Magnetic resonance imaging of human extraocular muscles during static ocular counter-rolling
Magnetic resonance imaging of human extraocular muscles during static ocular counter-rolling
复制标题
DOI：
10.1152/jn.01157.2004
复制
发表时间：
2005-11-01
影响因子：
2.5
通讯作者：
Clark, RA
中科院分区：
文献类型：
--
作者：
Demer, JL;Clark, RA
眼外直肌（EOM）滑轮限制EOM路径。在头部不动的视觉固定期间，已知主动控制的滑轮保持位置，导致EOM拉动方向的变化是眼睛位置变化的一半。在注视、扫视和追逐过程中观察到的这种滑轮行为符合Listing’s law （LL）的眼扭转。然而，前庭-眼反射（VOR）期间的滑轮行为尚未得到研究。本实验研究了眼球反转（OCR），这是一种违反LL的静态扭转VOR，但可以在MRI中引起。在中心目标固定期间，对10名成年人进行了三平面MRI，同时将其定位在右侧和左侧下位，已知会引起静态OCR。根据区域质心确定EOM的截面和路径。利用路径对滑轮进行三维定位。下、中、上直肌滑轮组在冠状面从右到左平均4.1度（最大8.7度）反向旋转复位，显著（P < 0.025）。外直肌有平均1.4度的趋势。直肌滑轮阵列的扭转移位与上下斜肌明显的收缩截面改变有关。在OCR过程中，扭转直肌滑轮移位改变了直肌EOM的牵引方向，与直肌滑轮上已知的斜EOM轨道层插入有关。在静态OCR期间，滑轮重新配置的量大约是公布的眼扭转值的一半，这种安排将导致直肌牵拉方向的变化小于眼扭转量的一半。
The rectus extraocular muscle (EOM) pulleys constrain EOM paths. During visual fixation with head immobile, actively controlled pulleys are known to maintain positions causing EOM pulling directions to change by one-half the change in eye position. This pulley behavior is consistent with Listing's law (LL) of ocular torsion as observed during fixation, saccades, and pursuit. However, pulley behavior during the vestibulo-ocular reflex (VOR) has been unstudied. This experiment studied ocular counterrolling ( OCR), a static torsional VOR that violates LL but can be evoked during MRI. Tri-planar MRI was performed in 10 adult humans during central target fixation while positioned in right and left side down positions known to evoke static OCR. EOM cross-sections and paths were determined from area centroids. Paths were used to locate pulleys in three dimensions. Significant ( P < 0.025) counter-rotational repositioning of the rectus pulley arrays of both orbits was observed in the coronal plane averaging 4.1 degrees ( maximum, 8.7 degrees) from right to left side down positions for the inferior, medial, and superior rectus pulleys. There was a trend for the lateral rectus averaging 1.4 degrees. Torsional shift of the rectus pulley array was associated with significant contractile cross-section changes in the superior and inferior oblique muscles. Torsional rectus pulley shift during OCR, which changes pulling directions of the rectus EOMs, correlates with known insertions of the oblique EOM orbital layers on rectus pulleys. The amount of pulley reconfiguration is roughly one-half of published values of ocular torsion during static OCR, an arrangement that would cause rectus pulling directions to change by less than one-half the amount of ocular torsion.