Evidence for chronic headaches induced by pathological changes of myodural bridge complex.

Clinical studies have shown that there may be a certain relationship between pathological changes of the myodural bridge complex (MDBC) and chronic headaches of unknown cause. But there is still a lack of experimental evidence to explain the possible mechanism. This study aims to further confirm this relationship between MDBC and chronic headaches and explore its potential occurrence mechanism in rats. Bleomycin (BLM) or phosphate-buffered saline (PBS) was injected into the myodural bridge fibers of rats to establish the hyperplastic model of MDBC. After 4 weeks, the occurrence of headaches in rats was evaluated through behavioral scores. The immunohistochemistry staining method was applied to observe the expression levels of headache-related neurotransmitters in the brain. Masson trichrome staining results showed that the number of collagen fibers of MDBC was increased in the BLM group compared to those of the other two groups. It revealed hyperplastic changes of MDBC. The behavioral scores of the BLM group were significantly higher than those of the PBS group and the blank control group. Meanwhile, expression levels of CGRP and 5-HT in the headache-related nuclei of the brain were increased in the BLM group. The current study further confirms the view that there is a relationship between pathological changes of MDBC and chronic headaches of unknown cause. This study may provide anatomical and physiological explanations for the pathogenesis of some chronic headaches of unknown cause.

Identification and characterization of circadian clock genes in the head transcriptome of Conopomorpha sinensis Bradley.

Conopomorpha sinensis Bradley is the most detrimental pest to litchi and longan in China. Adult eclosion, locomotion, mating and oviposition of C. sinensis usually occur at night, regulated by a circadian rhythm. Nevertheless, our understanding of the linkages between adult circadian rhythms and clock genes remains inadequate. To address this gap, transcriptomic analysis was conducted on female and male heads (including antennae) of C. sinensis using the Illumina HiSeq 6000 platform to identify major circadian clock-related genes. The annotated sequences were analyzed by BLASTx, and candidate clock genes were classified based on conservation, predicted domain architectures, and phylogenetic analysis. The analysis revealed a higher conservation of these genes among the compared moths. Further, the expression profile analysis showed a significant spatiotemporal and circadian rhythmic accumulation of some clock genes during development. The candidate clock genes were predominantly expressed in the head, highlighting their crucial function in circadian rhythm regulation. Moreover, CsinPer, CsinTim1, and CsinCry1 displayed similar dynamic expressions with a peak expression level in the 4th age adults, suggesting their involvement in regulation of courtship and mating behaviors. The CsinPer and CsinTim1 mRNA oscillated strongly with a similar phase, containing a peak expression just before the female mating peak. This work will greatly contribute to understanding the circadian clock system of C. sinensis and provide valuable information for further studies of the molecular mechanisms involved in rhythmicity in fruit-boring pests.

Magnetic resonance imaging-based classification of the myodural bridge complex and its influencing factors.

Cerebrospinal fluid (CSF) circulation is considered the third circulation of the human body. Recently, some scholars have proposed the myodural bridge (MDB) as a novel power source for CSF flow. Moreover, the suboccipital muscles can exert a driving force on the CSF via the MDB. This hypothesis is directly supported by head rotation and nodding movements, which can affect CSF circulation. The MDB has been validated as a normal structure in humans and mammals. In addition, the fusion of MDB fibers of different origins that act in concert with each other forms the MDB complex (MDBC). The MDBC may be associated with several CSF disorder-related neurological disorders in clinical practice. Therefore, the morphology of the MDBC and its influencing factors must be determined. In this study, T2-weighted imaging sagittal images of the cervical region were analyzed retrospectively in 1085 patients, and magnetic resonance imaging (MRI) typing of the MDBC was performed according to the imaging features of the MDBC in the posterior atlanto-occipital interspace (PAOiS) and posterior atlanto-axial interspace (PAAiS). The effects of age and age-related degenerative changes in the cervical spine on MRI staging of the MDBC were also determined. The results revealed four MRI types of the MDBC: type A (no MDBC hyposignal shadow connected to the dura mater in either the PAOiS or PAAiS), type B (MDBC hyposignal shadow connected to the dura mater in the PAOiS only), type C (MDBC hyposignal shadow connected to the dura mater in the PAAiS only), and type D (MDBC hyposignal shadow connected to the dura mater in both the PAOiS and PAAiS). The influencing factors for the MDBC typing were age (group), degree of intervertebral space stenosis, dorsal osteophytosis, and degenerative changes in the cervical spine (P < 0.05). With increasing age (10-year interval), the incidence of type B MDBC markedly decreased, whereas that of type A MDBC increased considerably. With the deepening of the degree of intervertebral space stenosis, the incidence of type C MDBC increased significantly, whereas that of type A MDBC decreased. In the presence of dorsal osteophytosis, the incidence of type C and D MDBCs significantly decreased, whereas that of type A increased. In the presence of protrusion of the intervertebral disc, the incidence of type B, C, and D MDBCs increased markedly, whereas that of type A MDBC decreased considerably, with cervical degenerative changes combined with spinal canal stenosis. Moreover, the incidence of both type C and D MDBCs increased, whereas that of type A MDBC decreased. Based on the MRI signal characteristics of the dural side of the MDBC, four types of the MDBC were identified. MDBC typing varies dynamically according to population distribution, depending on age and cervical degeneration (degree of intervertebral space stenosis, vertebral dorsal osteophytosis formation, simple protrusion of intervertebral disc, and cervical degeneration changes combined with spinal canal stenosis, except for the degree of protrusion of the intervertebral disc and the degree of spinal canal stenosis); however, it is not influenced by sex.

The growth and developmental of the myodural bridge and its associated structures in the human fetus.

Myodural bridge (MDB) is a dense connective tissue between suboccipital muscle and dura mater. However, there are few reports on the development and maturation of the human MDB. This study aims to explore the developmental relationship between suboccipital muscle and MDB. 30 head and neck specimens from human fetuses (F) ranging from the 12th to 41st week (W) were made into histological sections. The F12W sections showed evidence that the dura mater dominated by fibroblasts, attached to the posterior atlanto-axial membrane (PAAM) which completely sealed the atlanto-axial space. In the F13W stage, myofibrils of the suboccipital muscle fibers increased significantly in number. At the F14W stage, a gap was observed at the caudal end of the PAAM. Numerous myodural bridge-like structures were observed blending into the dura mater through the gap. At the F19W stage, muscle cells mature. Starting at the F21W stage, the MDB were observed as fibroblasts that cross the atlanto-axial interspace and attach to the dura mater. Therefore, the traction generated by the suboccipital muscles seems to promote the maturity of MDB. This study will provide new morphological knowledge to support future research on the function of the human MDB and regulating the development mechanism of MDB.

A valuable subarachnoid space named the occipito-atlantal cistern.

The cisterna magna has been defined as the space between the inferior margin of the cerebellar vermis to the level of the foramen magnum, while an enlarged dorsal subarachnoid space at the occipito-cervical junction extending from the foramen magnum to the upper border of the axis (C2) is still ignored. Recently, the myodural bridge complex is proved to drive the cerebral spinal fluid flowing via this region, we therefore introduce the "occipito-atlantal cistern (OAC)" to better describe the subarachnoid space and provide a detailed rationale. The present study utilized several methods, including MRI, gross anatomical dissection, P45 sheet plastination, and three-dimensional visualization. OAC was observed to be an enlarge subarachnoid space, extending from the foramen magnum to the level of the C2. In the median sagittal plane, OAC was a funnel shape and its anteroposterior dimensions were 15.92 ± 4.20 mm at the level of the C0, 4.49 ± 1.25 mm at the level of the posterior arch of the C1, and 2.88 ± 0.77 mm at the level of the arch of the C2, respectively. In the median sagittal plane, the spino-dural angle of the OAC was calculated to be 35.10 ± 6.91°, and the area of OAC was calculated to be 232.28 ± 71.02 mm2. The present study provides OAC is a subarachnoid space independent from the cisterna magna. Because of its distinctive anatomy, as well as theoretical and clinical significance, OAC deserves its own name.

A Clinical and Anatomical Study on the Localization of the Temporal Branch of the Facial Nerve Crossing the Zygomatic Arch / Estudio Clínico y Anatómico sobre la Localización del Ramo Temporal del Nervio Facial que Cruza el Arco Cigomático

SUMMARY: To clarify the path of the temporal branch of facial nerve (TB) crossing the zygomatic arch (ZA). Eighteen fresh adult heads specimens were carefully dissected in the zygomatic region, with the location of TB as well as its number documented. The hierarchical relationship between the temporal branch and the soft tissue in this region was observed on 64 P45 plastinated slices. 1. TB crosses the ZA as type I (21.8 %), type II (50.0 %,), and type III (28.1 %) twigs. 2. At the level of the superior edge of the ZA, the average distance between the anterior trunk of TB and the anterior part of the auricle is 36.36±6.56 mm, for the posterior trunk is 25.59±5.29 mm. At the level of the inferior edge of the ZA, the average distance between the anterior trunk of TB and the anterior part of the auricle is 25.77±6.19 mm, for the posterior trunk is 19.16±4.71 mm. 3. The average length of ZA is 62.06±5.36 mm. TB crosses the inferior edge of the ZA at an average of 14.67±6.45 mm. TB crosses the superior edge of the ZA at an average of 9.08±4.54 mm. 4. At the level of the ZA, TB passes on the surface of the pericranium while below the SMAS. The TB obliquely crosses the middle 1/3 part of the superior margin of the ZA and the junction of the middle 1/3 part and the posterior 1/3 part of the inferior margin of the ZA below the SMAS while beyond the periosteum. It is suggested that this area should be avoided in clinical operation to avoid the injury of TB.

El objetivo de estudio fue esclarecer el trayecto del ramo temporal del nervio facial (RT) que cruza el arco cigomático (AC). Se disecaron la región cigomática de 18 especímenes de cabezas sin fijar de individuos adultas y se documentó la ubicación del RT y su número de ramos. La relación jerárquica entre el ramo temporal y el tejido blando en esta región se observó en 64 cortes plastinados o P45. 1º El RT cruza el AC como tipo I (21,8 %), tipo II (50,0 %) y tipo III (28,1 %). 2º A nivel del margen superior del AC, la distancia promedio entre el tronco anterior de RT y la parte anterior de la aurícula fue de 36,36±6,56 mm, para el tronco posterior fue de 25,59±5,29 mm. A nivel del margen inferior del AC, la distancia promedio entre el tronco anterior del RT y la parte anterior de la aurícula era de 25,77±6,19 mm, para el tronco posterior era de 19,16±4,71 mm. 3º La longitud media de RT fue de 62,06±5,36 mm. EL RT cruzaba el margen inferior del AC a una distancia media de 14,67±6,45 mm. El RT cruzaba el margen superior del AC a una distancia media de 9,08±4,54 mm. 4º Anivel del AC, el RT pasaba por la superficie del pericráneo mientras se encuentra por debajo del SMAS. El RT cruza oblicuamente el tercio medio del margen superior del AC y la unión del tercio medio y el tercio posterior del margen inferior del AC por debajo del SMAS, más allá del periostio. Se sugiere que esta área debe evitarse en la operación clínica para evitar la lesión de la RT.

The relationship between compensatory hyperplasia of the myodural bridge complex and reduced compliance of the various structures within the cranio-cervical junction.

The myodural bridge complex (MDBC) is described as a functional anatomic structure that involves the dense connective tissue fibers, muscles, and ligaments in the suboccipital region. It has recently been proposed that the MDBC can influence cerebrospinal fluid (CSF) circulation. In the present study, bleomycin (BLM), a type of antibiotic that is poisonous to cells, was injected into the posterior atlanto-occipital interspace (PAOiS) of rats to induce fibrous hyperplasia of structures in PAOiS. Sagittal sections of tissues obtained from the posterior-occipital region of the rats were stained utilizing the Masson Trichrome staining method. Semiquantitative analysis evidenced that the collagen volume fraction of collagen fibers of the MDBC, as well as the sum of the area of the spinal dura mater and the posterior atlanto-occipital membrane in the BLM group were significantly increased (p < .05) compared to that of the other groups. This finding illustrates that the MDBC fibers as well as other tissues in the PAOiS of rats in the BLM group developed fibrotic changes which reduced compliance of the spinal dura mater. Indeed, the sectional area of the rectus capitis dorsal minor muscle in the BLM group was measured to be increased. These changes may further restrict CSF flow. The present research provides support for the recent hypothesis proposed by Labuda et al. concerning the pathophysiology observed in symptomatic adult Chiari malformation Type I patients, that there exists a relationship between the altered compliance of the anatomic structures within the craniocervical region and the resultant compensatory hyperplasia of the MDBC.

Bony structures at the attachment areas of the cruciate ligaments in human knee joints and their clinical significance-studied using the P45 plastination technique / Estructuras óseas en las áreas de inserción de los ligamentos cruzados en las articulaciones de la rodilla humana y su importancia clínica, estudiadas mediante la técnica de plastinación P45

SUMMARY: For treating cruciate ligament injuries, especially for characterizing the mechanics of the tunnel in cruciate ligament reconstruction, correctly understanding the bony information of the attachment area of the cruciate ligaments is significant. We studied 31 knee joints of middle-aged Chinese adults using the P45 sheet plastination technique, focusing on the attachment areas of the cruciate ligaments, especially the bony structures. The trabeculae at the attachment area were distributed radially and extended deep into the medial wall of the lateral condyle of the femur. However, in the anterior part of the intercondylar eminence, the trabeculae of the anterior group were parallelly arranged along the tendinous fibers of the anterior cruciate ligament, while the trabeculae of the posterior group were parallelly arranged along the perpendicular direction of the anterior cruciate ligament fibers. Similarly, at the attachment area of the lateral wall of the medial condyle of the posterior cruciate ligament, the trabeculae extended radially toward the deep medial condyle. Deep in the posterior part of the intercondylar eminence, the trabeculae were arranged longitudinally. In the anterior part of the intercondylar eminence, the trabeculae were parallelly arranged along the perpendicular directions of ligament fibers. The distribution patterns of the trabecular at the attachment areas of the cruciate ligaments at the ends of the femur and tibia were different. This difference should be considered when orthopedic surgeons reconstruct anterior cruciate ligaments.

Para el tratamiento de lesiones de los ligamentos cruzados, especialmente para caracterizar la mecánica del túnel en su reconstrucción, es importante comprender correctamente la información ósea del área de inserción de estos ligamentos. Estudiamos 31 articulaciones de rodilla de individuos chinos, adultos, de mediana edad, utilizando la técnica de plastinación de láminas P45, centrándonos en las áreas de unión de los ligamentos cruzados, especialmente en las estructuras óseas. Las trabéculas en el área de inserción se distribuyeron radialmente y se extendieron profundamente en la pared medial del cóndilo lateral del fémur. Sin embargo, en la parte anterior de la eminencia intercondílea, las trabéculas del grupo anterior estaban dispuestas paralelamente a lo largo de las fibras tendinosas del ligamento cruzado anterior, mientras que las trabéculas del grupo posterior estaban dispuestas paralelamente a lo largo de la dirección perpendicular de las fibras del ligamento cruzado anterior. De manera similar, en el área de inserción en la cara lateral del cóndilo medial del ligamento cruzado posterior, las trabéculas se extendían radialmente y profundas hacia el cóndilo medial. Profundamente en la parte posterior de la eminencia intercondílea, las trabéculas estaban dispuestas longitudinalmente. En la parte anterior de la eminencia intercondílea, las trabéculas estaban dispuestas paralelamente a lo largo de las direcciones perpendiculares de las fibras del ligamento. Los patrones de distribución del tejido óseo trabecular en las áreas de unión de los ligamentos cruzados en los extremos del fémur y la tibia eran diferentes. Estas diferencias deben tenerse en consideración cuando los cirujanos ortopédicos reconstruyen los ligamentos cruzados anteriores.

A new concept of the fiber composition of cervical spinal dura mater: an investigation utilizing the P45 sheet plastination technique.

PURPOSE: Few reports have been published regarding the microanatomy of the dura mater located at the craniovertebral junction (CVJ). In clinic, the precise microanatomy of the CVJ dura mater would be taken into account, for reducing surgical complications and ineffective surgical outcomes. The main objective of the present investigation was to further elucidate the fiber composition and sources of the cervical spinal dura mater. METHODS: The formalin-fixed adult head and neck specimens (n = 21) were obtained and P45 plastinated section method was utilized for the present study. The fibers of the upper cervical spinal dura mater (SDM) were examined in the P45 sagittal sections in the CVJ area. All photographic documentation was performed via a Canon EOS 7D Mark camera. RESULTS: The posterior wall of the SDM sac at CVJ was found to be composed of stratified fibers, which are derived from three sources: the cerebral dura mater, the occipital periosteum, and the myodural bridge (MDB). The proper layer of the cerebral dura mater passes over the brim of the foramen magnum and enters the vertebral canal to form the inner layer of the SDM, and the fibers originating from the periosteum of the brim of the foramen magnum form the middle layer. The fibers of the MDB are inserted into the SDM and form its outer layer. It was found that the total number of fibers from each origin varied in humans. CONCLUSION: At the CVJ, the posterior wall of the SDM is a multi-layered structure composed of three different originated fibers. The cerebral dura mater, the periosteum located at the brim of the foramen magnum, and MDB contribute to the formation of the SDM. The present study would be beneficial to the choice of surgical approach at the CVJ and the protection of the SDB.

Congenital atlanto-occipital fusion and its effect on the myodural bridge: a case report utilizing the P45 plastination technique / Fusión atlanto-occipital congénita y su efecto sobre el puente miodural: reporte de un caso utilizando la técnica de plastinación P45

SUMMARY: The atlanto-occipital joint is composed of the superior fossa of the lateral masses of the atlas (C1) and the occipital condyles. Congenital Atlanto-occipital fusion (AOF) involves the osseous union of the base of the occiput (C0) and the atlas (C1). AOF or atlas occipitalization/assimilation represents a craniovertebral junction malformation (CVJM) which can be accompanied by other cranial or spinal malformations. AOF may be asymptomatic or patients may experience symptoms from neural compression as well as limited neck movement. The myodural bridge (MDB) complex is a dense fibrous structure that connects the suboccipital muscular and its related facia to the cervical spinal dura mater, passing through both the posterior atlanto-occipital and atlanto-axial interspaces. It is not known if atlas occipitilization can induce structural changes in the MDB complex and its associated suboccipital musculature. The suboccipital region of a cadaveric head and neck specimen from an 87-year-old Chinese male having a congenital AOF malformation with resultant changes to the MDB complex was observed. After being treated with the P45 plastination method, multiple slices obtained from the cadaveric head and neck specimen were examined with special attention paid to the suboccipital region and the CVJM. Congenital atlanto-occipital fusion malformations are defined as partial or complete fusion of the base of the occiput (C0) with the atlas (C1). In the present case of CVJM, unilateral fusion of the left occipital condyle with the left lateral mass of C1 was observed, as well as posterior central fusion of the posterior margin of the foramen magnum with the posterior arch of C1. Also noted was a unilateral variation of the course of the vertebral artery due to the narrowed posterior atlanto-occipital interspace. Surprisingly, complete agenesis of the rectus capitis posterior minor (RCPmi) and the obliques capitis superior (OCS) muscles was also observed in the plastinated slices. Interestingly, the MDB, which normally originates in part from the RCPmi muscle, was observed to originate from a superior bifurcation within an aspect of the nuchal ligament. Therefore, the observed changes involving the MDB complex appear to be an effective compensation to the suboccipital malformations.

RESUMEN: La articulación atlanto-occipital está compuesta por las caras articulares superiores de las masas laterales del atlas (C1) y los cóndilos occipitales. La fusión atlanto-occipital congénita (FAO) implica la unión ósea de la base del occipucio (C0) y el atlas (C1). La FAO u occipitalización/asimilación del atlas representa una malformación de la unión craneovertebral (MUCV) que puede presentar otras malformaciones craneales o espinales. La FAO puede ser asintomática o los pacientes pueden experimentar síntomas de compresión neural así como movimiento limitado del cuello. El complejo del puente miodural (PMD) es una estructura fibrosa densa que conecta el músculo suboccipital y su fascia relacionada con la duramadre espinal cervical, pasando a través de los espacios intermedios atlanto-occipital posterior y atlanto-axial. No se sabe si la occipitilización del atlas puede inducir cambios estructurales en el complejo PMD y en la musculatura suboccipital. Se observó en la región suboccipital de un espécimen cadavérico, cabeza y cuello de un varón chino de 87 años con una malformación congénita de FAO con los cambios resultantes en el complejo PMD. Se examinaron múltiples cortes obtenidos de la muestra de cabeza y cuello después de ser tratados con el método de plastinación P45, con especial atención a la región suboccipital y la MUCV. Las malformaciones congénitas por fusión atlanto-occipital se definen como la fusión parcial o completa de la base del occipucio (C0) con el atlas (C1). En el presente caso de MUCV se observó la fusión unilateral del cóndilo occipital izquierdo con la masa lateral izquierda de C1, así como fusión posterior central del margen posterior del foramen magnum con el arco posterior de C1. También se observó una variación unilateral del curso de la arteria vertebral por el estrechamiento del espacio interatlanto-occipital posterior. Se observó además agenesia completa de los músculos Rectus capitis posterior minor (RCPmi) y oblicuos capitis superior (OCS) en los cortes plastinados. Curiosamente, se observó que el MDB, que normalmente se origina en parte del músculo RCPmi, se origina en una bifurcación superior dentro de un aspecto del ligamento nucal. Por lo tanto, los cambios observados en el complejo PMD parecen ser una compensación de las malformaciones suboccipitales.

A comparative study of the morphology of suboccipital cavernous sinus using magnetic resonance imaging and cast specimens / Un estudio comparativo de la morfología del seno cavernoso suboccipital utilizando imágenes de resonancia magnética y muestras de yeso

SUMMARY: A comparative study of the morphology of suboccipital cavernous sinus (SCS) using MRI and cast specimens was performed. The present retrospective study analysed the craniocervical magnetic resonance venography (MRV) imaging data of 61 patients. Three-dimensional reconstruction was performed using Mimics 19.0. The SCS left-right diameter(d1), distance from the midline (d2), supero-inferior diameter(d3), anteroposterior diameter (d4), distance from posterior diameter to skin (d5), and diameter of the SCS at different parts (d6-d8) were measured. Comparison between MRV images and cast specimens, the SCS, marginal sinus, anterior condylar vein, and vertebral artery venous plexus were symmetrical and could be bilaterally displayed, whereas the presence of extra condylar vein and posterior condylar vein exhibited different types. The adjacency between the SCS and its communicating vessels and changes in its communicating vessels corresponded well with the MRV images and cast specimens. Many types of the presence of left and right lateral condylar and posterior condylar veins were found in the cast specimens, which could be divided into the bilateral presence of posterior condylar and lateral condylar veins, unilateral presence of posterior condylar veins, and unilateral presence of lateral condylar vein. A total of 61 cases analysed using MRV images revealed the bilateral presence of posterior condylar and lateral condylar veins (77.1 %), the unilateral presence of posterior condylar vein (18.0 %), and the unilateral presence of lateral condylar vein (9.8 %), of which the bilateral presence of posterior condylar and lateral condylar veins accounted for the largest proportion. MRV images and cast specimens of the SCS showed its normal morphological structure and adjacency, thus providing accurate and complete Three-dimensional imaging anatomical data of the SCS and its communicating vascular structures. This study enriches the Chinese SCS imaging anatomy data and may be valuable in clinical practice.

RESUMEN: Se realizó un estudio comparativo de la morfología del seno cavernoso suboccipital (SCS) mediante resonancia magnética y muestras de yeso. El presente estudio retrospectivo analizó los datos de imágenes de venografía por resonancia magnética (RNM) craneocervical de 61 pacientes. La reconstrucción tridimensional se realizó con Mimics 19.0. Se midió: el diámetro izquierdo-derecho del SCS (d1), la distancia desde la línea mediana (d2), el diámetro superoinferior (d3), el diámetro anteroposterior (d4), la distancia desde el diámetro posterior hasta la piel (d5) y el diámetro del SCS en diferentes partes (d6-d8). En la comparación entre las imágenes RNM y las muestras de yeso, el SCS, el seno marginal, la vena condilar anterior y el plexo venoso de la arteria vertebral eran simétricos y se observaron bilateralmente, mientras que la presencia de la vena extracondilar y la vena condilar posterior presentaba tipos diferentes. La proximidad del SCS y sus vasos comunicantes y los cambios en sus vasos comunicantes se correspondieron bien con las imágenes de RNM y los especímenes moldeados. Se encontraron muchos tipos de venas condilares laterales y condilares posteriores izquierda y derecha en las muestras de yeso, que podrían dividirse en presencia bilateral de venas condilares posteriores y condilares laterales, presencia unilateral de venas condilares posteriores y presencia unilateral de venas condilares laterales. Un total de 61 casos analizados mediante imágenes MRV revelaron la presencia bilateral de venas condilares posteriores y condilares laterales (77,1 %), la presencia unilateral de venas condilares posteriores (18,0 %) y la presencia unilateral de venas condilares laterales (9,8 %) de los cuales la presencia bilateral de las venas condilar posterior y condilar lateral representó la mayor proporción. Las imágenes de RNM y las muestras de yeso del SCS mostraron su estructura morfológica y adyacencia normales, lo que proporcionó datos anatómicos de imágenes tridimensionales precisos y completos del SCS y sus estructuras vasculares comunicantes. Este estudio enriquece los datos de anatomía de imágenes de SCS chino y puede ser valioso en la práctica clínica.

Architecture of the cancellous bone in human proximal tibia based on P45 sectional plastinated specimens.

PURPOSE: To reveal differences in the pattern of trabecular architecture in the epiphysis and metaphysis of the proximal tibia. METHODS: The trabecular architecture of the proximal tibia was observed in 27 P45 plastinated knee specimens. RESULTS: In the medial and lateral condyles, under the articular cartilage surrounded by the medial or lateral meniscus, the cancellous bone is formed by thick and dense trabecular bands, which run longitudinally in the epiphysis and then pass through the epiphyseal line to terminate on the slanted cortex of the metaphysis. In the intercondylar eminence, the trabeculae are arranged basically in a network. In the central portion of the tibial metaphysis, cancellous bone consists of fine arcuate trabeculae, which extend to the anterior and posterior cortices, respectively. These trabeculae are intersected sparsely and form trusses over the medullary cavity. Near the areas of attachment of the iliotibial tract, tibial collateral ligament, anterior and posterior cruciate ligaments, and patellar ligament, the cancellous bone is locally reinforced with patchy trabeculae, dense radiating trabeculae, or two orthotropic trabecular bands. CONCLUSION: This study provides further accurate anatomical information on the trabeculae of the proximal tibia. The soft structures of knee joint, including the articular cartilage, menisci, and ligaments, and the slanted cortices of the metaphysis are important landmarks for the location of different arrangements of the cancellous architecture. The present results are beneficial for clinical diagnosis and treatment of pathologies of the knee joint, or the establishment of a finite element analysis model of the knee joint.

Head-nodding: a driving force for the circulation of cerebrospinal fluid.

The myodural bridge (MDB) is a dense connective tissue bridge connecting the suboccipital muscles to the spinal dura mater, and it has been proven to be a normal common existing structure in humans and mammals. Some scholars believe that the suboccipital muscles can serve as a dynamic cerebrospinal fluid (CSF) pump via the MDB, and they found head rotations promote the CSF flow in human body, which provided evidence for this hypothesis. Head movement is a complex motion, but the effects of other forms of head movement on CSF circulation are less known. The present study explored the effects of head-nodding on CSF circulation. The CSF flow of 60 healthy volunteers was analyzed via cine phase-contrast magnetic resonance imaging at the level of the occipitocervical junction before and after one-minute-head-nodding period. Furthermore, the CSF pressures of 100 volunteers were measured via lumbar puncture before and after 5 times head-nodding during their anesthetizing for surgical preparation. As a result, it was found that the maximum and average CSF flow rates at the level of the upper border of atlas during ventricular diastole were significantly decreased from 1.965 ± 0.531 to 1.839 ± 0.460 ml/s and from 0.702 ± 0.253 to 0.606 ± 0.228 ml/s respectively. In the meantime, the changes in the ratio of cranial and caudal orientation of the net flow volume were found differed significantly after the one-minute-head-nodding period (p = 0.017). And on the other hand, the CSF pressures at the L3-L4 level were markedly increased 116.03 ± 26.13 to 124.64 ± 26.18 mmH2O. In conclusion, the head-nodding has obvious effects on CSF circulation and head movement is one of the important drivers of cerebrospinal fluid circulation. We propose that the suboccipital muscles, participating in various head movements, might pull the dura sac via the myodural bridge, and thus, head movement provides power for the CSF circulation.

The morphology, biomechanics, and physiological function of the suboccipital myodural connections.

The myodural bridge (MDB) connects the suboccipital musculature to the spinal dura mater (SDM) as it passed through the posterior atlanto-occipital and the atlanto-axial interspaces. Although the actual function of the MDB is not understood at this time, it has recently been proposed that head movement may assist in powering the movement of cerebrospinal fluid (CSF) via muscular tension transmitted to the SDM via the MDB. But there is little information about it. The present study utilized dogs as the experimental model to explore the MDB's effects on the CSF pressure (CSFP) during stimulated contractions of the suboccipital muscles as well as during manipulated movements of the atlanto-occiptal and atlanto-axial joints. The morphology of MDB was investigated by gross anatomic dissection and by histological observation utilizing both light microscopy and scanning electron microscopy. Additionally biomechanical tensile strength tests were conducted. Functionally, the CSFP was analyzed during passive head movements and electrical stimulation of the suboccipital muscles, respectively. The MDB was observed passing through both the dorsal atlanto-occipital and the atlanto-axial interspaces of the canine and consisted of collagenous fibers. The tensile strength of the collagenous fibers passing through the dorsal atlanto-occipital and atlanto-axial interspaces were 0.16 ± 0.04 MPa and 0.82 ± 0.57 MPa, respectively. Passive head movement, including lateral flexion, rotation, as well as flexion-extension, all significantly increased CSFP. Furthermore, the CSFP was significantly raised from 12.41 ± 4.58 to 13.45 ± 5.16 mmHg when the obliques capitis inferior (OCI) muscles of the examined specimens were electrically stimulated. This stimulatory effect was completely eliminated by severing the myodural bridge attachments to the OCI muscle. Head movements appeared to be an important factor affecting CSF pressure, with the MDB of the suboccipital muscles playing a key role this process. The present study provides direct evidence to support the hypothesis that the MDB may be a previously unappreciated significant power source (pump) for CSF circulation.

Existence and features of the myodural bridge in Gentoo penguins: A morphological study.

Recent studies have evidenced that the anatomical structure now known as the myodural bridge (MDB) connects the suboccipital musculature to the cervical spinal dura mater (SDM). In humans, the MDB passes through both the posterior atlanto-occipital and the posterior atlanto-axial interspaces. The existence of the MDB in various mammals, including flying birds (Rock pigeons and Gallus domesticus) has been previously validated. Gentoo penguins are marine birds, able to make 450 dives per day, reaching depths of up to 660 feet. While foraging, this penguin is able to reach speeds of up to 22 miles per hour. Gentoo penguins are also the world's fastest diving birds. The present study was therefore carried out to investigate the existence and characteristics of the MDB in Gentoo penguin (Pygoscelis papua), a non-flying, marine bird that can dive. For this study, six Gentoo penguin specimens were dissected to observe the existence and composition of their MDB. Histological staining was also performed to analyze the anatomic relationships and characteristic of the MDB in the Gentoo penguin. In this study, it was found that the suboccipital musculature in the Gentoo penguin consists of the rectus capitis dorsalis minor (RCDmi) muscle and rectus capitis dorsalis major (RCDma) muscle. Dense connective tissue fibers were observed connecting these two suboccipital muscles to the spinal dura mater (SDM). This dense connective tissue bridge consists of primarily type I collagen fibers. Thus, this penguin's MDB appears to be analogous to the MDB previously observed in humans. The present study evidences that the MDB not only exists in penguins but it also has unique features that distinguishes it from that of flying birds. Thus, this study advances the understanding of the morphological characteristics of the MDB in flightless, marine birds.

The myodural bridge complex defined as a new functional structure.

PURPOSE: The connective tissue between suboccipital muscles and the cervical spinal dura mater (SDM) is known as the myodural bridge (MDB). However, the adjacent relationship of the different connective tissue fibers that form the MDB remains unclear. This information will be highly useful in exploring the function of the MDB. METHODS: The adjacent relationship of different connective tissue fibers of MDB was demonstrated based upon three-dimensional visualization model, P45 plastinated slices and histological sections of human MDB. RESULTS: We found that the MDB originating from the rectus capitis posterior minor muscle (RCPmi), rectus capitis posterior major muscle (RCPma) and obliquus capitis inferior muscle (OCI) in the suboccipital region coexists. Part of the MDB fibers originate from the ventral aspect of the RCPmi and, together with that from the cranial segment of the RCPma, pass through the posterior atlanto-occipital interspace (PAOiS) and enter into the posterior aspect of the upper cervical SDM. Also, part of the MDB fibers originate from the dorsal aspect of the RCPmi, the ventral aspect of the caudal segment of the RCPma, and the ventral aspect of the medial segment of the OCI, enter the central part of the posterior atlanto-axial interspace (PAAiS) and fuse with the vertebral dura ligament (VDL), which connects with the cervical SDM. CONCLUSIONS: Our findings prove that the MDB exists as a complex structure which we termed the 'myodural bridge complex' (MDBC). In the process of head movement, tensile forces could be transferred possibly and effectively by means of the MDBC. The concept of MDBC will be beneficial in the overall exploration of the function of the MDB.

Existence of myodural bridge in the trachemys scripta elegans: indication of its important physiological function / Existencia del puente miodural en trachemys scripta elegans: indicación de su importante función fisiológica

The myodural bridge (MDB) is confirmed that connecting the most of suboccipital muscles to the cervical dura mater through the posterior intervertebral spaces and widely exists in mammals and birds. In order to reveal whether the MDB is universally existing in amniota of vertebrates, we explored the existence and the morphological features of the MDB in the Trachemys scripta elegans. Twenty fresh red-eared slider specimens were observed by the gross anatomy dissection and histological analysis. In the results, three kind of muscles in the postoccipital region of the red-eared slider were found. The rectus capitis dorsum minor muscle originated from the posterior margin of the occiput (C0) and terminated at the spinous process of the atlas (C1). The transversospinales muscle was attached to the vertebral arch and the postzygapophysis of the atlas and extended to the spinous process of the axis (C2). The C2-C3 intertransversales muscle were extended from the postzygapophysis of C2 and the one of C3. The three muscles covered the dorsal interspaces among C0-C3, and meantime they were closely connected with dense connective tissues, which filled in these interspaces. Each of these thick dense connective tissue membranes sent off several short and strong fibrous bundles ventrally to merge with the cervical spinal dura mater. Furthermore the connective tissues connecting these muscles with cervical spinal dura mater directly were revealed under the microscopy and they consisted of parallel and intensive collagen fibers with orientation from dorsal to ventral. In conclusion, this study for the first time demonstrated the existence of the MDB in the testudines, in all of the dorsal atlantooccipital, atlantoaxial and C2-C3 intervertebral spaces. Based on our results and comparative anatomical evidences in recent year, it could be inferred that the MDB might be its highly conserved structure in the evolution of amniota.

Se confirma que el puente miodural (PMD) conecta la mayoría de los músculos suboccipitales con la duramadre cervical a través de los espacios intervertebrales posteriores y existe ampliamente en mamíferos y aves. Para revelar si el MDB existe universalmente en la amniota de vertebrados, exploramos la existencia y las características morfológicas del PMD en Trachemys scripta elegans. Veinte muestras se observaron mediante disección anatómica y análisis histológico. En los resultados, se encontraron tres tipos de músculos en la región occipital. El músculo recto capitis dorsum minor se originó en el margen posterior del occipital (C0) y terminó en el proceso espinoso del atlas (C1). El músculo transverso espinal se unió al arco vertebral y el proceso del atlas y se extendió al proceso espinoso del axis (C2). El músculo intertransversario C2-C3 se extendió entre los procesos transversos de C2 y el de C3. Los tres músculos cubrían los espacios intermedios dorsales entre C0-C3 y, mientras tanto, estaban estrechamente conectados con tejidos conectivos densos, que rellenaban estos espacios. Cada una de estas membranas densas de tejido conectivo envían varios haces fibrosos cortos y fuertes ventralmente para fusionarse con la duramadre espinal cervical. Además, los tejidos conectivos que conectan estos músculos con la duramadre cervical y espinal se revelaron directamente bajo microscopía y consistían en intensas fibras de colágeno, paralelas, con orientación desde dorsal a ventral. En conclusión, este estudio demostró por primera vez la existencia del PMD en los estudios de prueba, en todos los espacios dorsales atlantooccipital, atlantoaxial e intervertebral C2-C3. Sobre la base de nuestros resultados y las evidencias anatómicas comparativas de los últimos años, se podría inferir que el PMD podría ser una estructura altamente conservada en la evolución de la amniota.

Pathological and cognitive changes in patients with type 2 diabetes mellitus and comorbid MCI and protective hypoglycemic therapies: a narrative review.

Type 2 diabetes mellitus (T2DM) is becoming a significant health issue worldwide. Many studies support the hypothesis that patients with T2DM have a higher-than-expected incidence of mild cognitive impairment (MCI) than individuals without diabetes. Based on the results from recent studies, MCI might be associated with the effects of T2DM on glucose metabolism and brain atrophy. As a narrative review, we will illuminate pathological and cognitive changes in patients with T2DM and comorbid MCI and protective hypoglycemic therapies. The early abnormal signs of cognition must be elucidated, and extensive investigations are needed to develop improved therapies for use in the clinic.

Anatomical parameters of the rectus capitis posterior major and obliqus capitis inferior muscles based on an oblique sagittal magnetic resonance scan method / Parámetros anatómicos de los músculos recto posterior mayor de la cabeza y oblicuo mayor de la cabeza basados en un método oblicuo sagital de exploración por resonancia magnética

The deep suboccipital muscles has been shown to connect the spinal dura mater via dense connective tissue termed the myodural bridge (MDB). The MDB has both physiological and clinical implications. Data on morphological and imaging anatomical parameters of the deep suboccipital muscles are scare. In this study, T2-weighted images of rectus capitis posterior major (RCPma) and obliqus capitis inferior (OCI) of 109 healthy adults were obtained by 0-degree sagittal and 30-degree oblique sagittal continuous MRI scanning of the head and neck of the subjects. Sectional area parameters of the RCPma and the OCI were measured. The 0-degree sagittal section was measured with 5 mm bias from the median sagittal plane, the sectional area of the RCPma was 186.34± 55.02 mm2 on the left, and 202.35± 59.76 mm2 on the right. The sectional area of OCI was 221.72± 68.99 mm2 on the left, and 224.92± 61.34 mm2 on the right; At the section with 30-degree bias from the oblique sagittal plane, the sectional area of RCPma was 183.30± 42.24 mm2 in males, and 133.05± 26.44 mm2 in females. The sectional area of OCI was 254.81± 46.20 mm2 in males, and 167.42± 27.85 mm2 in females. Significant sex difference exists in the sectional areas of the RCPma and OCI, the values of the male subjects were predominantly larger (P < 0.05), however there were no age- related significant difference. The sectional area of RCPma is bilateral asymmetric, the RCPma on the right side is larger than that of the left side (P < 0.05), but the OCI is bilaterally symmetric (P >0.05). The MRI image features, imaging anatomical data and sexual dimorphism of the RCPma and the OCI are presented in this study. This imaging anatomical data will be useful for functional and clinical studies on the RCPma, OCI, and the MDB.

Se ha demostrado que los músculos suboccipitales profundos conectan la duramadre espinal a través del tejido conectivo denso denominado puente miodural (PMD). El PMD tiene implicaciones tanto fisiológicas como clínicas. Los datos sobre los parámetros anatómicos y morfológicos y de imagen de los músculos suboccipitales profundos son alarmantes. En este estudio, se obtuvieron imágenes ponderadas en T2 del músculo recto posterior mayor (RCPma) y del músculo oblicuo mayor de la cabeza (OCI) de 109 adultos sanos, mediante una exploración de la cabeza y el cuello sagital de 0 grados y sagital oblicua de 30 grados. Se midieron los parámetros de área seccional del RCPma y el OCI. La sección sagital de 0 grados se midió con un sesgo de 5 mm desde el plano mediano, el área de la sección de la RCPma fue 186,34 ± 55,02 mm2 a la izquierda y 202,35 ± 59,76 mm2 a la derecha. El área seccional de OCI fue 221.72 ± 68.99 mm2 a la izquierda y 224.92 ± 61.34 mm2 a la derecha. En la sección de 30 grados desde el plano sagital oblicuo, el área de la sección de RCPma fue de 183.30 ± 42.24 mm2 en los hombres, y 133.05 ± 26.44 mm2 en las mujeres. El área seccional de OCI fue de 254.81 ± 46.20 mm2 en varones y 167.42 ± 27.85 mm2 en mujeres. Existe una diferencia significativa según el sexo en las áreas seccionales de la RCPma y la OCI, los valores de los sujetos masculinos fueron predominantemente mayores (P <0.05). Sin embargo, no hubo diferencia significativa relacionada con la edad. El área de la sección de RCPma es bilateral asimétrica, la RCPma en el lado derecho es más grande que la del lado izquierdo (P <0.05), pero el OCI es bilateralmente simétrico (P> 0.05). Las características de la imagen de resonancia magnética, los datos anatómicos de imágenes y el dimorfismo sexual de la RCPma y la OCI se presentan en este estudio. Estos datos anatómicos de imágenes serán útiles para estudios funcionales y clínicos en RCPma, OCI y PMD.

Orientation and property of fibers of the myodural bridge in humans.

BACKGROUND CONTEXT: Studies over the past 20 years have revealed that there are fibrous connective tissues between the suboccipital muscles, nuchal ligament, and cervical spinal dura mater (SDM). This fibrous connection with the SDM is through the posterior atlanto-occipital or atlantoaxial interspaces and is called the myodural bridge (MDB). Researchers have inferred that the MDB might have important functions. It was speculated that the function of MDB might be related to proprioception transmission, keeping the subarachnoid space and the cerebellomedullary cistern unobstructed, and affecting the dynamic circulation of the cerebrospinal fluid. In addition, clinicians have found that the pathologic change of the MDB might cause cervicogenic or chronic tension-type headache. Previous gross anatomical and histologic studies only confirmed the existence of the MDB but did not reveal the fiber properties of the MDB. This is important to further mechanical and functional research on the MDB. PURPOSE: Multiple histologic staining methods were used in the present study to reveal the various origin and fiber properties of the MDB. Muscles and ligaments participating in forming the MDB at the posterior atlanto-occipital or atlantoaxial interspaces were observed, and the fiber properties of the MDB were confirmed. The present study provides a basis for speculating the tensile force values of the MDB on the SDM and a morphologic foundational work for exploring the physiological functions and clinical significances of the MDB. STUDY DESIGN: Anatomical and histologic analyses of suboccipital structures that communicate with the SDM at the posterior atlanto-occipital or atlantoaxial interspaces were carried out. METHODS: Multiple histologic staining methods were used to evaluate the histologic properties and composition of the MDB at the posterior atlanto-occipital or atlantoaxial interspaces in five formalin-fixed head-neck human specimens. RESULTS: The results show that the MDB traversing the atlanto-occipital interspace originated from the rectus capitis posterior minor (RCPmi). The MDB traversing the atlantoaxial interspace originated mainly from the RCPmi, rectus capitis posterior major, and obliquus capitis inferior. These fibers form the vertebral dural ligament in the atlantoaxial interspace and connect with SDM. The MDB is mainly formed by parallel running type I collagen fibers; thus, suboccipital muscle could pull SDM strongly through the effective force propagated by the MDB during head movement. CONCLUSIONS: Myodural bridge is mainly formed by parallel running type I collagen fibers; thus, it can transmit the strong pull from the diverse suboccipital muscles or ligaments during head movement. The results of the present study will serve as a basis for further biomechanical and functional MDB research.