The malaris muscle: its morphological significance for sustaining the intraorbital structures

Abstract

The orbicularis oculi muscle, an important mimetic muscle, was investigated to ascertain its anatomical relation to facial aging-especially its orbital part (Oo). Previous studies of the distinct muscle bundles frequently found inferior to the Oo have provided various definitions, including that of the malaris muscle. This study aimed to examine these muscle bundles and clarify their function in facial aging. Twelve heads of Japanese cadavers (average age: 82.5 years old) were dissected to observe the muscles, focusing in particular on those in the periorbital region. Six specimens were further dissected from the inner surfaces to examine the patterns of facial nerve branches under the operating microscope. Histological examinations of two head halves were carried out to investigate the relationship between the muscle bundles and the intraorbital structures. Muscle bundles consisting of lateral, medial, and U-shaped suspending bundles were observed in the region inferior to the Oo. Lateral and suspending bundles were found in all specimens, while the medial bundles were noted in only 9 of 22 specimens. Some branches of the facial nerve penetrated through the lateral, medial, and suspending bundles. The relationship between the suspending bundles and the protruding orbital fat was assessed. The muscle bundles found in this study were regarded as the malaris muscle-a transitional muscle between the superficial and deep facial layers. The suspending bundle may play a role in sustaining the intraorbital structures.

The malaris muscle concept reconsidered

“…It is apparent that in general the malaris muscle is currently perceived comprising the lateral muscle bundle inclining downwards medially [2141519], the medial muscle bundle inclining downwards laterally mentioned in the studies of Henle [10] and Lightoller [11]. The suspending bundle has not been mentioned until the latest study of Kampan et al [16].…”

“…The detail of the medial bundle is scarce, however the studies that revealed the anatomical description of the medial bundle exist [101116]. The medial bundle of the malaris muscle was described as the muscle bundle adhering medially to the orbital part of the orbicularis oculi muscle and running downwards laterally.…”

“…The medial bundle of the malaris muscle was described as the muscle bundle adhering medially to the orbital part of the orbicularis oculi muscle and running downwards laterally. All reviewed studies noted the medial bundle of the malaris muscle attaching from the frontal process of the maxilla [101116]. In addition, the medial palpebral ligament and the frontal belly of the occipitofrontalis muscle were indicated as the common attachments of the medial bundle of the malaris muscle [1116].…”

“…Thenceforth numerous studies have attempted to investigate the existence of the malaris muscle according to the studies of Henle [10] and Lightoller [11] as well as its aesthetic facial clinical implications. Although the studies each reported a similar relationship between the malaris muscle and facial aging appearance [111213141516]; in the anatomical context, however, the understanding of the malaris muscle remains inconclusive. Many studies have explained the malaris muscle that is the muscle bundle located lateral to the orbital part of the orbicularis oculi muscle [1415], while some have stated that the malaris muscle is merely the variation or part of the orbicularis oculi muscle [12131718].…”

“…Many studies have explained the malaris muscle that is the muscle bundle located lateral to the orbital part of the orbicularis oculi muscle [1415], while some have stated that the malaris muscle is merely the variation or part of the orbicularis oculi muscle [12131718]. However, a recent study of the malaris muscle mentioned the medial and lateral bundles of the malaris muscle together [16].…”