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This study was conducted to determine the muscular arrangement of the human pyloric sphincter using a comprehensive approach that involved microdissection, histology, and microcomputed tomography (micro-CT). The stomachs of 80 embalmed Korean adult cadavers were obtained. In all specimens, loose muscular tissue of the innermost aspect of the sphincter wall ran aborally, forming the newly found inner longitudinal muscle bundles, entered the duodenum, and connected with the nearby circular bundles. In all specimens, approximately one-third of the outer longitudinal layer of the sphincter entered its inner circular layer, divided the circular layer into several parts, and finally connected with the circular bundles. Anatomical findings around the sphincter were confirmed in micro-CT images. The sphincter wall comprised three layers: an inner layer of longitudinal bundles, a middle layer of major circular and minor longitudinal bundles, and an outer layer of longitudinal bundles. The stomach outer longitudinal bundles were connected to the sphincter circular bundles. The inner longitudinal bundles of the sphincter were connected to the adjacent circular bundles of the duodenum., (© 2021. The Author(s).)

Purpose: The aim of this study was to determine the width of the fibers that extend from the orbicularis oculi muscle (OOc) to the upper lip, and the lateral and inferior lengths of the OOc at the lateral canthus level. Methods: The OOc was investigated in the 40 hemifaces of 20 Korean cadavers. The lateral fibers of the OOc (OOc lat) were traced to determine whether or not these fibers extended to the upper lip. Results: The OOc lat extended to the upper lip at the lateral canthus level in 31 of the 40 specimens (77.5%), whereas some inferolateral fibers of the OOc that extended to the upper lip were observed near the level of the lower margin of the OOc in the other 9 specimens (22.5%). The mean ± SD and maximum widths of the OOc lat that extended to the upper lip at the lateral canthus level were 6.9 ± 3.3 mm and 14.3 mm, respectively. Conclusion: The obtained data will be helpful to distinguish the muscles that underly the wrinkles around the lateral canthus for safer and more-efficient BoNT-A treatments for crow's feet. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to clarify the anatomical relationship of the procerus with the nose, especially focusing on the transverse part of the nasalis, the nasal ala, and the levator labii superioris alaeque nasi (LLSAN). Materials and methods: The 53 faces from Korean cadavers were examined anatomically. Results: The procerus originated from the superficial and deep layers in all specimens. Some fibers of the lateral part of the superficial layer extended to connect to the transverse part of the nasalis, while other such fibers extended to attach to the skin of the upper nasal ala in all specimens. The superficial and deep layers of the procerus merged and then intermingled with the frontalis. The anatomical relationship between the superficial layer of the procerus and the LLSAN was classified into the following two categories according to their connections. Some medial originating fibers of the LLSAN extended superomedially to blend in the area between the superficial layer of the procerus and the depressor supercilii (13.5%). And, some medial originating fibers of the LLSAN extended superomedially and then constituted the lateral portion of the superficial layer of the procerus (7.7%). Conclusion: This study has yielded crucial data for understanding the anatomical relationships and functions of the procerus in relation to the nose. They will be helpful when designing effective therapies involving botulinum toxin type A, performing various types of rhinoplasty and facial surgeries, and in electromyography analyses. [ABSTRACT FROM AUTHOR]

Purpose: The fibularis quartus muscle (FQ) is an accessory fibular muscle that can be found in humans, reportedly in up to 22 %. The aim of this study was to classify morphological patterns of the FQ and its anatomical variations. Methods: Eighty lower limbs of 40 formalin-fixed adult Korean cadavers were used in this study. Results: The FQ was present in 13 of 80 specimens (16.3 %). In two specimens, each specimen had two FQs with different origins and insertion sites. Thus, 15 cases of FQ were found in 13 specimens. The FQ originated from the fibularis brevis muscle (FB) in 12 cases (15 %). In these cases, the FQ arose either as a muscle or as a tendon. The muscle fibers of the FQ merged into a tendon (8 of 12 cases) that inserted variously into (1) the tendon of the FB (three cases, 3.8 %), (2) the lateral surface of calcaneus (two cases, 2.5 %), (3) the inferior peroneal retinaculum (two cases, 2.5 %), or (4) the dorsal surface of the base of fifth metatarsal bone (one case, 1.3 %). The FQ arose as a tendon from the FB in 4 of 12 cases. In three of the four cases, the FQ inserted into the lateral surface of calcaneus. The FQ arose from structures other than the FB (three cases, 3.8 %). Conclusion: The present study has demonstrated a new classification for the FQ and its anatomical variations, and provided detailed data for its accurate identification of a muscle and relevant surgical procedures. [ABSTRACT FROM AUTHOR]