface and the middle and inferior constrictors from their ventral and dorsal surfaces. The inferior constrictor received additional innervations from the laryngeal nerves. CONCLUSIONS: The innervations pattern suggests that the pharyngeal muscles comprise four groups: the first innervated by the glossopharyngeal nerve, the second and third by the pharyngeal plexus, and the fourth by the plexus and the laryngeal nerves. The stylopharyngeus descends between the second and third groups, and its penetration may cause the anomalous bundles between them.

[Relationships between application for the School of Oral Health Care Sciences and awareness as a dental hygienist].

The aim of this study was to investigate students' awareness of applying for the School of Oral Health Care Sciences, Tokyo Medical and Dental University and being dental hygienists in the future. Forty-seven students (24 first-year students and 23 second-year students) in the school answered the questionnaire including questions about becoming dental hygienists and certified social workers. We requested them to answer by recalling their thoughts at the time of application. The chi-square test and Fisher's exact test were used for statistical analysis. A significantly larger number of the first-year students thought that a dental hygienist was an attractive occupation compared with the second-year students. The time when first-year students decided to apply for the school was classified into three categories: by August, from September to December of the year preceding admission, and January or February of the admission year. The ratios of the students who decided to apply for the school were 42%, 21%, 38% respectively. The results of analyzing first-year students' questionnaire responses were as follows. A significantly larger number of students who wished or decided to apply for the school by August of the year preceding admission also applied for other dental hygiene programs. The number of students who thought that a dental hygienist was an attractive occupation was significantly greater among the students who wished or decided to apply for the school by August of the year preceding admission than among those who didn't. We consider that these students were highly motivated to become dental hygienists. It is important for the school to recruit students with high motivation.

Development of a liquid culture system for megakaryocyte terminal differentiation: fibrinogen promotes megakaryocytopoiesis but not thrombopoiesis.

Megakaryocyte differentiation is composed of three distinct stages: formation of erythromegakaryocytic progenitor cells, maturation of megakaryocytes and production of platelets. We have developed a liquid culture system for megakaryocyte terminal differentiation from haematopoietic stem cells into proplatelets. In this system, CD34+ cells isolated from human cord blood, differentiated to CD41+ cells, were classified either as propidium iodide (PI)+ cells (large) or PI- cells (small) by fluorescence-activated cell sorting analysis on the late-stage CD41+ cells. Transmission electron microscopy showed that the cultured small cells were morphologically identical to platelets isolated from normal peripheral blood. Moreover, the number of differentiated cells that were CD42b-positive attained an approximately 60-fold expansion over that of the primary CD34+ cells in this culture system. Furthermore, gene expression of megakaryocytopoietic transcriptional factors, GATA-1 and NF-E2, and several megakaryocytic markers such as glycoprotein (GP)IIb and thromboxane synthase was observed in the individual differentiation stage. Treatment with fibrinogen, a ligand of GPIIb/IIIa, increased the number of CD41+/PI+ cells, but treatment in the late stage suppressed CD41+/PI- cell formation, suggesting that fibrinogen promotes megakaryocytopoiesis, but not thrombopoiesis. We conclude that this liquid culture system using human CD34+ cells may be used to mimic the physiological development from haematopoietic stem cells into megakaryocytes, as well as promote subsequent thrombopoiesis.

Possible role of dentin matrix in region-specific deposition of cellular and acellular extrinsic fibre cementum.

The mechanism whereby a region-specific deposition of the two types of cementum (cellular cementum and acellular extrinsic fibre cementum) is regulated on the growing root surface was tested using bisphosphonate-affected teeth of young rats and guinea pigs. The animals were injected subcutaneously with 8 or 10 mg P x kg body weight(-1) x day(-1) of 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) for 1 or 2 weeks. In rat molars, HEBP prevented mineralization of newly formed root dentin matrix and totally inhibited de novo deposition of acellular extrinsic fibre cementum. Instead, thick cellular cementum was induced on the non-mineralized root dentin surface, irrespective of the position of the root. In both animals, cellular cementum was also induced on the non-mineralized surface of root analogue dentin in HEBP-affected incisors, where only acellular extrinsic fibre cementum is deposited under normal conditions. In normal rat molars, dentin sialoprotein (DSP) was concentrated along the dentin-cellular cementum border, but not that of dentin and acellular extrinsic fibre cementum. In HEBP-affected rat incisors, DSP was shown to penetrate through the non-mineralized dentin into the surrounding tissues, but not through the mineralized portions. These data suggest that, at the site of cellular cementum formation, putative inducing factors for cellular cementum might diffuse into the periodontal space through the newly deposited mantle dentin matrix before it is mineralized. At earlier stages of root formation, mantle dentin might mineralize more promptly not to allow such diffusion. The timing of mineralization of mantle dentin matrix might be the key determinant of the types of the cementum deposited on the growing root surface.

Morphological influence of ascorbic acid deficiency on endochondral ossification in osteogenic disorder Shionogi rat.

The influences of chronic deficiency of L-ascorbic acid (AsA) on the differentiation of osteo-chondrogenic cells and the process of endochondral ossification were examined in the mandibular condyle and the tibial epiphysis and metaphysis by using Osteogenic Disorder Shionogi (ODS) rats that bear an inborn deficiency of L-gulonolactone oxidase. Weanling male rats were kept on an AsA-free diet for up to 4 weeks, until the symptoms of scurvy became evident. The tibiae and condylar processes of scorbutic rats displayed undersized and distorted profiles with thin cortical and scanty cancellous bones. In these scorbutic bones, the osteoblasts showed characteristic expanded round profiles of rough endoplasmic reticulum, and lay on the bone surface where the osteoid layer was missing. Trabeculae formation was deadlocked, although calcification of the cartilage matrix proceeded in both types of bone. Scorbutic condylar cartilage showed severe disorganization of cell zones, such as unusual thickening of the calcification zone, whereas the tibial cartilage showed no particular alterations (except for a moderately decreased population of chondrocytes). In condylar cartilage, hypertrophic chondrocytes were encased in a thickened calcification zone, and groups of nonhypertrophic chondrocytes occasionally formed cell nests surrounded by a metachromatic matrix in the hypertrophic cell zone. These results indicate that during endochondral ossification, chronic AsA deficiency depresses osteoblast function and disturbs the differentiation pathway of chondrocytes. The influence of scurvy on mandibular condyle cartilage is different from that on articular and epiphyseal cartilage of the tibia, suggesting that AsA plays different roles in endochondral ossification in the mandibular condyle and long bones.