Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States.
Department of Clinical Science, Ophthalmology, Umeå University, Umeå, Sweden.
Invest Ophthalmol Vis Sci. 2018 Jan 1;59(1):322-329. doi: 10.1167/iovs.17-23003.
We examined the pattern and extent of connective tissue distribution in the extraocular muscles (EOMs) and determined the ability of the interconnected connective tissues to disseminate force laterally.
Human EOMs were examined for collagens I, III, IV, and VI; fibronectin; laminin; and elastin using immunohistochemistry. Connective tissue distribution was examined with scanning electron microscopy. Rabbit EOMs were examined for levels of force transmission longitudinally and transversely using in vitro force assessment.
Collagens I, III, and VI localized to the endomysium, perimysium, and epimysium. Collagen IV, fibronectin, and laminin localized to the basal lamina surrounding all myofibers. All collagens localized similarly in the orbital and global layers throughout the muscle length. Elastin had the most irregular pattern and ran longitudinally and circumferentially throughout the length of all EOMs. Scanning electron microscopy showed these elements to be extensively interconnected, from endomysium through the perimysium to the epimysium surrounding the whole muscle. In vitro physiology demonstrated force generation in the lateral dimension, presumably through myofascial transmission, which was always proportional to the force generated in the longitudinally oriented muscles.
A striking connective tissue matrix interconnects all the myofibers and extends, via perimysial connections, to the epimysium. These interconnections are significant and allow measurable force transmission laterally as well as longitudinally, suggesting that they may contribute to the nonlinear force summation seen in motor unit recording studies. This provides strong evidence that separate compartmental movements are unlikely as no region is independent of the rest of the muscle.
我们研究了眼外肌（EOM）中结缔组织的分布模式和范围，并确定了相互连接的结缔组织向侧面传播力的能力。
使用免疫组织化学方法检查了人眼外肌的 I、III、IV 和 VI 型胶原；纤连蛋白；层粘连蛋白；和弹性蛋白。使用扫描电子显微镜检查结缔组织的分布。使用体外力评估检查了兔眼外肌的纵向和横向力传递水平。
I、III 和 VI 型胶原定位于肌内膜、肌束膜和肌外膜。IV 型胶原、纤连蛋白和层粘连蛋白定位于环绕所有肌纤维的基底膜。所有胶原在整个肌肉长度的眶部和全球层中都有类似的定位。弹性蛋白的模式最不规则，沿长轴和周向贯穿所有眼外肌的长度。扫描电子显微镜显示这些元素广泛相互连接，从肌内膜通过肌束膜到环绕整个肌肉的肌外膜。体外生理学显示在横向维度产生力，可能通过肌筋膜传递，这与沿长轴定向的肌肉产生的力始终成正比。
一个引人注目的结缔组织基质将所有肌纤维相互连接，并通过肌束膜连接延伸到肌外膜。这些连接非常重要，允许横向和纵向进行可测量的力传递，这表明它们可能有助于在运动单位记录研究中看到的非线性力总和。这有力地证明了单独的隔室运动不太可能，因为没有一个区域是独立于肌肉的其余部分的。
