Occipital-Dural Muscle: A Specialized Myodural Bridge in Narrow-Ridge Finless Porpoise (Neophocaena Asiaorientalis)

Abstract A dense bridge-like tissue named the myodural bridge (MDB) connecting the suboccipital muscles and the spinal dura mater was originally discovered in humans. Recent studies have revealed that the MDB confirmed a universal existing normal anatomical structure in mammals which is considered being significant in physiological functions. Our previous investigations have confirmed the existence of MDB in the finless porpoises. We conduct this research to expound the specificity of the MDB in Neophocana asiaeorientalis (N.asiaeorientalis). Five carcasses of N.asiaeorientalis with formalin fixation were used for this study. Two were used for head and neck CT scanning, three-dimensional reconstruction, and dissection of suboccipital region. One was used for P45 plastinated sheets observation. One was for histological analysis of suboccipital region. One was for Scanning electron microscopic study. The results showed that the MDB in N.asiaeorientalis is an independent muscle originated from the caudal border of occiput, directly extended through the posterior atlanto-occipital interspace and connected with the cervical spinal dura mater. Thus the MDB in N.asiaeorientalis is an independent and specialized muscle. Based on the origin and termination of this muscle, we could name it as ‘Occipital-Dural Muscle’. And the direct pull on the cervical spinal dura mater might affect the circulation of the cerebrospinal fluid (CSF) by altering the volume of subarachnoid space of spine.

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A specialized myodural bridge named occipital-dural muscle in the narrow-ridged finless porpoise (Neophocaena asiaeorientalis)

Scientific Reports ◽

10.1038/s41598-021-95070-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Zhao-Xi Zhang ◽

Jin Gong ◽

Sheng-Bo Yu ◽

Chan Li ◽

Jing-Xian Sun ◽

...

Keyword(s):

Dura Mater ◽

Animal Studies ◽

Histological Analysis ◽

Three Dimensional ◽

Ct Scanning ◽

Microscopy Study ◽

Electron Microscopy Study ◽

Anatomic Structure ◽

Evolutionarily Conserved ◽

Myodural Bridge

AbstractA 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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