Department of Ophthalmology, Erasmus Medical Center Rotterdam and Netherlands Institute for Neuroscience, Amsterdam.
Strabismus. 2020 Jun;28(2):109-113. doi: 10.1080/09273972.2020.1767480. Epub 2020 May 31.
Extraocular muscle pulley bands were described by Tenon in 1805 as "faisceaux tendineux" acting as "poulies de renvoi." The Passive and Active Pulley Hypotheses propose that these connective-tissue bands between muscle and bony orbital rim limit vertical shift of the horizontal rectus muscle belly in up- and downgaze, caused by the muscle's tendency to assume the shortest path from origin to insertion. The band's attachment to the muscle moves 20 mm sagittally when the eye looks from 50° left to 50° right, however, impeding vertical muscle stabilization. Sliding of the muscle in a sleeve would permit sagittal movement, but four anatomical studies could not confirm that. The band would have to be elastic: We measured it after orbital exenteration and found it to be slack, however, and once extended, very stiff. Our research group in Amsterdam suggested in 1984 that the retrobulbar fat and its enveloping connective-tissue sheets including the intermuscular membrane keep muscle bellies in place. We compared horizontal-rectus-muscle positions in up- and down-gaze using frontal CTs through the posterior pole of the eye. The bellies stayed in place while, anteriorly, the tendons bent up- and downward. We also found that the paths of horizontal rectus muscles were curved outwards in horizontal CTs. We surmised that retrobulbar pressure in the fat, resulting from four rectus muscles pulling the eyeball into the orbit, is contained by rectus muscles and connective-tissue sheets and that the resulting tension in the sheets keeps the muscles in place. Years later we repeated the CT study in a Crouzon patient whose bony orbital rim was displaced 2cm posteriorly, preventing pulley-band fixation to the bone: No vertical shift of horizontal rectus muscle bellies occurred in up- and down-gaze. Finally, we developed a mathematical finite-element model of orbit, muscles, fat and eyeball to study whether fat with enveloping connective-tissue sheets could keep eye muscles in place. In simulated eye movements, the retrobulbar fat, with low elasticity as found in vivo, not only kept the eyeball in place but also horizontal rectus muscle bellies in up- and down-gaze and vertical recti in left- and right-gaze.
眼外肌滑车带于 1805 年由 Tenon 描述为“腱束”，起到“返回滑轮”的作用。被动和主动滑车假说提出，这些连接在肌肉和骨性眶缘之间的结缔组织带限制了水平直肌腹在向上和向下注视时的垂直移位，这是由于肌肉倾向于从起点到止点走最短路径。当眼睛从 50°左侧看向 50°右侧时，带与肌肉的连接会在矢状面上移动 20mm，然而，这会阻碍垂直肌肉的稳定。肌肉在套管内滑动可以允许矢状运动，但四项解剖学研究无法证实这一点。带必须具有弹性：我们在眼眶内容物切除术后测量了它，发现它很松弛，但一旦伸展，就变得非常僵硬。我们在阿姆斯特丹的研究小组于 1984 年提出，眶内脂肪及其包裹的结缔组织片，包括肌间膜，使肌肉腹保持在适当的位置。我们使用穿过眼球后极的额部 CT 比较了上、下注视时水平直肌的位置。当肌腱向上和向下弯曲时，肌肉腹保持在适当的位置，而前部则向上和向下弯曲。我们还发现，在水平 CT 中，水平直肌的路径向外弯曲。我们推测，由于四条直肌将眼球拉入眼眶，眶内脂肪会产生压力，该压力被直肌和结缔组织片限制，而片内的张力使肌肉保持在适当的位置。多年后，我们在一位 Crouzon 患者中重复了 CT 研究，该患者的骨性眶缘向后移位 2cm，阻止了滑车带固定在骨头上：在向上和向下注视时，水平直肌腹没有发生垂直移位。最后，我们开发了一个眼眶、肌肉、脂肪和眼球的数学有限元模型，以研究是否带有包裹性结缔组织片的脂肪可以使眼外肌保持在适当的位置。在模拟眼球运动中，正如在体内发现的那样，具有低弹性的眶内脂肪不仅使眼球保持在适当的位置，而且使上、下注视时的水平直肌腹和左、右注视时的垂直直肌保持在适当的位置。
