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 present authors suggest that the MDB has important physiological functions in humans. 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. 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. While foraging, this penguin is able to reach speeds of up to 22 miles per hour. 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.

中文翻译：

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Gentoo企鹅肌膜桥的存在和特征：形态学研究

最近的研究证明，现在称为肌膜桥（MDB）的解剖结构将枕下肌肉组织连接到颈椎硬脊膜（SDM）。在人类中，MDB穿过后寰枕和后寰轴间隙。本作者建议，MDB在人类中具有重要的生理功能。先前已经验证了MDB在包括飞行鸟类（原鸽和家蝇）在内的各种哺乳动物中的存在。Gentoo企鹅是海洋鸟类，每天可以进行450次潜水，潜水深度可达660英尺。巴布亚企鹅也是世界上跳水最快的鸟类。因此，本研究旨在调查非飞行中的Gentoo企鹅（Pygoscelis papua）中MDB的存在和特征。可以潜水的海鸟。在觅食时，这种企鹅能够达到每小时22英里的速度。对于本研究，解剖了六个Gentoo企鹅标本，以观察其MDB的存在和组成。还进行了组织学染色以分析Gentoo企鹅中MDB的解剖关系和特征。在这项研究中，发现Gentoo企鹅的枕下肌肉组织由小直肌头炎背阔肌（RCDmi）和大直肌头炎背阔肌（RCDma）组成。观察到密集的结缔组织纤维将这两个枕下肌连接到脊硬脑膜（SDM）。这种致密的结缔组织桥主要由I型胶原纤维组成。因此，这只企鹅的MDB似乎与以前在人类中观察到的MDB类似。本研究证明，MDB不仅存在于企鹅中，而且还具有与飞鸟区分开的独特特征。因此，这项研究促进了对飞行中的海鸟中MDB形态特征的理解。