Demer Joseph L, Oh Sei Yeul, Clark Robert A, Poukens Vadims
Jules Stein Eye Institute, Department of Ophthalmology, David Geffen Medical School, University of California, Los Angeles, California, USA.
Invest Ophthalmol Vis Sci. 2003 Sep;44(9):3856-65. doi: 10.1167/iovs.03-0160.
This study was undertaken to investigate evidence for a connective tissue pulley constraining the path of the inferior oblique (IO) muscle.
From magnetic resonance images, the cross-sectional area, path, and orbital relationships of the human IO were determined in multiple gaze positions. Rectus pulleys were directly imaged with intravenous gadodiamide contrast. Images were compared with serial histologic sections of IO muscles of humans and monkeys.
The IO path from origin to the lateral border of the inferior rectus (IR) muscle was straight. Lateral to the IR, the IO curved to follow the globe. At the point of IR crossing, the IO moved anteriorly from infraduction to supraduction by approximately 53% of the IR insertion's travel. Gaze-related change in IO cross section was demonstrable near the IR center. The gaze-related inflection in IO path corresponded to its encirclement by a pulley consisting of a dense ring of collagen, stiffened by elastin and smooth muscle, and united with the IR pulley. Orbital layer fibers of the IO inserted on its pulley, the lateral rectus (LR) pulley, and associated connective tissues.
Like the rectus muscles, the human and monkey IO has a connective tissue pulley serving as its functional origin. The position of the IO pulley is influenced by its coupling to the actively moving IR pulley, whereas in turn the IO orbital layer inserts on and presumably shifts the IR and LR pulleys. These intercouplings facilitate implementation by rectus extraocular muscle suspensions of a commutative ocular motor plant.
本研究旨在调查结缔组织滑车对下斜肌（IO）走行路径产生约束作用的证据。
通过磁共振成像确定人IO在多个注视位的横截面积、走行路径及眼眶关系。使用静脉注射钆双胺造影剂直接对直肌滑车进行成像。将图像与人类和猴子IO肌肉的系列组织学切片进行比较。
IO从起点至下直肌（IR）外侧缘的走行路径是直的。在IR外侧，IO弯曲以跟随眼球。在IR交叉点处，IO从下转位至上转位时向前移动的距离约为IR附着点移动距离的53%。在IR中心附近可观察到与注视相关的IO横截面积变化。IO走行路径中与注视相关的拐点对应于其被一个滑车环绕，该滑车由致密的胶原环组成，经弹性蛋白和平滑肌加固，并与IR滑车相连。IO的眼眶层纤维插入其滑车、外直肌（LR）滑车及相关结缔组织。
与直肌一样，人类和猴子的IO有一个结缔组织滑车作为其功能起点。IO滑车的位置受其与主动运动的IR滑车耦合的影响，而反过来，IO眼眶层插入并可能使IR和LR滑车发生移位。这些相互耦合有助于通过直肌眼外肌悬吊术实现可交换眼球运动装置。
