Kwan-Hyun Youn

Clinical implications of the middle temporal vein with regard to temporal fossa augmentation.

BACKGROUND The middle temporal vein (MTV) traverses the temporal fossa between the superficial and deep layers of the deep temporal fascia. During filler injection into a deficient temporal fossa, filling agents may be inadvertently injected into the MTV, which results in vascular complications. OBJECTIVE To investigate the course of the MTV to enable safe filler injection in the temple area. MATERIALS AND MATERIALS The course and diameter of the MTV were measured in 18 hemifaces from 9 Korean cadavers. RESULTS The MTV was located 23.5 and 18.5 mm above the zygomatic arch at the jugale and the zygion, respectively. The diameter of the MTV at its thickest point was 5.1 mm. A splitting and reuniting pattern, such that the MTV occupied more space than a single trunk, was observed in 28% of cases. CONCLUSION We propose that the safest area for filler injection in temporal fossa augmentation is one finger width above the zygomatic arch.

An anatomical study of the insertion of the zygomaticus major muscle in humans focused on the muscle arrangement at the corner of the mouth.

Background: The aim of this study was to clarify the arrangement of the zygomaticus major muscle by means of topographic examination, and to evaluate the anatomical variations in the insertion of the zygomaticus major at the perioral region. Methods: After a detailed dissection in the modiolar region, the insertion area of the zygomaticus major was observed in 70 embalmed cadavers. Results: At the perioral region of the dissected specimens, the anatomical aspects of the muscular arrangement and attachment of the zygomaticus major muscle were classified into four categories. In type I, the superficial muscle band of the zygomaticus major is blended and interlaced with the levator anguli oris, whereas the fibers of the deep muscle band blend into the buccinator, passing deeper to the levator anguli oris; this was the situation most commonly encountered (54.3 percent). It was found that the insertion of the zygomaticus major was divided into superficial and deep bands (types I and IV) [42 cases (60 percent)] and into three layers of superficial, middle, and deep fibers (type II) [17 cases (24.3 percent)]. The others were cases where the zygomaticus major was inserted deep into the levator anguli oris as a single muscle band (type III) [11 cases (15.7 percent)]. Conclusion: The arrangement and insertion patterns of the zygomaticus major in this study are expected to provide critical information for surgical planning for the procedure of facial reanimation surgery.

New anatomical insight of the levator labii superioris alaeque nasi and the transverse part of the nasalis.

PurposeThe aim of this study was to clarify the morphology and topography of the deep layer of levator labii superioris alaeque nasi muscle (LLSAN) and the transverse part of the nasalis. Anatomical variations in the topographic relationships were also described to understand the function of the LLSAN and the transverse part of the nasalis.MethodsAnatomical dissections were performed on 40 specimens of embalmed Korean adult cadavers.ResultsThe LLSAN was divided into two layers, which were superficial and deep in the levator labii superioris muscle (LLS), respectively. The superficial layer of LLSAN descended on the LLS, and the deep layer was located deep in the LLS. The deep layer of LLSAN originated from the superficial layer of LLSAN and the frontal process of the maxilla. It inserted between the levator anguli oris and the orbicularis oris muscles. This transverse part of the nasalis received some muscle fibers from the superficial layer of LLSAN in 90% (36/40) of specimens. The transverse part of the nasalis originated from the maxilla and ascended, passing posterior to the superficial layer of LLSAN in 65% (26/40) of specimens. However, it originated as two muscle bellies from the maxilla and the upper half of the alar facial crease, respectively, in 35% (14/40) of specimens.ConclusionsThese findings will be crucial data to understand the structure and function of the LLSAN and the transverse part of the nasalis.

An Anatomic Study of the Bifid Zygomaticus Major Muscle

The dramatic changes in facial expression are most remarkable in the perioral region. Among the perioral musculatures, the zygomaticus major (ZMj) muscle plays an important role in the facial expression. The aim of this study was to determine the anatomic patterns of the bifid ZMj through a topographic examination at the perioral region. Through 70 dissections of the hemifaces, the insertion area of the ZMj was observed in 70 embalmed cadavers. The bifid ZMj was observed in 28 cases (40%). In most cases of the bifid ZMj, the superior muscle fibers were larger and wider than the inferior fibers. Bilateral bifid ZMj was found in 71.4% of the bifid ZMj specimens. The arrangement and insertion patterns of the ZMj in this study are expected to provide critical information for the surgical planning and procedure for facial reanimation surgery.

Neuroanastomosis and the innervation territory of the mental nerve

The aim of this study was to clarify the distribution pattern and innervation territory of the mental nerve (MN) in the skin and mucosa by topographic examination by Sihlers staining, thereby providing reference anatomical information for surgical procedures and to enable prediction of regions of sensory disturbance following nerve damage. Ten human specimens were subjected to Sihlers staining, which is a highly accurate method for visualizing the distribution of nerve fibers without altering their topography. Each branch of the MN overlapped adjacent branches (five cases), or else they were distributed individually at the lower lip (five cases). The MN anastomosed with some branches of the facial nerve near the mental foramen. Moreover, some branches of the MN anastomosed with the buccal nerve of the trigeminal nerve, which supplies sensation to the skin and mucosa over the lateral region of the lower lip (six cases). The details of the distribution pattern and innervations territory of the MN presented herein may enable the prediction of a region of sensory disturbance following MN damage. Moreover, knowledge of the pattern of synapses with adjacent branches of other nerves, such as the facial (marginal mandibular and cervical branches) and the buccal nerves, might help to improve our understanding around incomplete anesthesia during the surgical procedures in oral & maxillofacial region. Clin. Anat. 598–602, 2014.

New anatomical profile of the nasal musculature: Dilator naris vestibularis, dilator naris anterior, and alar part of the nasalis

The aim of this study was to clarify the morphology and topography of the dilator naris vestibularis, dilator naris anterior, and alar part of the nasalis. Anatomical variations in the topographic relationships are also described to provide critical data for understanding nasal muscular functions. Anatomical and histological examinations were performed on 40 specimens of embalmed Korean adult cadavers. The dilator naris vestibularis muscle (named by the present authors) was located between the external and vestibular skin of the alar lobule. The muscle fibers radiated along the dome‐shaped nasal vestibule. The dilator naris anterior muscle originated from the frontal surfaces of the lateral half of the lateral crus and the accessory alar cartilage adjacent to the lateral crus. The extent of the lower insertion of the dilator naris anterior muscle was at the alar groove. The alar part of the nasalis originated with the transverse part of nasalis from the maxilla. It ascended to attach to the alar crease and the adjacent deep surface of external skin of the alar lobule. These findings may provide anatomical knowledge required to understand the structure and function of these nasal muscles such as during rhinoplasty or other surgery of the face. Clin. Anat. 24:162–167, 2011.

An anatomical study of the buccinator muscle fibres that extend to the terminal portion of the parotid duct, and their functional roles in salivary secretion

Until now there has been no definitive anatomical study describing the area where the parotid duct enters the buccinator muscle. In this study, we performed anatomical and histological examinations to investigate the relationship between the parotid duct and the buccinator muscle. Thirty specimens (including the buccinator and the terminal portion of the parotid duct) were obtained from embalmed Korean cadavers. Dissection was performed on 22 of these specimens, and the remaining eight specimens were prepared for histological examination and stained with haematoxylin–eosin or Gomori trichrome. In all specimens, small, distinct muscle fibres originating from the buccinator muscle extended to and inserted into the terminal portion of the parotid duct. The topography of these fibres varied, and we classified them into three categories according to where they originated. Type I buccinator muscle fibres, which inserted into the terminal portion of the parotid duct, originated simultaneously from the anterior and posterior aspects of the duct (ten cases, 45.5%). Type II fibres originated from the anterior aspect of the duct and inserted into the anterior side of the duct (seven cases, 31.8%). Type III fibres originated from the posterior aspect of the parotid duct and ran anteriorly toward the duct (five cases, 22.7%). These results were confirmed in the histological examination of all eight specimens. Based on these findings, we have proposed a tentative description of the physiological role of the buccinator muscle fibres in salivary secretion and in the formation of the sialoliths.

Medial muscular band of the orbicularis oculi muscle.

Abstract Despite the importance of anatomic variations in the muscular bands around the orbicularis oculi muscle (OOc), little is known about them. The morphology and variations therein of the medial muscular band of the OOc were thus examined in the current study. Sixty-one hemifaces of Korean cadavers were dissected to enable examination of the anatomic organization of the muscles around the OOc. A medial muscular band of the OOc was observed in 40 cases (65.6%). Three patterns of attachment were found. In type A (14 cases, 23%), it attached to the frontal belly without being attached to the medial canthal tendon; in type B (14 cases, 23%), it originated from the medial canthal tendon at the lower portion of the OOc and inserted into the cheek skin, and in type C (12 cases, 19.7%), it was also observed to insert into the cheek skin and attach to the frontal belly without being attached to the medial canthal tendon. The distance between the inferior edge of the OOc and the subnasale was 16.3 (SD, 4.3) mm and 14.5 (SD, 4.4) mm in cases with and without a medial muscular band, respectively. A space was observed on the inferolateral side of the OOc in about 67.2% of cases. These findings regarding the medial muscular band of the OOc increase further the anatomic variations associated with this region. In addition, it appears that this medial muscular band of the OOc can help to prevent drooping of the OOc.

Malaris muscle, the lateral muscular band of orbicularis oculi muscle.

Little is currently known about the variations in the muscular band around the orbicularis oculi muscle (OOc) region, and so the aim of the current study was to describe in anatomic terms the morphologic patterns of the lateral muscular bands of the OOc. Sixty-one hemifaces from embalmed Korean adult cadavers (34 males, 27 females; age range, 45-85 years; mean age, 62.6 years; 28 bilateral and 5 unilateral) were dissected to reveal the anatomic features of the region around the OOc. The lateral muscular band originating from the superficial temporal fascia lateral to the OOc was observed in 54.1% of cases. It terminated at the zygomatic arch region in 17 cases (type A, 27.9%), at the cheek region in 11 cases (type B, 18%), and at the angle of the mouth in 5 cases (type C, 8.2%). When the linear length from the lateral canthus to the tragion was set as 100, the length from the lateral canthus to the lateral edge of OOc was 34.0 (male, 34.1; female, 33.7), and the length between the lateral edge of OOc and the lateral muscular bands of OOc was 6.4 (male, 6.5; female, 6.2). The results of this study suggest that the lateral muscular bands of the OOc may play a significant role in facial animation and dimple formation. In addition, these data provide an index of suggested regions to be injected in patients with periorbital rhytides.

Morphology of the zygomaticus minor and its relationship with the orbicularis oculi muscle.

AbstractThe aim of this study was to examine in detail the anatomic variations in the orbicularis oculi muscle (OOc) and relationship of the zygomaticus minor muscle (ZMi) with the OOc, thereby providing an anatomic basis for explaining facial animation and attachment to the periorbital muscle. Sixty-one hemifaces from embalmed Korean adult cadavers (34 males, 27 females; age range, 45–85 years; mean age, 62.6 years) were used in this study. The prevalence of cases in which the ZMi did not run straight from the upper lip, rather running straight to the corner of the levator labii superioris, was 36.1% (22/61), because the origin of ZMi covered the inferior border of the OOc. The prevalence of mixing of the belly of the orbital part of the outer edge of the OOc with the ZMi was 88.5%, and that of blending of the ZMi band into the lower inner corner of the OOc was 55.7%. The area of blending of the OOc and ZMi was located 17.8 mm down from the Frankfort plane and 8.9 mm lateral to the vertical line between the lateral canthus and the Frankfort plane in the lateral part of the OOc. At this position, the mixed belly extends medially for a distance of 16 mm. This research has identified the exact location where the ZMi and OOc blend and determined the relationship between the ZMi and the suborbicularis oculi fat. This result will be given as basic data for understanding facial expressions and for performing composite rhytidectomy.