Dynamic Magnetic Resonance Imaging of the Levator palpebrae superioris Muscle

Abstract

The relationship between upper lid elevation (h) and shortening (s) of the levator palpebrae superioris muscle (LPS) has an influence on the dose-response relationship in ptosis surgery. In order to investigate the relationship between upper lid elevation and shortening of the LPS, parasagittal T₁-weighted MR images of the orbit were obtained in healthy subjects with the eye in down- and upgaze. The position of the upper lid margin and the length of the LPS were measured in the images in down- and upgaze and the amount of h and s was determined. For a mean (± SD) vertical upper lid elevation of 15 ± 1 mm, the mean (± SD) shortening of the LPS muscle was 21 ± 3 mm (n = 4). The mean ratio of h:s was calculated to be 1:1.4, which means that the levator muscle must contract by 1.4 cm in order to achieve a lid elevation of 1 cm. Therefore, the force of the LPS which is necessary to lift the upper eyelid can be smaller than the lid-closing force. This strongly suggests a physiological mechanism which reduces the muscle force necessary for lifting the upper eyelid.

Surgical anatomy and histology of the levator palpebrae superioris muscle for blepharoptosis correction

“…Our analysis of anatomical and topographic features of the LPS muscle has not shown any statistically significant differences compared to previous studies [5][6][7][8] .…”

Is Whitnall’s Ligament Responsible for the Curved Course of the Levator palpebrae superioris Muscle?

“…(2) As for other extraocular muscles [2], the muscle tension influences the course of the LPS: MRI scans performed in up-and downgaze demonstrate that the curvature of the LPS is more obvious during relaxation than during contraction of the muscle [6]. The curvature is even more marked in the presence of IIIrd nerve palsies (see fig.…”

“…Similar to the extraocular rectus muscles [2,3], the LPS also courses in a curved path and culminates a few millimeters cranial to the surface of the globe [4][5][6] (fig. 1).…”

Medial Horn Supporting Ligament in Asian Upper Eyelids

“…Hence, in accordance with the anatomical findings, we have named this ligament the "medial horn supporting ligament" (MHSL). Since the Whitnall ligament moves in conjunction with the LPS (Ettl et al, 1996(Ettl et al, , 1998, it also seems to provide superior tension to the medial horn, and as part of the MHSL is attached to the trochlea, this structure also seems to have a suspensory effect.…”