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Swords A, Cramberg M, Parker S, Scott A, Sopko S, Taylor E, Young BA. The Crocodylian proatlas functions to redistribute venous blood and cerebrospinal fluid. J Morphol 2024; 285:e21683. [PMID: 38424675 DOI: 10.1002/jmor.21683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 01/27/2024] [Accepted: 02/20/2024] [Indexed: 03/02/2024]
Abstract
The proatlas, a bone located between the skull and the neural spines of the cervical vertebrae, is best known from reptiles. Most previous studies of the proatlas have centered on its developmental, debating the relationship between the proatlas and the cervical neural arches. The present study was intended as a description of the proatlas in the American alligator (Alligator mississippiensis) and an experimental test of its hypothesized role in venous blood and cerebrospinal fluid (CSF) distribution. In Alligator, the proatlas is chevron-shaped; ventrally it has a loose connection to the dorsal surface of the first cervical vertebrae, dorsally it has a robust elastic tissue tether on the otoccipital and supraoccipital bones. The ventral surface of the proatlas parallels the dorsal margin of the foramen magnum and rests on the dorsal surface of the spinal venous sinus. Experimental manipulation of the proatlas demonstrated that displacement of the proatlas causes pressure changes in both the spinal venous sinus and the enclosed spinal CSF. The results of this study represent the first demonstration of an explicit functional role for the proatlas, the circulation of fluids between the cranial and spinal compartments of the central nervous system.
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Affiliation(s)
- Annelise Swords
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Michael Cramberg
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Seth Parker
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Anchal Scott
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Stephanie Sopko
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Ethan Taylor
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Bruce A Young
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
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Parker S, Cramberg M, Scott A, Sopko S, Swords A, Taylor E, Young BA. On the spinal venous sinus of Alligator mississippiensis. Anat Rec (Hoboken) 2024. [PMID: 38323749 DOI: 10.1002/ar.25403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Revised: 01/17/2024] [Accepted: 01/19/2024] [Indexed: 02/08/2024]
Abstract
The epidural space of the American alligator (Alligator mississippiensis) is largely filled by a continuous venous sinus. This venous sinus extends throughout the trunk and tail of the alligator, and is continuous with the dural sinuses surrounding the brain. Segmental spinal veins (sl) link the spinal venous sinus (vs) to the somatic and visceral venous drainage. Some of these sl, like the caudal head vein along the occipital plate of the skull, are enlarged, suggesting more functional linkage. No evidence of venous valves or external venous sphincters was found associated with the vs; the relative scarcity of smooth muscle in the venous wall of the sinus suggests limited physiological regulation. The proatlas (pr), which develops between the occipital plate and C1 in crocodylians, is shaped like a neural arch and is fused to the dorsal surface of the vs. The present study suggests that the pr may function to propel venous blood around the brain and spinal cord. The vs effectively encloses the spinal dura, creating a tube-within-a-tube system with the (smaller volume) spinal cerebrospinal fluid (CSF). Changes in venous blood pressure, as are likely during locomotion, would impact dural compliance and CSF pressure waves propagating along the spinal cord.
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Affiliation(s)
- Seth Parker
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Michael Cramberg
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Anchal Scott
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Stephanie Sopko
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Annelise Swords
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Ethan Taylor
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Bruce A Young
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
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Yang H, Wei XS, Gong J, Du XM, Feng HB, Su C, Gilmore C, Yue C, Yu SB, Li C, Sui HJ. The relationship between myodural bridge, atrophy and hyperplasia of the suboccipital musculature, and cerebrospinal fluid dynamics. Sci Rep 2023; 13:18882. [PMID: 37919345 PMCID: PMC10622500 DOI: 10.1038/s41598-023-45820-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Accepted: 10/24/2023] [Indexed: 11/04/2023] Open
Abstract
The Myodural Bridge (MDB) is a physiological structure that is highly conserved in mammals and many of other tetrapods. It connects the suboccipital muscles to the cervical spinal dura mater (SDM) and transmits the tensile forces generated by the suboccipital muscles to the SDM. Consequently, the MDB has broader physiological potentials than just fixing the SDM. It has been proposed that MDB significantly contributes to the dynamics of cerebrospinal fluid (CSF) movements. Animal models of suboccipital muscle atrophy and hyperplasia were established utilizing local injection of BTX-A and ACE-031. In contrast, animal models with surgical severance of suboccipital muscles, and without any surgical operation were set as two types of negative control groups. CSF secretion and reabsorption rates were then measured for subsequent analysis. Our findings demonstrated a significant increase in CSF secretion rate in rats with the hyperplasia model, while there was a significant decrease in rats with the atrophy and severance groups. We observed an increase in CSF reabsorption rate in both the atrophy and hyperplasia groups, but no significant change was observed in the severance group. Additionally, our immunohistochemistry results revealed no significant change in the protein level of six selected choroid plexus-CSF-related proteins among all these groups. Therefore, it was indicated that alteration of MDB-transmitted tensile force resulted in changes of CSF secretion and reabsorption rates, suggesting the potential role that MDB may play during CSF circulation. This provides a unique research insight into CSF dynamics.
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Affiliation(s)
- Heng Yang
- Department of Anatomy, Dalian Medical University, Dalian, Liaoning, China
| | - Xiao-Song Wei
- Department of Anatomy, Dalian Medical University, Dalian, Liaoning, China
| | - Jin Gong
- Department of Anatomy, Dalian Medical University, Dalian, Liaoning, China
| | - Xue-Mei Du
- Department of Nuclear Medicine, The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
| | - Hong-Bo Feng
- Department of Nuclear Medicine, The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
| | - Chang Su
- The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
| | | | - Chen Yue
- Department of Gynecology ands Obstetrics, Affiliated Zhongshan Hospital of Dalian University, Dalian, Liaoning, China
| | - Sheng-Bo Yu
- Department of Anatomy, Dalian Medical University, Dalian, Liaoning, China
| | - Chan Li
- Department of Anatomy, Dalian Medical University, Dalian, Liaoning, China.
| | - Hong-Jin Sui
- Department of Anatomy, Dalian Medical University, Dalian, Liaoning, China.
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Song X, Gong J, Yu SB, Yang H, Song Y, Zhang XH, Zhang J, Hack GD, Li TL, Chi YY, Zheng N, Sui HJ. The relationship between compensatory hyperplasia of the myodural bridge complex and reduced compliance of the various structures within the cranio-cervical junction. Anat Rec (Hoboken) 2023; 306:401-408. [PMID: 35808865 PMCID: PMC10084404 DOI: 10.1002/ar.25040] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 05/24/2022] [Accepted: 06/30/2022] [Indexed: 01/25/2023]
Abstract
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.
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Affiliation(s)
- Xue Song
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Jin Gong
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Sheng-Bo Yu
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Heng Yang
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Yang Song
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Xu-Hui Zhang
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Jing Zhang
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Gary D Hack
- Department of Advanced Oral Sciences and Therapeutics, University of Maryland School of Dentistry, Baltimore, Maryland, USA
| | - Tai-Lai Li
- The Second Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
| | - Yan-Yan Chi
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Nan Zheng
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Hong-Jin Sui
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
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Li C, Yue C, Liu ZC, Gong J, Wei XS, Yang H, Gilmore C, Yu SB, Hack GD, Sui HJ. The relationship between myodural bridges, hyperplasia of the suboccipital musculature, and intracranial pressure. PLoS One 2022; 17:e0273193. [PMID: 36054096 PMCID: PMC9439232 DOI: 10.1371/journal.pone.0273193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 08/04/2022] [Indexed: 11/23/2022] Open
Abstract
During mammalian evolution, the Myodural Bridges (MDB) have been shown to be highly conserved anatomical structures. However, the putative physiological function of these structures remains unclear. The MDB functionally connects the suboccipital musculature to the cervical spinal dura mater, while passing through the posterior atlanto-occipital and atlanto-axial interspaces. MDB transmits the tensile forces generated by the suboccipital muscles to the cervical dura mater. Moreover, head movements have been shown to be an important contributor to human CSF circulation. In the present study, a 16-week administration of a Myostatin-specific inhibitor, ACE-031, was injected into the suboccipital musculature of rats to establish an experimental animal model of hyperplasia of the suboccipital musculature. Using an optic fiber pressure measurement instrument, the present authors observed a significant increase in intracranial pressure (ICP) while utilizing the hyperplasia model. In contrast, surgically severing the MDB connections resulted in a significant decrease in intracranial pressure. Thus, these results indicated that muscular activation of the MDB may affect CSF circulation, suggesting a potential functional role of the MDB, and providing a new research perspective on CSF dynamics.
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Affiliation(s)
- Chan Li
- Department of Anatomy, Dalian Medical University, Dalian, China
| | - Chen Yue
- Department of Gynecology and Obstetrics, The Second Hospital of Dalian Medical University, Dalian, China
| | - Zhao-Chang Liu
- Department of Anatomy, Dalian Medical University, Dalian, China
| | - Jin Gong
- Department of Anatomy, Dalian Medical University, Dalian, China
| | - Xiao-Song Wei
- Department of Anatomy, Dalian Medical University, Dalian, China
| | - Heng Yang
- Department of Anatomy, Dalian Medical University, Dalian, China
| | - Campbell Gilmore
- Medical School, St. George’s University of London, London, United Kingdom
| | - Sheng-Bo Yu
- Department of Anatomy, Dalian Medical University, Dalian, China
| | - Gary D. Hack
- Department of Advanced Oral Sciences and Therapeutics, University of Maryland, Baltimore, Maryland, United States of America
- * E-mail: (HJS); (GDH)
| | - Hong-Jin Sui
- Department of Anatomy, Dalian Medical University, Dalian, China
- * E-mail: (HJS); (GDH)
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6
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Zhuang J, Gong J, Hack GD, Chi YY, Song Y, Yu SB, Sui HJ. A new concept of the fiber composition of cervical spinal dura mater: an investigation utilizing the P45 sheet plastination technique. Surg Radiol Anat 2022; 44:877-882. [PMID: 35715572 PMCID: PMC9246786 DOI: 10.1007/s00276-022-02962-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 05/09/2022] [Indexed: 12/03/2022]
Abstract
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.
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Affiliation(s)
- Jing Zhuang
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, 9 West Section, Lushun South Road, Dalian, 116044, People's Republic of China
| | - Jin Gong
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, 9 West Section, Lushun South Road, Dalian, 116044, People's Republic of China
| | - Gary D Hack
- Department of Advanced Oral Sciences and Therapeutics, University of Maryland School of Dentistry, Baltimore, MD, 21201, USA
| | - Yan-Yan Chi
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, 9 West Section, Lushun South Road, Dalian, 116044, People's Republic of China
| | - Yang Song
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, 9 West Section, Lushun South Road, Dalian, 116044, People's Republic of China
| | - Sheng-Bo Yu
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, 9 West Section, Lushun South Road, Dalian, 116044, People's Republic of China.
| | - Hong-Jin Sui
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, 9 West Section, Lushun South Road, Dalian, 116044, People's Republic of China.
- Expert Workstation, Dalian Hoffen Preservation Technique Institution, Dalian, 116052, China.
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Grondel B, Cramberg M, Greer S, Young BA. The morphology of the suboccipital region in snakes, and the anatomical and functional diversity of the myodural bridge. J Morphol 2021; 283:123-133. [PMID: 34783076 DOI: 10.1002/jmor.21431] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 11/10/2021] [Accepted: 11/13/2021] [Indexed: 12/23/2022]
Abstract
The myodural bridge, that is, skeletal muscle fibers attaching to the cervical dura mater, has been described from a variety of mammals and other amniotes. To test an earlier assumption about the presence of the myodural bridge in snakes, a comparative study was designed using a group of Colubrine snakes. Serial histological sections revealed no evidence of the myodural bridge in any of the snakes examined. Further analyses, including histology, computed tomography (CT), and micro-CT imaging of other distantly related snakes, also turned up no evidence of a myodural bridge. The close apposition of adjacent neural arches in snakes may preclude muscle tendons from passing through the intervertebral joint to reach the spinal dura. It is hypothesized that the myodural bridge functions in the clearance of the cerebrospinal fluid (CSF) by creating episodic CSF pressure pulsations, and that snakes are capable of creating equivalent CSF pressure pulsations through vertebral displacement.
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Affiliation(s)
- Bryson Grondel
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Michael Cramberg
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Skye Greer
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Bruce A Young
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
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Zhang ZX, Gong J, Yu SB, Li C, Sun JX, Ding SW, Ma GJ, Sun SZ, Zhou L, Hack GD, Zheng N, Sui HJ. A specialized myodural bridge named occipital-dural muscle in the narrow-ridged finless porpoise (Neophocaena asiaeorientalis). Sci Rep 2021; 11:15485. [PMID: 34326428 PMCID: PMC8322066 DOI: 10.1038/s41598-021-95070-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 07/19/2021] [Indexed: 11/25/2022] Open
Abstract
A dense bridge-like tissue named the myodural bridge (MDB) connecting the suboccipital muscles to the spinal dura mater was originally discovered in humans. However, recent animal studies have revealed that the MDB appears to be an evolutionarily conserved anatomic structure which may have significant physiological functions. Our previous investigations have confirmed the existence of the MDB in finless porpoises. The present authors conducted research to expound on the specificity of the MDB in the porpoise Neophocana asiaeorientalis (N.asiaeorientalis). Five carcasses of N.asiaeorientalis, with formalin fixation, were used for the present study. Two of the carcasses were used for head and neck CT scanning, three-dimensional reconstructions, and gross dissection of the suboccipital region. Another carcass was used for a P45 plastination study. Also, a carcass was used for a histological analysis of the suboccipital region and also one was used for a Scanning Electron Microscopy study. The results revealed that the MDB of the N.asiaeorientalis is actually an independent muscle originating from the caudal border of the occiput, passing through the posterior atlanto-occipital interspace, and then attaches to the cervical spinal dura mater. Thus the so called MDB of the N.asiaeorientalis is actually an independent and uniquely specialized muscle. Based on the origin and insertion of this muscle, the present authors name it the ‘Occipital-Dural Muscle’. It appears that the direct pull of this muscle on the cervical spinal dura mater may affect the circulation of the cerebrospinal fluid by altering the volume of the subarachnoid space via a pumping action.
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Affiliation(s)
- Zhao-Xi Zhang
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Jin Gong
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Sheng-Bo Yu
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Chan Li
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Jing-Xian Sun
- College of Fisheries and Life Science, Dalian Ocean University, Dalian, China
| | - Shuai-Wen Ding
- Department of Engineering Mechanics, Dalian University of Technology, Dalian, China
| | - Guo-Jun Ma
- Department of Engineering Mechanics, Dalian University of Technology, Dalian, China
| | - Shi-Zhu Sun
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Lin Zhou
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Gary D Hack
- Department of Advanced Oral Sciences and Therapeutics, University of Maryland School of Dentistry, Baltimore, MD, USA
| | - Nan Zheng
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China.
| | - Hong-Jin Sui
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China. .,Dalian Hoffen Preservation Technique Institution, Dalian, China.
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Xu Q, Shao CX, Zhang Y, Zhang Y, Liu C, Chen YX, Wang XM, Chi YY, Yu SB, Sui HJ. Head-nodding: a driving force for the circulation of cerebrospinal fluid. Sci Rep 2021; 11:14233. [PMID: 34244586 PMCID: PMC8270937 DOI: 10.1038/s41598-021-93767-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 06/24/2021] [Indexed: 11/28/2022] Open
Abstract
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.
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Affiliation(s)
- Qiang Xu
- Department of Anatomy, Dalian Medical University, Dalian, 116044, China.,Department of Radiology, The 967 Hospital of the Joint Logistics Support Force of PLA, Dalian, 116021, China
| | - Chang-Xi Shao
- Department of Anatomy, Dalian Medical University, Dalian, 116044, China.,Department of Anesthesiology, Baishan Municipal Central Hospital, Baishan, 134300, China
| | - Ying Zhang
- Graduate School, Dalian Medical University, Dalian, 116044, China
| | - Yu Zhang
- Graduate School, Dalian Medical University, Dalian, 116044, China
| | - Cong Liu
- Department of Anatomy, Dalian Medical University, Dalian, 116044, China.,Department of Radiology, The 967 Hospital of the Joint Logistics Support Force of PLA, Dalian, 116021, China
| | - Yu-Xiao Chen
- Graduate School, Dalian Medical University, Dalian, 116044, China
| | - Xue-Mei Wang
- Department of Radiology, Dalian Municipal Central Hospital, Dalian, 116033, China
| | - Yan-Yan Chi
- Department of Anatomy, Dalian Medical University, Dalian, 116044, China
| | - Sheng-Bo Yu
- Department of Anatomy, Dalian Medical University, Dalian, 116044, China.
| | - Hong-Jin Sui
- Department of Anatomy, Dalian Medical University, Dalian, 116044, China.
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10
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The morphology, biomechanics, and physiological function of the suboccipital myodural connections. Sci Rep 2021; 11:8064. [PMID: 33850172 PMCID: PMC8044117 DOI: 10.1038/s41598-021-86934-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 03/16/2021] [Indexed: 11/16/2022] Open
Abstract
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.
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Chen C, Yu SB, Chi YY, Tan GY, Yan BC, Zheng N, Sui HJ. Existence and features of the myodural bridge in Gentoo penguins: A morphological study. PLoS One 2021; 16:e0244774. [PMID: 33831002 PMCID: PMC8031436 DOI: 10.1371/journal.pone.0244774] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/23/2021] [Indexed: 12/03/2022] Open
Abstract
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.
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Affiliation(s)
- Cheng Chen
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Sheng-bo Yu
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Yan-yan Chi
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Guang-yuan Tan
- Haichang Ocean Park Holdings., Ltd, Biological Conservation Center, Shanghai, China
| | - Bao-cheng Yan
- Haichang Ocean Park Holdings., Ltd, Biological Conservation Center, Shanghai, China
| | - Nan Zheng
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
- * E-mail: (HJS); (NZ)
| | - Hong-Jin Sui
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
- Dalian Hoffen Preservation Institution, Dalian, China
- * E-mail: (HJS); (NZ)
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Abstract
BACKGROUND Because the anatomic mechanisms underlying the formation of the midcheek groove are unclear, treatments to date have resulted in unsatisfactory outcomes. OBJECTIVE This study investigated the anatomical foundation of the midcheek groove and evaluated appropriate treatment methods. MATERIALS AND METHODS Six cadaver hemifacial specimens were subjected to gross anatomic dissection and 6 to P45 sheet plastination. Based on the anatomic results, the area under the orbicularis oculi muscle (OOM) was selected for deep filling. Patients were evaluated by measuring 3D depth, regrading, and self-assessment. RESULTS The medial band was observed to be an important structure of the OOM, with the facial projection overlapping the midcheek groove trace. Two of the 6 P45 specimens were found to have compact fibroelastic bundles (CFBs) between the medial band and the dermis. Deep filling of the area under the OOM significantly reduced the depth of each section in all 34 patients (p < .001). Grades 3 and 4 midcheek grooves were downgraded distinctively. Most subjects expressed satisfaction with outcomes. CONCLUSION Formation of the midcheek groove is associated with the passage of CFBs. Deep filling of the area under the OOM effectively improves the midcheek grooves.
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Young BA, Adams J, Beary JM, Mardal KA, Schneider R, Kondrashova T. The myodural bridge of the American alligator ( Alligator mississippiensis) alters CSF flow. J Exp Biol 2020; 223:jeb230896. [PMID: 33077640 DOI: 10.1242/jeb.230896] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 10/11/2020] [Indexed: 12/19/2022]
Abstract
Disorders of the volume, pressure or circulation of the cerebrospinal fluid (CSF) lead to disease states in both newborns and adults; despite this significance, there is uncertainty regarding the basic mechanics of the CSF. The suboccipital muscles connect to the dura surrounding the spinal cord, forming a complex termed the 'myodural bridge'. This study tests the hypothesis that the myodural bridge functions to alter the CSF circulation. The suboccipital muscles of American alligators were surgically exposed and electrically stimulated simultaneously with direct recordings of CSF pressure and flow. Contraction of the suboccipital muscles significantly changed both CSF flow and pressure. By demonstrating another influence on CSF circulation and pulsatility, the present study increases our understanding of the mechanics underlying the movement of the CSF.
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Affiliation(s)
- Bruce A Young
- Department of Anatomy, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO 63501, USA
| | - James Adams
- Department of Anatomy, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO 63501, USA
| | - Jonathan M Beary
- Department of Behavioral Neuroscience, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO 63501, USA
| | | | - Robert Schneider
- Department of Family Medicine, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO 63501, USA
| | - Tatyana Kondrashova
- Department of Family Medicine, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO 63501, USA
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Scanning Electron Microscopic Observation of Myodural Bridge in the Human Suboccipital Region. Spine (Phila Pa 1976) 2020; 45:E1296-E1301. [PMID: 32796464 DOI: 10.1097/brs.0000000000003602] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN A scanning electron microscopic study performed on three cadaveric specimens focused on the human suboccipital region, specifically, myodural bridge (MDB). OBJECTIVE This study showed the connection form of the MDB among the suboccipital muscles, the posterior atlanto-occipital membrane (PAOM) and the spinal dura mater (SDM), and provided an ultrastructural morphological basis for the functional studies of the MDB. SUMMARY OF BACKGROUND DATA Since the myodural bridge was first discovered by Hack, researches on its morphology and functions had been progressing continuously. However, at present, research results about MDB were still limited to the gross anatomical and histological level. There was no research report showing the MDB's ultrastructural morphology and its ultrastructural connection forms between PAOM and SDM. METHODS A scanning electron microscope (SEM) was used to observe the connection of myodural bridge fibers with PAOM and SDM in atlanto-occipital and atlanto-axial interspaces, and the connection forms were analyzed. RESULTS Under the SEM, it was observed that there were clear direct connections between the suboccipital muscles and the PAOM and SDM in the atlanto-occipital and atlanto-axial spaces. These connections were myodural bridge. The fibers of the myodural bridge merged into the spinal dura mater and gradually became a superficial layer of the spinal dura mater. CONCLUSION MDB fibers merged into the SDM and became part of the SDM in the atlanto-occipital and atlanto-axial space. MDB could transfer tension and pulling force to the SDM effectively, during the contraction or relaxation of the suboccipital muscles. LEVEL OF EVIDENCE N/A.
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Dou YR, Zheng N, Gong J, Tang W, Okoye CS, Zhang Y, Chen YX, Zhang Y, Pi SY, Qu LC, Yu SB, Sui HJ. Existence and features of the myodural bridge in Gallus domesticus: indication of its important physiological function. Anat Sci Int 2018; 94:184-191. [PMID: 30552641 DOI: 10.1007/s12565-018-00470-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 11/22/2018] [Indexed: 12/15/2022]
Abstract
The myodural bridge (MDB) is a dense connective tissue that connects muscles with the cervical spinal dura mater via the posterior atlanto-occipital and atlato-axial interspaces. To date, the physiological function of the MDB has not been fully elucidated. Recent studies have identified the presence of the MDB in mammals, but very little information is available on the existence of the MDB in avifauna. We selected Gallus domesticus to explore the existence and the fiber property of the MDB in avifauna. We found that in this species, fibers originating from the ventral aspect of the rectus capitis dorsal minor are fused with the dorsal atlanto-occipital membrane and that numerous trabeculae connect the dorsal atlanto-occipital membrane with the cervical spinal dura mater. Furthermore, the occipital venous sinus is located between the trabeculae. The MDB is mainly composed of collagen type I fibers. Our results show that the MDB is present in G. domesticus and lead us to infer that the MDB is a highly conservative evolutionary structure which may play essential physiological roles.
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Affiliation(s)
- Ya-Ru Dou
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Nan Zheng
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Jing Gong
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | - Wei Tang
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China
| | | | - Ying Zhang
- The Second Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Yu-Xiao Chen
- The First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Yu Zhang
- The Second Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Shi-Yi Pi
- The First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Lian-Cong Qu
- The First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Sheng-Bo Yu
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China.
| | - Hong-Jin Sui
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, China. .,Dalian Hoffen Preservation Institution, Dalian, China.
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Okoye CS, Zheng N, Yu SB, Sui HJ. The myodural bridge in the common rock pigeon (Columbia livia): Morphology and possible physiological implications. J Morphol 2018; 279:1524-1531. [PMID: 30284324 DOI: 10.1002/jmor.20890] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 07/16/2018] [Accepted: 08/03/2018] [Indexed: 11/09/2022]
Abstract
The dense connective tissue that connects muscles to the cervical spinal dura mater is known as the myodural bridge in human anatomy and has been a subject of interest to anatomists and clinicians. The myodural bridge was originally discovered in humans, and also has been observed in other mammals and in reptilian sauropsids. We investigated the existence of the myodural bridge in a bird, that is, the Common Rock Pigeon Columba livia, to expand the understanding of the structure and function of the myodural bridge. Gross anatomical dissection of seven specimens and histological analyses of the suboccipital region of eight specimens were performed. The rectus capitis dorsalis minor muscle joins occipital periosteal extensions and inserts with several dense connective tissue cords on the dorsal side of the dura mater of the cervical spinal cord. The myodural bridge consists primarily of collagen Type I fibres, suggesting that the myodural bridge can transmit strong tensional forces generated by the contraction of M. rectus capitis dorsalis minor to the dura mater. The pull on the dura mater may affect the circulation of the cerebrospinal fluid in the subarachnoid space of the spine.
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Affiliation(s)
- Chukwuemeka Samuel Okoye
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, P. R. China
| | - Nan Zheng
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, P. R. China
| | - Sheng-Bo Yu
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, P. R. China
| | - Hong-Jin Sui
- Department of Anatomy, College of Basic Medicine, Dalian Medical University, Dalian, P. R. China
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Abstract
Recent studies have identified that the myodural bridge (MDB) is located between the suboccipital muscles and cervical dura mater in the posterior atlanto-occipital interspace within humans. The myodural bridge has been considered to have a significant role in physiological functions. However, there is little information about the myodural bridge in marine mammals; we conducted this study to investigate and examine the morphology of the myodural bridge in a sperm whale. We also aim to discuss the physiological functions of the myodural bridge. In this study, a 15.1-meter long sperm whale carcass was examined. Multiple methods were conducted to examine the bridges of the sperm whale which included dissection, P45 plastination and histological analysis. This study confirmed the existence of the myodural bridge in the sperm whale and shows there are two types of the bridge in the sperm whale: one type was the occipital-dural bridge (ODB), the other type was the MDB. A large venous plexus was found within the epidural space and this venous plexus is thought to contain a great amount of blood when in deep water and thus the movements of suboccipital muscles could be a unique power source that drives cerebrospinal fluid circulation.
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