The universal existence of myodural bridge in mammals: an indication of a necessary function

Abstract

The “myodural bridge” was described in literatures as a dense fibrous tissue connecting the sub-occipital musculature with the spinal dura mater in human studies. Now the concept of “myodural bridge” was perceived as an exact anatomical structure presumably essential for critical physiological functions in human body, and might exist in other mammals as well. To determine the existence of the “myodural bridge” in other mammals and to lay a foundation for the functional study, we examined representatives in five different mammalian orders. Based on the anatomical dissections, P45 plastinated sections and histological sections, we found that a dense fibrous tissue connected the rectus capitisdorsalis minor and the spinal dura mater through the dorsal atlanto-occipital interspace with or without the medium of the posterior atlanto-occipital membrane. These observed connective tissues were very similar to the “myodural bridge” previously described in humans. We proposed that the “myodural bridge”, as an evolutionally conserved structure, presents in many other mammals. Moreover, we believed that the “myodural bridge” might be a homologous organ in mammals. Thus, this study could provide an insight for our understanding the physiological significance of the “myodural bridge”, especially in human.

The myodural bridge in the common rock pigeon (Columbia livia): Morphology and possible physiological implications

“…The myodural bridge refers to the dense connective tissue structure that connects the Ligamentum nuchae and M m. rectus capitis posterior minor, rectus capitis posterior major and obliquus capitis inferio r to the spinal dura mater through the atlanto‐occipital and atlanto‐axial interspaces (Hack et al, 1995; Zheng et al, 2014; Scali et al, ; Pontell et al, ). The existence of this structure in humans is supported by strong evidence (Palomeque‐del‐Cerro et al, ) and has been studied in domestic dogs, finless porpoise, rhesus monkey, rabbit, and rat (Zheng et al, ). Thus, it is assumed to be a common structure in placental mammals (Zheng et al, ).…”

“…The existence of this structure in humans is supported by strong evidence (Palomeque‐del‐Cerro et al, ) and has been studied in domestic dogs, finless porpoise, rhesus monkey, rabbit, and rat (Zheng et al, ). Thus, it is assumed to be a common structure in placental mammals (Zheng et al, ). The present study shows that the myodural bridge exists also in Columba livia .…”

“…Interestingly, we observed that the myodural bridge in Columbia livia and in the Siamese crocodile (Zhang et al, ) are similar. In these animals, the myodural bridge connecting with the cervical spinal dura mater are cord‐like dense connective tissues, whereas the myodural bridge of humans (Palomeque‐del‐Cerro et al, ) and other mammals (Zheng et al, ) consists of dense connective tissue occupying the epidural space. Archosaurs (i.e., birds and crocodiles) also have a similar internal vertebral venous plexus (IVVP) pattern.…”

“…It is a well‐documented anatomical structure in humans (Palomeque‐del‐Cerro et al, ; Yuan et al, ; Enix, Scali, & Pontell, ; Zheng et al, 2014; Pontell, Scali, Marshall, & Enix, ; Scali, Pontell, Enix, & Marshall, ; Mitchell, Humphreys, & O'Sullivan, ; Hack et al, 1995). A recent study revealed this structure also in five other mammalian taxa, that is, Macaca mulatta, Oryctolagus cuniculus, Canis familiaris, Felis catus, Ratus norvegicus, Cavia porcellus and Indoasian finless porpoise, and hypothesized that it may be widespread among mammals (Zheng et al, ). In addition, it was shown that the posterior occipital muscles insert on the dorsal side of the dura mater of the spinal cord by multiple trabeculae in the Siamese crocodiles, Crocodylus siamensis (Zhang et al, ).…”

Relationship between the sectional area of the rectus capitis posterior minor and the to be named ligament from 3D MR imaging

“…The myodural bridge (MDB) is a connective tissue band that connects the suboccipital muscles and nuchal ligament (NL) with the cervical spinal dura mater (SDM) [1][2][3][4][5][6]. It has been recently confirmed as a conserved structure in mammals [7][8][9]. The MDB has a critical role in transmitting tensile force from its muscular and ligamentous components to the SDM, which has an essential role in the etiology of headache and cervicocephalic pain syndrome [10][11][12][13][14].…”