Medial Horn Supporting Ligament in Asian Upper Eyelids

Abstract

The purpose of this study was to describe the medial horn supporting ligament (MHSL) attached to the medial horn of the levator aponeurosis. The authors examined 3 different groups of specimens: gross cadaveric samples, microscopic cadaveric samples and intraoperative samples from levator resections. In all eyelids in the gross cadaveric samples, the MHSL was attached from the superior to the medial surfaces of the medial horn, and ran deeper in the direction of the trochlea in the superior region. Furthermore, the MHSL continued to the Whitnall ligament and was partially attached to the trochlea. In the microscopic samples, the MHSL was located adjacent to the levator aponeurosis in all specimens. The MHSL was constituted by comparatively thick fibers with few smooth muscle fibers. Under the MHSL, another fibrous structure existed with minute fibers including much smooth muscle. In the intraoperative samples from levator resections, the MHSL was also observed in all specimens. The MHSL was released from the medial horn in the cases of lateral tarsal shifts, but not in cases without. The MHSL, an indicator of the medial margin of the levator aponeurosis, may provide support, tension and suspension to the medial margin of the medial horn, strengthening its fragility.

Levator Palpebrae Superioris: An Anatomical Update

“…7 The medial horn supporting ligament, which originates from the trochlea and partly continues to the Whitnall's ligament provides some support and suspension to the medial horn. 66 The lateral horn is also wider with an average width of 12.3 mm in comparison to that of medial horn at 6.0 mm. 7 As the levator aponeurosis is angulated 20 lateral to the sagittal plane, the bifurcation angle between the longitudinal axis of levator aponeurosis and the lateral horn is smaller, conferring the lateral horn with a greater magnitude of traction.…”

“…19 Dehiscence of the medial horn supporting ligament from the medial horn was also demonstrated in subjects with lateral tarsal shift. 66 In those cases, medial undercorrections were observed after levator resection, because of the weakened medial attachments. 9,19 Hence, the stronger lateral traction and the weaker mechanical support of the medial horn contribute to the undercorrection of medial palpebral fissure in blepharoptosis surgery.…”

Transcutaneous Blepharoptosis Surgery: Simultaneous Advancement of the Levator Aponeurosis and Müller’s Muscle (Levator Resection)

“…In addition, as the levator aponeurosis is narrow proximally and wider distally, the narrow part of the aponeurosis should be sutured in cases that require a significant advancement. The medial horn supporting ligament can be used as a marking point to the medial margin of the levator aponeurosis [20]. …”

Dissection of the Eyelid and Orbit with Modernised Anatomical Findings

“…The LPS muscle, Whitnall's ligament, lower positioned transverse ligament (LPTL) [11][12][13][14], medial horn supporting ligament (MHSL) [15], lacrimal gland and the continuation of the levator aponeurosis to the orbital septum are identified [16].…”

“…Detailed Anatomy: The MHSL connects the trochlea, Whitnall's ligament, medial horn of the levator aponeurosis and medial orbital rim [15]. The MHSL tightly attaches to the medial horn, but is loosened by involutional changes.…”