A Brief Review of Anatomy Education in Korea, Encompassing Its Past, Present, and Future Direction.

Anatomy is a foundational subject in medicine and serves as its language. Hippocrates highlighted its importance, while Herophilus pioneered human dissection, earning him the title of the founder of anatomy. Vesalius later established modern anatomy, which has since evolved historically. In Korea, formal anatomy education for medical training began with the introduction of Western medicine during the late Joseon Dynasty. Before and after the Japanese occupation, anatomy education was conducted in the German style, and after liberation, it was maintained and developed by a small number of domestic anatomists. Medicine in Korea has grown alongside the country's rapid economic and social development. Today, 40 medical colleges produce world-class doctors to provide the best medical care service in the country. However, the societal demand for more doctors is growing in order to proactively address to challenges such as public healthcare issues, essential healthcare provision, regional medical service disparities, and an aging population. This study examines the history, current state, and challenges of anatomy education in Korea, emphasizing the availability of medical educators, support staff, and cadavers for gross anatomy instruction. While variations exist between Seoul and provincial medical colleges, each manages to deliver adequate education under challenging conditions. However, the rapid increase in medical student enrollment threatens to strain existing anatomy education resources, potentially compromising educational quality. To address these concerns, we propose strategies for training qualified gross anatomy educators, ensuring a sustainable cadaver supply, and enhancing infrastructure.

Investigation of Optimal Needle Position for Radiofrequency Ablation-Based Blockade of Interspace between the Popliteal Artery and the Posterior Capsule of the Knee: A Cadaveric Study.

Background and Objectives: The interspace between the popliteal artery and the posterior capsule of the knee (iPACK) block has been widely used in perioperative settings to control posterior knee pain and can additionally be used for chronic knee pain. In this cadaveric study, we aimed to investigate the needle tip position and its proximity to the articular branch of the tibial nerve (ABTN) during an iPACK-targeted radiofrequency procedure. Materials and Methods: An ultrasound-guided iPACK block was performed on 20 knees of 10 cadavers. We injected 0.1 mL each of blue and green gelatinous dye near the tibial artery (point A) and posterior knee capsule (point B), respectively, and evaluated the spread of both around the ABTN. For a hypothetical conventional radiofrequency ablation (RFA) lesion (diameter, 2.95 mm) and cooled RFA lesion (diameter, 4.9 mm), we counted the number of specimens in which the ABTNs would be captured. Results: The percentage of specimens in which the ABTN would be captured by a cooled RFA lesion was 64.71% at point A and 43.75% at point B (p = 0.334). Meanwhile, the percentage of specimens in which the ABTN would be captured by a conventional RFA lesion was 58.82% from point A and 25% from point B (p = 0.065). Conclusions: When performing an RFA-based iPACK block, the needle tip may be positioned either lateral to the tibial artery or in the space between the posterior knee capsule and the tibial artery. However, more studies with larger samples are needed to verify these results before the clinical use of this procedure can be recommended.

Optimal needle electromyography approach to the serratus anterior muscle.

INTRODUCTION/AIMS: There are two conventional needle electromyography (EMG) approaches to the serratus anterior (SA), both of which can result in erroneous insertion into adjacent structures such as the latissimus dorsi (LD), teres major, or external oblique abdominis muscles and pose a risk of long thoracic nerve (LTN) injury. Therefore, we identified a novel needle insertion point for the SA in cadavers that avoids other muscles and LTN injury. METHODS: This study included 17 cadavers: 12 to devise the new method and 5 to verify its accuracy. Novel landmarks were the inferior angle of the scapula (I), sternal notch (S), and xiphoid process (X). The relationships of the LD, pectoralis major (PM), SA, and LTN were determined relative to these landmarks. RESULTS: When inserting a needle into the proximal one third along the line connecting points I and X, there were adequate safety margins around the LD, PM, and LTN, and the new method had excellent accuracy. DISCUSSION: Compared to the conventional midaxillary method, our novel method improved the accuracy of needle EMG of the SA. Follow-up studies using clinical imaging techniques are needed to verify whether above findings are equally applicable in living subjects.

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.

A Distinct Microglial Cell Population Expressing Both CD86 and CD206 Constitutes a Dominant Type and Executes Phagocytosis in Two Mouse Models of Retinal Degeneration.

Microglial cells are the key regulators of inflammation during retinal degeneration (RD) and are conventionally classified as M1 or M2. However, whether the M1/M2 classification exactly reflects the functional classification of microglial cells in the retina remains debatable. We examined the spatiotemporal changes of microglial cells in the blue-LED and NaIO3-induced RD mice models using M1/M2 markers and functional genes. TUNEL assay was performed to detect photoreceptor cell death, and microglial cells were labeled with anti-IBA1, P2RY12, CD86, and CD206 antibodies. FACS was used to isolate microglial cells with anti-CD206 and CD86 antibodies, and qRT-PCR was performed to evaluate Il-10, Il-6, Trem-2, Apoe, and Lyz2 expression. TUNEL-positive cells were detected in the outer nuclear layer (ONL) from 24 h to 72 h post-RD induction. At 24 h, P2RY12 was decreased and CD86 was increased, and CD86/CD206 double-labeled cells occupied the dominant population at 72 h. And CD86/CD206 double-labeled cells showed a significant increase in Apoe, Trem2, and Lyz2 levels but not in those of Il-6 and Il-10. Our results demonstrate that microglial cells in active RD cannot be classified as M1 or M2, and the majority of microglia express both CD86 and CD206, which are involved in phagocytosis rather than inflammation.

Intravitreal Administration of Retinal Organoids-Derived Exosomes Alleviates Photoreceptor Degeneration in Royal College of Surgeons Rats by Targeting the Mitogen-Activated Protein Kinase Pathway.

Increasing evidence suggests that exosomes are involved in retinal cell degeneration, including their insufficient release; hence, they have become important indicators of retinopathies. The exosomal microRNA (miRNA), in particular, play important roles in regulating ocular and retinal cell functions, including photoreceptor maturation, maintenance, and visual function. Here, we generated retinal organoids (ROs) from human induced pluripotent stem cells that differentiated in a conditioned medium for 60 days, after which exosomes were extracted from ROs (Exo-ROs). Subsequently, we intravitreally injected the Exo-RO solution into the eyes of the Royal College of Surgeons (RCS) rats. Intravitreal Exo-RO administration reduced photoreceptor apoptosis, prevented outer nuclear layer thinning, and preserved visual function in RCS rats. RNA sequencing and miRNA profiling showed that exosomal miRNAs are mainly involved in the mitogen-activated protein kinase (MAPK) signaling pathway. In addition, the expression of MAPK-related genes and proteins was significantly decreased in the Exo-RO-treated group. These results suggest that Exo-ROs may be a potentially novel strategy for delaying retinal degeneration by targeting the MAPK signaling pathway.

Single-stranded RNA adjuvant enhances the efficacy of 10-valent human papilloma virus-like particle vaccine.

Following the development of various types of vaccines, the use of adjuvants to boost vaccine efficacy has become a focus of research. Aluminum hydroxide (alum), the most commonly used adjuvant, induces a certain immune response and ensures safety in human trials. However, alum mainly induces only a Th2 response; its Th1 response is weak. Thus, we previously developed a single-stranded ribose nucleic acid (ssRNA) adjuvant that induces a Th1 response through toll-like receptors. Here, we explored whether 10-valent human papilloma virus (HPV)-like particle (VLP) vaccine formulated with ssRNA adjuvant and alum helped to enhance immune response and maintained memory response. The mice were immunized intramuscularly twice at 2 week intervals and were inoculated 4 days after the second boost (after about 1 year). The antibody response and T cell activation were measured by Elispot, ELISA using harvested serum and splenocytes. The 10-valent HPV VLP vaccine formulated with ssRNA adjuvant and alum increased the antigen-specific immune response more than alum used alone. It increased each type-specific IgG1/IgG2a titer, and antigen-specific IFN-γ cells. Furthermore, the ssRNA adjuvant with alum induced memory response. In memory response, each type-specific IgG1/IgG2c, IFN-γ, and IL-6 cytokine, and neutralizing antibodies were increased by the ssRNA adjuvant with alum. Overall, the ssRNA adjuvant with alum induced memory responses and balanced Th1/Th2 responses. The ssRNA adjuvant and alum may help to enhance prophylactic vaccine efficacy.

ANO1/TMEM16A regulates process maturation in radial glial cells in the developing brain.

Neural stem cells (NSCs) are primary progenitor cells in the early developmental stage in the brain that initiate a diverse lineage of differentiated neurons and glia. Radial glial cells (RGCs), a type of neural stem cell in the ventricular zone, are essential for nurturing and delivering new immature neurons to the appropriate cortical target layers. Here we report that Anoctamin 1 (ANO1)/TMEM16A, a Ca2+-activated chloride channel, mediates the Ca2+-dependent process extension of RGCs. ANO1 is highly expressed and functionally active in RGCs of the mouse embryonic ventricular zone. Knockdown of ANO1 suppresses RGC process extension and protrusions, whereas ANO1 overexpression stimulates process extension. Among various trophic factors, brain-derived neurotrophic factor (BDNF) activates ANO1, which is required for BDNF-induced process extension in RGCs. More importantly, Ano1-deficient mice exhibited disrupted cortical layers and reduced cortical thickness. We thus conclude that the regulation of RGC process extension by ANO1 contributes to the normal formation of mouse embryonic brain.

Correction: Kim et al. Correlative Light and Electron Microscopy Using Frozen Section Obtained Using Cryo-Ultramicrotomy. Int. J. Mol. Sci. 2021, 22, 4273.

The authors wish to make a correction to this paper [...].

Paradoxical paramagnetic calcifications in the globus pallidus: An ex vivo MR investigation and histological validation study.

MR images based on phase contrast images have gained clinical interest as an in vivo tool for assessing anatomical and histological findings. The globus pallidus is an area of major iron metabolism and storage in the brain tissue. Calcium, another important metal in the body, is frequently deposited in the globus pallidus as well. Recently, we observed dense paramagnetic deposition with paradoxical calcifications in the globus pallidus and putamen. In this work, we explore detailed MR findings on these structures, and the histological source of the related findings using ex vivo CT and MR images. Ex vivo MR was obtained with a maximum 100 µm3 isotropic resolution using a 15.2 T MR system. 3D gradient echo images and quantitative susceptibility mapping were used because of their good sensitivity to metallic deposition, high signal-to-noise ratio, and excellent contrast to iron and calcium. We found dense paramagnetic deposition along the perforating arteries in the globus pallidus. This paramagnetic deposition was hyperdense on ex vivo CT scans. Histological studies confirmed this finding, and simultaneous deposition of iron and calcium, although more iron dominant, was observed along the vessel walls of the globus pallidus. This was an exclusive finding for the penetrating arteries of the globus pallidus. Thus, our results suggest that several strong and paradoxical paramagnetic sources at the globus pallidus can be associated with vascular degeneration.

Complement System and Potential Therapeutics in Age-Related Macular Degeneration.

Age-related macular degeneration (AMD) is a complex multifactorial disease characterized in its late form by neovascularization (wet type) or geographic atrophy of the retinal pigment epithelium cell layer (dry type). The complement system is an intrinsic component of innate immunity. There has been growing evidence that the complement system plays an integral role in maintaining immune surveillance and homeostasis in AMD. Based on the association between the genotypes of complement variants and AMD occurrence and the presence of complement in drusen from AMD patients, the complement system has become a therapeutic target for AMD. However, the mechanism of complement disease propagation in AMD has not been fully understood. This concise review focuses on an overall understanding of the role of the complement system in AMD and its ongoing clinical trials. It provides further insights into a strategy for the treatment of AMD targeting the complement system.

Correlative Light and Electron Microscopy Using Frozen Section Obtained Using Cryo-Ultramicrotomy.

Immuno-electron microscopy (Immuno-EM) is a powerful tool for identifying molecular targets with ultrastructural details in biological specimens. However, technical barriers, such as the loss of ultrastructural integrity, the decrease in antigenicity, or artifacts in the handling process, hinder the widespread use of the technique by biomedical researchers. We developed a method to overcome such challenges by combining light and electron microscopy with immunolabeling based on Tokuyasu's method. Using cryo-sectioned biological specimens, target proteins with excellent antigenicity were first immunolabeled for confocal analysis, and then the same tissue sections were further processed for electron microscopy, which provided a well-preserved ultrastructure comparable to that obtained using conventional electron microscopy. Moreover, this method does not require specifically designed correlative light and electron microscopy (CLEM) devices but rather employs conventional confocal and electron microscopes; therefore, it can be easily applied in many biomedical studies.

Distribution of the Laterally Supplying Facial Nerve to the Orbicularis Oculi Muscle.

BACKGROUND: The facial nerve that traverses the lateral border of the orbicularis oculi muscle is considered the primary motor for the muscle. Nevertheless, the lateral motor supply to the orbicularis oculi muscle has not yet been fully described. OBJECTIVES: The aim of this study was to report detailed anatomic information about the lateral motor supply route to the orbicularis oculi. METHODS: Facial nerve branches that cross the lateral orbicularis oculi border were fully traced from the parotid border to the nerve destinations in 43 fresh hemifaces by microscopic surgical dissection and time-lapse photography. RESULTS: Through the lateral route, the anterior temporal and upper zygomatic branches supply the superior orbital and superior preseptal orbicularis oculi of the upper eyelid, as well as the lateral pretarsal and malar orbicularis oculi, excluding the upper medial pretarsal portion of the upper eyelid and most of the lower eyelid. The nerve supplying the lateral pretarsal orbicularis oculi muscle crosses the anterior area of the zygomatic arch. It then traverses an area 6 mm above and 4 mm below the lateral canthal crease. CONCLUSIONS: The anterior area of the zygomatic arch and an area 6 mm above and 4 mm below the lateral canthal crease are the facial nerve danger zones. The present anatomic findings provide surgeons with further insights for performing blepharoplasty, midface lift, facelift, and facial nerve reconstructive surgery.

Safety of Retrograde Flow of Internal Mammary Vein: Cadaveric Study and Anatomical Evidence.

BACKGROUND: Additional second vessels may be required to handle multiple flaps used to add breast volume, boost blood flow for supercharging, or use salvage recipient vessels. In these situations, retrograde internal mammary vessel flow can be used although this causes doubts and concerns. PATIENTS AND METHODS: Forty sides of the chests of 20 fresh cadavers with intact thoracic cages and internal mammary veins (IMV) were used in the study. IMV valve numbers and locations were checked, and the bifurcation was confirmed. A retrograde fluorescent angiography and a saline infusion test were followed to confirm flow direction. RESULTS: Twenty-eight vessels were identified in 40 sides of the chest; of them, 45% had no valves. A mean 0.7 valves per chest side were identified; 23 (82.1%) of 28 valves were located above the second intercostal space (ICS). A mean 1.76 communicating veins were found between the IMV bifurcation. In all cadavers, a crossing vein connecting the left and right medial IMV was confirmed just below the xiphoid process. Fluorescent angiography and a saline infusion test proved that the retrograde flow was caudal through the bifurcated IMV to the communicating, intercostal, and crossing veins. CONCLUSION: The IMV valve was present in 55% of our subjects and located concentrically above the second ICS level. It is highly unlikely that the retrograde flow was disturbed because the retrograde anastomosis level was below the second ICS. Furthermore, the bifurcation, intercostal, and crossing veins across the xiphoid process enabled valve-less detour flow. Thus, retrograde IMV flow is considered safe.

Detailed anatomy of the trochlear nerve in the superior oblique muscle.

PURPOSE: The purpose of this study was to elucidate the detailed anatomy of the trochlear nerve in the superior oblique muscle (SOM) and the intramuscular innervation pattern using Sihler staining. METHODS: SOMs were dissected from their origin to the insertion in 28 eyes of 14 cadavers. The following distances were determined: from the SOM insertion to the trochlear, from the trochlear to the entry site of the anterior branch or posterior branch, and the widths of the main trunk and anterior and posterior branches. Sihler staining was then performed. RESULTS: The trochlear nerve traveled straight ahead medially and divided. Eighteen of 28 (64.3%) orbits showed two anterior and posterior branches, six (21.4%) showed three branches, and four (14.3%) showed no branching. The most distally located intramuscular nerve ending was observed at 62.4 ± 2.4% of the length of each muscle (35.8 mm from insertion when considering that the length of the SOM was 57.4 mm) and at 29.9 ± 3.2% of the length of each muscle (17.2 mm from the trochlear). Additionally, the length of the intramuscular arborization part was 9.4 ± 1.1% of the length of the SOM (5.4 mm when considering that the length of the SOM was 57.4 mm). Nonoverlap between two intramuscular arborizations of the nerve was detected in 20 of 28 cases (71.4%). Eight cases (28.6%) showed a definite overlap of two zones. CONCLUSIONS: This study provided a good understanding of the anatomy of the trochlear nerve in the SOM.

Biallelic Deletion of Pxdn in Mice Leads to Anophthalmia and Severe Eye Malformation.

Peroxidasin (PXDN) is a unique peroxidase containing extracellular matrix motifs and stabilizes collagen IV networks by forming sulfilimine crosslinks. PXDN gene knockout in Caenorhabditis elegans (C. elegans) and Drosophila results in the demise at the embryonic and larval stages. PXDN mutations lead to severe eye disorders, including microphthalmia, cataract, glaucoma, and anterior segment dysgenesis in humans and mice. To investigate how PXDN loss of function affects organ development, we generated Pxdn knockout mice by deletion of exon 1 and its 5' upstream sequences of the Pxdn gene using the CRISPR/Cas9 system. Loss of both PXDN expression and collagen IV sulfilimine cross-links was detected only in the homozygous mice, which showed completely or almost closed eyelids with small eyes, having no apparent external morphological defects in other organs. In histological analysis of eye tissues, the homozygous mice had extreme defects in eye development, including no eyeballs or drastically disorganized eye structures, whereas the heterozygous mice showed normal eye structure. Visual function tests also revealed no obvious functional abnormalities in the eyes between heterozygous mice and wild-type mice. Thus, these results suggest that PXDN activity is essential in eye development, and also indicate that a single allele of Pxdn gene is sufficient for eye-structure formation and normal visual function.

Detailed Anatomy of Osteoperiosteal Ligamentous Structures in the Forehead.

This study aimed to present the anatomic characteristics of osteoperiosteal ligamentous attachments of the forehead and provide a better understanding of lateral eyebrow descent for safe and effective foreheadplasty. Anatomic dissections of the face were performed in 10 fresh Korean adult cadavers (20 hemifaces) using 2.5× magnification surgical loupes. Supraorbital, inferomedial orbital, and frontonasal osteoperiosteal ligamentous attachments were identified as fibrous tissues originating from a bone, and their tensile strengths were measured. The supraorbital osteoperiosteal ligamentous attachment had medial and lateral parts. It can be classified into 4 subtypes. It was located 11.0 ±â€Š6.6 mm lateral to the midline and 9.2 ±â€Š12.3 mm superior to the superior orbital margin. The inferomedial orbital osteoperiosteal ligamentous attachment was located 16.2 ±â€Š3.9 mm lateral to the midline and 2.2 ±â€Š2.7 mm inferior to the superior orbital margin, whereas the frontonasal osteoperiosteal ligamentous attachment was located 5.4 ±â€Š2.3 mm lateral to the midline and 1.4 ±â€Š8.5 mm superior to the superior orbital margin. Tensile strengths of all the osteoperiosteal ligamentous attachments in the forehead were above 10 N. These results indicate that osteoperiosteal ligamentous attachments develop in the rather medial region of the eyebrow and have a tensile strength adequate enough to maintain the medial eyebrow. Thus, the current study provides surgeons with detailed anatomic information that can be used as a valuable reference for forehead rejuvenation procedures.

The Use of a Retromammary Adipofascial Flap in Breast Augmentation for Patients with Thin Soft Tissue.

BACKGROUND: In patients with a thin soft tissue breast envelope, lower pole implant palpability is a postoperative sequela that concerns patients. Anatomically, the lower aspect of the breast near the inframammary fold lacks sufficient soft tissue to cover the breast implant after augmentation. METHODS: A transareolar incision was made, and subcutaneous dissection was performed. The dissection first proceeded caudally to the lower aspect to the breast parenchyma. The dissection then changed direction and moved cephalad to the mid breast or nipple region. The fatty tissue and pectoralis muscle fascia were cut transversely at this level, and the dissection was reversed caudally in a subfascial plane to the new inframammary fold region. This maneuver created a retromammary adipofascial flap. RESULTS: A total of 368 breast augmentations were performed in 184 patients. Breast implants were inserted in the subfascial plane in 40 patients (21.7%) and in the subpectoral-subfascial plane in 144 patients (78.3%). A total of 368 breast implants were inserted, including 140 smooth cohesive silicone implants (38.0%), 2 textured round implants (0.5%), and 226 anatomic-type implants (61.5%). A cadaveric dissection revealed that a retromammary adipofascial flap measuring 3-4 mm in thickness can be acquired. Capsular contracture occurred in six breasts (1.7%). CONCLUSIONS: During breast augmentation, an inferiorly based retromammary adipofascial flap can be created to help cover the lower pole of the breast from implant palpability. This is helpful especially in patients with thin skin, hypoplastic breasts, or constricted breasts. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Tricyclic antidepressant amitriptyline inhibits 5-hydroxytryptamine 3 receptor currents in NCB-20 cells.

Amitriptyline, a tricyclic antidepressant, is commonly used to treat depression and neuropathic pain, but its mechanism is still unclear. We tested the effect of amitriptyline on 5-hydroxytryptamine 3 (5-HT3) receptor currents and studied its blocking mechanism because the clinical applications of amitriptyline overlapped with 5-HT3 receptor therapeutic potentials. Using a whole-cell voltage clamp method, we recorded the currents of the 5-HT3 receptor when 5-HT was applied alone or co-applied with amitriptyline in cultured NCB-20 neuroblastoma cells known to express 5-HT3 receptors. To elucidate the mechanism of amitriptyline, we simulated the 5-HT3 receptor currents using Berkeley Madonna® software and calculated the rate constants of the agonist binding and receptor transition steps. The 5-HT3 receptor currents were inhibited by amitriptyline in a concentration-dependent, voltage-independent manner, and a competitive mode. Amitriptyline accelerated the desensitization of the 5-HT3 receptor. When amitriptyline was applied before 5-HT treatment, the currents rose slowly until the end of 5-HT treatment. When amitriptyline was co-applied with 5-HT, currents rose and decayed rapidly. Peak current amplitudes were decreased in both applications. All macroscopic currents recorded in whole cell voltage clamping experiments were reproduced by simulation and the changes of rate constants by amitriptyline were correlated with macroscopic current recording data. These results suggest that amitriptyline blocks the 5-HT3 receptor by close and open state blocking mechanisms, in a competitive manner. We could expand an understanding of pharmacological mechanisms of amitriptyline related to the modulation of a 5-HT3 receptor, a potential target of neurologic and psychiatric diseases through this study.

A perforator from the ulnar artery and cutaneous nerve of the hypothenar area: An anatomical study for clinical application.

PURPOSE: The hypothenar perforator flap is a recently introduced method for fingertip reconstruction, which offers excellent results but lacks adequate anatomic studies. The present study is aimed to clarify the anatomic characteristics of the hypothenar area to analyze the potential clinical application of sensate flaps and to access the reliability of hypothenar perforator arteries. MATERIALS AND METHODS: A total of 26 amputated forearms were used, and a percentage scattergram using an x-y-axis was created. The y-axis was a vertical line from the midpoint of pisiform base (0%) to the midvolar crease of the metacarpophalangeal joint (100%). The x-axis was a line perpendicular to the y-axis, and was quantified as a percentage value. We then studied the number of perforators, the diameter and length of the pedicle, and evaluated the differences between the zones and sexes. RESULTS: A reliable region for the hypothenar perforator flap, including more than two perforator arteries with an average diameter of over 1 mm, was mapped as 5%-20% on the x-axis and 10%-50% on the y-axis. The nerves appeared to occur more densely than the arteries, with 5%-15% on the x-axis and 25%-60% on the y-axis. CONCLUSION: The most consistent area for sensate flap elevation was the region around 5%-15% on the x-axis and 25%-50% on the y-axis. We expect that our data concerning perforator artery and cutaneous nerve branches in the hypothenar area of the hand will aid in establishing appropriate clinical usage of the hypothenar perforator flap. © 2014 Wiley Periodicals, Inc. Microsurgery 37:49-56, 2017.