Medial Canthal Support Structures

Abstract

The medial canthus is supported by several structures with a complicated 3-dimensional arrangement in a narrow space. Although the medial canthal tendon occupies a major portion of the area, the medial canthal support structures include the following entities: Horner's muscle, the medial rectus capsulopalpebral fascia including the medial check ligament, the medial horn of the levator aponeurosis, the medial horn supporting ligament, the medial horn of the lower eyelid retractors, the preseptal part of the orbicularis oculi muscle, and 3 variations of the Lockwood's ligament. We named the composite of these structures the "medial retinaculum," which is similar to the "lateral retinaculum" of the lateral canthus. Profound comprehension and consideration of the medial retinaculum warrants safe and effective surgery in the medial canthal region.

Novel Evidence Concerning Lacrimal Sac Movement Using Ultra-High-Frequency Ultrasound Examinations of Lacrimal Drainage Systems

“…The lacrimal sac portion of the lacrimal pump has previously been thought to act like a pair of bellows, where the apex and the lateral wall of the lacrimal sac are pulled and pushed in the medial–lateral and cranial–caudal directions, creating alternating negative and positive pressure propelling the tears forward. 1,4 Our in vivo findings suggest that this theory must be reconsidered to account for the anterior–posterior movement and may lend support to the “wrung out” theory of active drainage proposed by Thale et al 6 after confirming helically arranged collagen fibers in the lacrimal sac wall. Recently, Ali et al 30 published an analysis of Horner’s muscle and its action on the canaliculi, providing new insights into the “canalicular pump mechanism.” The findings in this article, with the exception of an endoscopic video (see Video, Supplemental Digital Content 1, available at http://links.lww.com/IOP/A242) of the lacrimal sac discussed above, do not contradict our findings as they concern different parts of the LDS (canaliculi vs. lacrimal sac), but rather complement each other.…”

“…The current 2 main theories of active drainage, the "canalicular pump mechanism" and the "lacrimal sac pump mechanism," involve the action of the medial retinaculum (medial canthal tendon, Horner's muscle, the medial horn of the levator aponeurosis and the lower eyelid retractors, the medial rectus capsulopalpebral fascia, the preseptal part of the orbicularis oculi muscle, and Lockwood's ligament) on the canaliculi and the lacrimal sac. 1 During closing and opening of the eyelid, the medial retinaculum produces rhythmic lengthening and shortening of the canaliculi and compression and distention of the lacrimal sac in the medio-lateral and cranial-caudal directions, thereby alternately drawing tears into, and expelling them out of, the system. [1][2][3][4][5] The discovery of helically arranged collagen fibers in the lacrimal sac wall has led to an alternative theory that the lacrimal sac is "wrung out" during the blink cycle, rather than acting as a pair of bellows.…”

“…1 During closing and opening of the eyelid, the medial retinaculum produces rhythmic lengthening and shortening of the canaliculi and compression and distention of the lacrimal sac in the medio-lateral and cranial-caudal directions, thereby alternately drawing tears into, and expelling them out of, the system. [1][2][3][4][5] The discovery of helically arranged collagen fibers in the lacrimal sac wall has led to an alternative theory that the lacrimal sac is "wrung out" during the blink cycle, rather than acting as a pair of bellows. 6 However, both these theories are based on anatomical studies ex vivo, dacryocystoscintigraphy, lacrimal endoscopy, and measurements of pressure changes within the canaliculi and lacrimal sac and have not been confirmed in vivo under physiological conditions.…”

Morphological Changes in Faces Depending on Posture

“…The orbital region is strongly supported by the orbital rim bone, and the inner canthus area of the eye is strongly supported by the medial canthal tendon. 19 Therefore, the height of the orbit (or-os) barely changed, and the intercanthal width (en-en) changed only slightly at different positions. In contrast, the lateral canthus area is loosely supported by the lateral canthal tendon.…”

Medial Canthus Reconstruction with the Paramedian Forehead Flap

“…2 The medial canthal support structure also includes Horner's muscle, medial rectus capsulopalpebral fascia, the preseptal part of the orbicularis oculi muscle, and the medial horn of the levator aponeurosis. 3 Concerning the eyelid, there is the anterior portion composed of skin and muscles, the middle portion composed of the tarsal plate, which serves as the main structural component of the eyelid, and the posterior lamella. 4 Defects of the medial canthus require prompt suspicion of lacrimal injury, and as such, the puncta should be probed with a lacrimal probe.…”