Increased miR-200c levels disrupt palatal fusion by affecting apoptosis, cell proliferation, and cell migration.

The mammalian palate separates the oral and nasal cavities, facilitating proper feeding, respiration, and speech. Palatal shelves, composed of neural crest-derived mesenchyme and surrounding epithelium, are a pair of maxillary prominences contributing to this structure. Palatogenesis reaches completion upon the fusion of the midline epithelial seam (MES) following contact between medial edge epithelium (MEE) cells in the palatal shelves. This process entails numerous cellular and molecular occurrences, including apoptosis, cell proliferation, cell migration, and epithelial-mesenchymal transition (EMT). MicroRNAs (miRs) are small, endogenous, non-coding RNAs derived from double-stranded hairpin precursors that regulate gene expression by binding to target mRNA sequences. Although miR-200c is a positive regulator of E-cadherin, its role in palatogenesis remains unclear. This study aims to explore the role of miR-200c in palate development. Before contact with palatal shelves, mir-200c was expressed in the MEE along with E-cadherin. After palatal shelf contact, miR-200c was present in the palatal epithelial lining and epithelial islands surrounding the fusion region but absent in the mesenchyme. The function of miR-200c was investigated by utilizing a lentiviral vector to facilitate overexpression. Ectopic expression of miR-200c resulted in E-cadherin upregulation, impaired dissolution of the MES, and reduced cell migration for palatal fusion. The findings imply that miR-200c is essential in palatal fusion as it governs E-cadherin expression, cell death, and cell migration, acting as a non-coding RNA. This study may contribute to clarifying the underlying molecular mechanisms in palate formation and provides insights into potential gene therapies for cleft palate.

Morphologic variations of the superior intercostal vein: An anatomical study with clinical applications.

This study aimed to validate and compare the anatomical variations of the superior intercostal veins, focusing on their origin, course, anastomoses, and destination. In addition, the results were compared with findings from other relevant studies. Fifty Korean and 16 Chinese adult cadavers were dissected for this study. The superior intercostal veins were dissected and measured. In our study of 66 specimens, the right superior intercostal vein was observed in 92.3% of cases, while the left superior intercostal vein was observed in 50%. The right superior intercostal vein was subdivided into six types based on its composition, which mainly drained the second and third right posterior intercostal veins. Similarly, the left superior intercostal vein was subdivided into eight types, primarily involving the second to fourth left posterior intercostal veins. This detailed anatomical study successfully identified and classified the various morphologic types of the superior intercostal vein and reviewed the clinical significance of this vein. The findings of this study can offer valuable anatomical evidence to physicians, aiding in their understanding and utilization of the superior intercostal vein.

Supraclavicular cephalic vein draining into the internal jugular vein via the external jugular vein.

PURPOSE: The aim of this study is to report rare anatomical variations of the cephalic vein (CV) in a 77-year-old Korean male cadaver. CASE REPORT: On the right upper arm, the CV located lateral to the deltopectoral groove passed anterior to the clavicle at the lateral one-fourth of the clavicle without anastomosis to the axillary vein. It was connected to the transverse cervical and suprascapular veins by two communicating branches in the middle of its course at the neck, and opened into the external jugular vein at its junction with the internal jugular veins. The suprascapular and anterior jugular veins were flowed into the subclavian vein at the jugulo-subclavian venous confluence, and were connected by a short communicating branch. CONCLUSION: Detailed knowledge of the variations in the CV is expected to be helpful in decreasing unpredicted injuries and possible postoperative complications when invasive venous access is performed through the CV.

An Unexpected Complication Resulting from Radiofrequency Ablation for Treating Facet Joint Syndrome: A Case Report.

Lumbar facet joints have been identified as a potential source of chronic low back pain (LBP) in 15% to 45% of patients, with the prevalence of such pain varying based on specific populations and settings examined. Lumbar facet joint interventions are useful in the diagnosis as well as the therapeutic management of chronic LBP. Radiofrequency ablation (RFA) of medial branch nerves is recognized as a safe and effective therapy for chronic facet joint pain in the lumbosacral spine, and its efficacy has already been established. The use of RFA is currently widespread in the management of spinal pain, but it is noteworthy that there have been works in the literature reporting complications, albeit at a very low frequency. We present a case of third-degree skin burns following radiofrequency ablation (RFA) for the management of facet joint syndrome. Postoperatively, the patient's skin encircling the needle displayed a pallor and exhibited deterioration in conjunction with the anatomical anomaly. The affected area required approximately 5 months to heal completely. During RFA, heat can induce burns not only at the point of contact with the RF electrode but also along the length of the needle. Vigilant attention is necessary to ensure patient safety and to address any potential complications that may arise during the procedure, including the possibility of minor technical errors.

Distribution patterns of the cutaneous nerves on the dorsum of the foot and their clinical significance.

The aim of this study was to clarify the distribution patterns of the cutaneous nerves on the dorsum of the foot. This study investigated 130 feet of 77 cadavers. The distribution patterns of the sural (SN) and deep fibular nerves (DFN) were classified into five and four types, respectively. In Type A, the SN was only distributed to the lateral side of the fifth toe. In Type B, the nerve was distributed to the medial side of the fourth toe and both sides of the fifth toe. In Type C, the nerve was mainly distributed to the lateral side of the fifth toe. In Type D, the nerve was distributed to the lateral side of the third toe and both sides of the fourth and fifth toes. In Type E, no SN was found. In Type α, the DFN was simultaneously distributed to the lateral side of the first toe and the medial side of the second toe. In Type ß, the nerve was distributed like in Type α and additionally to the medial side of the first toe. In Type γ, the nerve was distributed like in Type α and additionally to the lateral side of the second toe and the medial side of the third toe. In Type δ, no DFN was found. The results of this study will help physicians to reduce the incidence of iatrogenic nerve injury and improve the quality of diagnoses of relevant nerves in this body region. Clin. Anat. 33:592-597, 2020. © 2019 Wiley Periodicals, Inc.

Topographical study of the connections of the rami communicantes from the first to the fifth thoracic sympathetic ganglia.

This study investigated the morphological variations and histological patterns of the rami communicantes (RCs) arising from the first to the fifth thoracic sympathetic ganglia, and considered the clinical significance of these variations. Fifty upper thoracic portions from 26 adult Korean cadavers were used in this study. There were 731 RCs arising from the first to the fifth thoracic sympathetic ganglia. They were classified into three types depending on the connection between the sympathetic ganglion and the intercostal nerves: in type I, the RCs connected the ganglion to the corresponding intercostal nerve, and in types II and III, respectively, they connected it to the nerve one level above or below the corresponding intercostal nerve. Some RCs of types I and II could not be observed without additional preliminary surgical procedures. Diverse combinations of RC types arose from the first to the fifth thoracic sympathetic ganglia, combinations of types I and III being the most common (70%) in the first sympathetic ganglion and those comprising only type I being most frequent in the other ganglia. The RCs could not be identified by the naked eye in either fresh or fixed cadavers, so they were confirmed on the basis of their histological appearance. These results are expected to improve knowledge of morphological variations of the RCs in the upper five thoracic sympathetic ganglia, and to provide helpful information for clinical management in this region. Clin. Anat. 31:1151-1157, 2018. © 2018 Wiley Periodicals, Inc.

Topographical relationships between the obturator nerve, artery, and vein in the lateral pelvic wall.

INTRODUCTION AND HYPOTHESIS: The aims of this study were to determine the topographical relationships between the obturator nerve (ON), artery (OA), and vein (OV) in the lateral pelvic wall. METHODS: One hundred and fifty hemipelvises of 84 Korean cadavers were dissected. RESULTS: The ON, OA, and OV ran in that order (from upper to lower) within the lateral pelvic wall in 46.7 % of specimens. In 32 % of cases, the three structures were separated at the posterior portion of the wall and then converged toward the obturator canal (OC). In 10 %, the OA and OV were in contact with each other and separate from the ON; in 2 %, the ON was contiguous with the OA and separate from the OV; in 2.7 %, all three structures were in contact with each another. Alternately, the order of ON, OA, and OV was altered in the lateral pelvic wall in 41.3 % of specimens. Finally, in 12 % specimens, either the OA or OV or both were absent from the lateral pelvic wall. CONCLUSIONS: The possibility of the presence of either the OA or OV being between the ON and the external iliac vein, and the potential contact between the ON and either the OA or OV in the lateral pelvic wall, should be borne in mind during pelvic procedures.

Morphological Patterns and Variations of the Nasal Septum Components and Their Clinical Implications.

The aim of this study was to clarify the morphological patterns and proportions of the components of the nasal septum. Anatomical examinations were performed on 70 nasal septums of embalmed Korean adult cadavers. The septal deviation was checked before cutting the nasal cavity midsagittally with the aid of a laryngoscope. The shape of each component of the nasal septum was identified, and photographs were taken from a midline sagittal view. A line was drawn on each photograph between the septal components, and then the area of each septal component was measured using software. The mean area proportions of the septal cartilage (SC), the perpendicular plate of the ethmoid bone (PPE), the vomer, and the nasal crest of the maxilla relative to the total area of the nasal septum were 25.6%, 43.0%, 25.8%, and 5.6%, respectively. The morphology of the nasal septum was classified into 3 main patterns according to the proportion of each septal component. The proportions of the SC, the PPE, the vomer, and the nasal crest of the maxilla were similar to the mean values of the present study in 45.7%. The proportions of the SC, the PPE, and the vomer were similar to each other (with a difference of <15%) in 24.3%. The proportion of the PPE exceeded 50% of the total area of the nasal septum in 22.9%. The results reported herein provide detailed anatomical knowledge that can be used as a valuable reference for rhinoplasty procedures.

Morphological variations of the deltoid ligament of the medial ankle.

Morphological variations of the deltoid ligament were investigated in this study, with the aim of classifying the different types on the basis of their components. Sixty ankles from 39 cadavers were dissected. The origin and insertion sites of the deltoid ligament were identified, and its length, width, and thickness were measured. The deltoid ligament was divided into two layers, superficial and deep, which respectively comprised four components (tibionavicular, tibiospring, tibiocalcaneal, and superficial posterior tibiotalar ligaments) and two components (anterior tibiotalar and deep posterior tibiotalar ligaments). The tibiospring and tibiocalcaneal ligaments were found in 100% of the specimens, while the prevalence rates of other components lay within the range 63.3-96.7%. The tibionavicular and deep posterior tibiotalar ligaments were the thinnest and thickest, respectively, while the other ligaments had similar thicknesses. The deltoid ligament was classified into types I-IV according to the combinations of these components: all components were present in type I (48.3%), the tibionavicular ligament was absent in type II (36.7%), only the superficial posterior tibiotalar ligament was absent in type III (6.7%), and only the anterior tibiotalar ligament was absent in type IV (8.3%). In conclusion, these results improve knowledge of the morphological and morphometric characteristics of the deltoid ligament and thus provide helpful information for surgical procedures in this region. Clin. Anat. 29:1059-1065, 2016. © 2016 Wiley Periodicals, Inc.

Intermuscular aponeuroses between the flexor muscles of the forearm and their relationships with the ulnar nerve.

INTRODUCTION: The aim of this study was to clarify the morphological characteristics of the intermuscular aponeurosis between the flexor carpi ulnaris (FCU) and flexor digitorum superficialis (FDS; IMAS), and that between the FCU and flexor digitorum profundus (FDP; IMAP), and their topographic relationships with the ulnar nerve. MATERIALS AND METHODS: Fifty limbs of 38 adult cadavers were studied. RESULTS: The IMAS extended along the deep surface of the FCU adjoining the FDS, having the appearance of a ladder, giving off "steps" that decreased in width from superficial to deep around the middle of the forearm. Its proximal part divided into two bands connected by a thin membrane, and was attached to the medial epicondyle and the tubercle (the most medial prominent part of the coronoid process of the ulna), respectively. The IMAP extended deep between the FCU and FDP from the antebrachial fascia, and its distal end was located on the posterior border of the FCU. The IMAP became broader toward its proximal part, and its proximal end was attached anterior and posterior to the tubercle and the olecranon, respectively. The ulnar nerve passed posterior to the medial epicondyle and then medial to the tubercle, and was crossed by the deep border of the IMAS at 58.3 ± 14.1 mm below the medial epicondyle. CONCLUSION: The deep border of the IMAS and aberrant tendinous structure passing across the ulnar nerve, or the parts of the IMAS and IMAP passing posterior to the ulnar nerve are potential causes of ulnar nerve compression.

The enigmatic subcostal muscle: Anatomical study with application to spine and chest pain syndromes and avoidance of confusion on imaging.

The aim of this study was to revisit the morphological characteristics of the subcostal muscle and to obtain its morphometric data. One hundred and two sides of the thorax from 51 adult cadavers were used. The total number of subcostal muscles in the 102 specimens was 559. The subcostal muscle commonly comprised an aponeurosis at its superior and inferior attachments. This muscle had a thin band-like shape in 64.2% cases, while in the other 35.8% either its superior or inferior attachment was wider. It was classified into the following four types on the basis of its inferior attachment: in Types I and II it extended to two (79.3%) and three (12.0%) lower ribs, respectively; in Type III it joined adjacent muscles such as the psoas major (2.2%) or quadratus lumborum (0.7%); and in Type IV it was attached to the transverse process (0.4%) or body (3.9%) of the 12th thoracic vertebra and the body of the 1st lumbar vertebra (1.4%). The subcostal muscle was found at the deepest layer of the intercostal space, and mainly presented in the upper and lower parts of the thorax. Its width and height were 18.2 ± 10.9 mm (mean ± SD) and 56.0 ± 13.3 mm, respectively. The distances from the midsagittal line to the superior and inferior attachments of the subcostal muscle were 77.1 ± 13.0 mm and 48.9 ± 13.5 mm, respectively. The results of this study will help to advance current understanding of the subcostal muscle.

Zuckerkandl's tubercle of the thyroid gland: Its location in the anatomical position, and comparative morphology of the same specimens before and after fixation.

The aim of this study was to elucidate the definition of the borders and surface of the thyroid lobe in the anatomical position, and to compare the morphology of Zuckerkandl's tubercle (ZT) in the fresh and fixed states. One hundred thyroid lobes from 50 fresh Korean cadavers were used. The lateral border of the thyroid lobe could be defined as the most lateral margin of its anterior aspect when in the anatomical position. The posteromedial border was the margin that projected toward the trachea or tracheoesophageal groove. The lateral and posteromedial borders, and the posterior surface between these borders, could be identified in most of the fixed cadavers. The posterolateral border could only be identified in the thyroid lobe if there was compression by the internal carotid artery in cross-sectioned specimens and CT images. The ZT was identifiable in 85% of both fresh and fixed specimens. It was identified mainly at the posteromedial border of the thyroid lobe when in the anatomical position, and extended to the tracheoesophageal groove or esophagus. In the fresh state, the ZT projected as a rounded cone with a usually semicircular base, but its shape was very variable in the fixed state. In the present study, the ZT was found at the posteromedial border or posterior surface of the thyroid lobe in both the fresh and fixed states, contrary to most previous reports. The location of the ZT should be established in the anatomical position to avoid confusion.

A new morphological classification for the fibularis quartus muscle.

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.

Variable composition of the internal and external branches of the accessory nerve.

The purpose of this study was to clarify the composition of the internal and external branches (IB and EB) of the accessory nerve. Fifty-seven half heads of 34 adult cadavers were used. The IB and EB of the accessory nerve were mixed with the cranial root (CR), vagus nerve, and spinal root (SR). The IB was classified into five types and the EB into four types according to their composition. The IB consisted of only CR in 7.0% of the 57 cases, and of the CR and the vagus nerve in 52.6%; the IB did not exist in 12.3%. The EB was only composed of the SR in 19.3% of cases, the SR and CR in 52.6%, and the SR, CR, and the vagus nerve in 21.1%. There were 14 combinations of IB and EB types. The most common combination was the IB with the CR and the vagus nerve, and the EB with the SR and CR (31.6%). The combination of IB and EB comprising CR and SR, respectively, was not observed. The IB and EB are known to consist of the CR and SR of the accessory nerve, respectively. However, this study shows that there are no IB and EB comprising only the CR and SR, respectively, and the branches have various combinations of the CR, SR, and vagus nerve.

Morphological characteristics of the cranial root of the accessory nerve.

There has been the controversy surrounding the cranial root (CR) of the accessory nerve. This study was performed to clarify the morphological characteristics of the CR in the cranial cavity. Fifty sides of 25 adult cadaver heads were used. The accessory nerve was easily distinguished from the vagus nerve by the dura mater in the jugular foramen in 80% of 50 specimens. The trunk of the accessory nerve from the spinal cord penetrated the dura mater at various distances before entering the jugular foramen. In 20% of the specimens there was no dural boundary. In these cases, the uppermost cranial rootlet of the accessory nerve could be identified by removing the dura mater around the jugular foramen where it joined to the trunk of the accessory nerve at the superior vagal ganglion. The cranial rootlet was formed by union of two to four short filaments emerging from the medulla oblongata (66%) and emerged single, without filament (34%), and usually joined the trunk of the accessory nerve directly before the jugular foramen. The mean number of rootlets of the CR was 4.9 (range 2-9) above the cervicomedullary junction. The CR of the accessory nerve was composed of two to nine rootlets, which were formed by the union of two to four short filaments and joined the spinal root of the accessory nerve. The CR is morphologically distinct from the vagus nerve, confirming its existence.

Classification system for flexor digitorum accessorius longus muscle variants within the leg: clinical correlations.

The flexor digitorum accessorius longus (FDAL), a variant leg muscle, can cause tarsal tunnel syndrome. This study was performed to classify the variants of the FDAL by dissection and to correlate the dissection results with clinical cases of tarsal tunnel syndrome caused by this muscle. Eighty lower limbs of embalmed Korean cadavers were dissected. MR images of two clinical cases of tarsal tunnel syndrome caused by the FDAL were correlated with the dissection results. The FDAL was observed in nine out of 80 specimens (11.3%) and it was classified into three types depending on its site of origin and its relationship to the posterior tibial neurovascular bundle (PTNV) in the leg. In Type I (6.3%), the FDAL originated in the leg and ran superficially along the PTNV, either not crossing (Type Ia, 3.8%) or crossing (Type Ib, 2.5%) the neurovascular bundle. In Type II (6.3%), it originated in the tarsal tunnel. Most FDALs followed a similar course in the tarsal tunnel and the plantar pedis. On correlating the MR images of the clinical cases with this classification, the FDAL corresponded to Types Ia and II. All three types of FDAL can compress the tibial nerve in the tarsal tunnel or the distal leg. Clarification of the topographical relationship between this muscle and the PTNV would help to improve the results of surgery for tarsal tunnel syndrome caused by the FDAL.

Morphological study of the inferior transverse scapular ligament.

The suprascapular nerve can be compressed by the inferior transverse scapular ligament (ITSL), also known as the spinoglenoid ligament, and this entrapment results in dysfunction of the external rotation of the upper arm owing to isolated weakness of the infraspinatus muscle. The morphology of the ITSL has not been adequately characterized. The aim of this study was to clarify the morphological characteristics of the ITSL. In total, 110 shoulders from 72 cadavers were dissected in this study. The ITSL was present in 73 (66.4%) of the 110 specimens, and comprised membrane in 40 (36.4%), ligament in 25 (22.7%), and both membrane and ligament in eight (7.3%). This structure could be classified into three types on the basis of its shape: band-like (33.6%, type I), triangular (15.5%, type II), or irregular (17.3%, type III). In the spinoglenoid notch, the suprascapular nerve was always close to the lateral margin of the scapular spine. The length of the ligament between its origin and insertion sites ranged from 8.7 to 23.4 mm at its superior margin and from 8.9 to 17.5 mm at its inferior margin. The ligament width and thickness at its midportion ranged from 1.6 to 10.0 mm and from 0.1 to 1.2 mm, respectively. The results of this study improve understanding of the ITSL and will be helpful for successful diagnoses and treatments for selective suprascapular nerve entrapment.

Posterior tibiotalar ligament: an anatomic study correlated with MRI.

This study was performed to clarify the morphologic characteristics of two layers of the posterior tibiotalar ligament (PTT) and two bands of the deep PTT (dPTT), and to correlate the dissection findings with MR images. Sixty-four ankles from 42 cadavers were examined. The origin and insertion sites of the superficial PTT (sPTT) and the two bands of the dPTT were identified, and their length, width, and thickness were measured. MRI was performed on four ankles before serial sectioning or dissection. The serial sections were taken at a thickness of 2 mm. The sPTT was observed in 50 out of 60 dissected specimens (83.3%), taken from 64 ankles of 42 cadavers. The dPTT was observed in all specimens. The sPTT, superficial band of the dPTT (sdPTT), and deep band of the dPTT (ddPTT) arose from the inferior surface of the medial malleolus. The sPTT attached to the posterior process of the talus, and the sdPTT and ddPTT attached to the depression below the articular facet for the medial malleolus. The sPTT and two bands of the dPTT could be distinguished on coronal MR images, where the sPTT appeared as a thin string superficial to the two bands of the dPTT, which were separated as two thick, low-density strings. In the coronal plane of frozen sections, the outermost sPTT appeared as a thin, white bundle attached to the sdPTT. The PTT is composed of superficial and deep layers, and the dPTT is composed of superficial and deep bands.

Comparison of international medical costs for interventional pain treatment: a focus on Korea and Japan.

Background: The rise in national health care costs has emerged as a global problem given the ever-aging population and rapid development of medical technology. The utilization of interventional pain management has, similarly, shown a continued rise worldwide. This study evaluates the differences in the medical costs in the field of interventional pain treatment (IPT) between two countries: Korea and Japan. Methods: Korean medical insurance costs for 2019 related to pain management focused on IPT were compared to those of Japan. Purchasing power parity (PPP) was used to adjust the exchange rate differences and to compare prices in consideration of the respective societies' economic power. Results: The cost of trigger point injections in Japan was 1.06 times higher than that of Korea, whereas the perineural and intraarticular injection prices were lower in Japan. The cost of epidural blocks was higher in Japan compared to Korea in both cervical/thoracic and lumbar regions. As for blocks of peripheral branches of spinal nerves, the cost of scapular nerve blocks in Japan was lower than that in Korea, given a PPP ratio 0.09. For nerve blocks in which fluoroscopy guidance is mandatory, the costs of epidurography in Japan were greater than those in Korea, given a PPP ratio 1.04. Conclusions: This is the first comparative study focusing on the medical costs related to IPT between Korea and Japan, which reveals that the costs differed along various categories. Further comparisons reflecting more diverse countries and socio-economic aspects will be required.

New insight into the vasto-adductor membrane for safer adductor canal blockade.

Background: : This study aimed to identify exact anatomical landmarks and ideal injection volumes for safe adductor canal blocks (ACB). Methods: : Fifty thighs from 25 embalmed adult Korean cadavers were used. The measurement baseline was the line connecting the anterior superior iliac spine (ASIS) to the midpoint of the patellar base. All target points were measured perpendicular to the baseline. The relevant cadaveric structures were observed using ultrasound (US) and confirmed in living individuals. US-guided dye injection was performed to determine the ideal volume. Results: : The apex of the femoral triangle was 25.3 ± 2.2 cm distal to the ASIS on the baseline and 5.3 ± 1.0 cm perpendicular to that point. The midpoint of the superior border of the vasto-adductor membrane (VAM) was 27.4 ± 2.0 cm distal to the ASIS on the baseline and 5.0 ± 1.1 cm perpendicular to that point. The VAM had a trapezoidal shape and was connected as an aponeurosis between the medial edge of the vastus medialis muscle and lateral edge of the adductor magnus muscle. The nerve to the vastus medialis penetrated the muscle proximal to the superior border of the VAM in 70% of specimens. The VAM appeared on US as a hyperechoic area connecting the vastus medialis and adductor magnus muscles between the sartorius muscle and femoral artery. Conclusions: : Confirming the crucial landmark, the VAM, is beneficial when performing ACB. It is advisable to insert the needle obliquely below the superior VAM border, and a 5 mL injection is considered sufficient.