Letter to the Editor on "Radiologic serosal invasion sign as a new criterion of T4a gastric cancer on computed tomography: diagnostic performance and prognostic significance in patients with advanced gastric cancer".

We provide commentary on the paper by You et al., which proposed the 'serosal invasion sign' as a new criterion for T4a gastric cancer on CT. We clarify the anatomical relationship between the perigastric vessels and the serosa, correcting for an anatomical oversight in the original figures. We affirm the significance of this diagnostic sign in the T-staging of gastric cancer. Our insights aim to enhance the understanding and clinical application of this criterion in staging advanced gastric cancer.

Prevalence and quantity of lymph nodes at mediastinal stations in patients with lung cancer: lessons from 181 bilateral mediastinal lymphadenectomies.

BACKGROUND: This study evaluated the prevalence and quantity of lymph nodes at particular stations of the mediastinum in patients with lung cancer. These data are important to radiologists, pathologists, and thoracic surgeons because they can serve as a benchmark when assessing the completeness of lymph node dissection. However, relevant data in the literature are scarce. METHODS: Data regarding the number of lymph nodes derived from two randomised trials of bilateral mediastinal lymph node dissection, the BML-1 and BML-2 study, were included in this analysis. Detectable nodes at particular stations of the mediastinum and the number of nodes at these stations were analysed. RESULTS: The mean number of removed nodes was 28.67 (range, 4-88). Detectable lymph nodes were present at stations 2R, 4R, and 7 in 93%, 98%, and 99% of patients, respectively. Nodes were rarely present at stations 9 L (33%), and 3 (35%). The largest number of nodes was observed at stations 7 and 4R (mean, 5 nodes). CONCLUSION: The number of mediastinal lymph nodes in patients with lung cancer may be greater than that in healthy individuals. Lymph nodes were observed at stations 2R, 4R, and 7 in more than 90% of patients with lung cancer. The largest number of nodes was observed at stations 4R and 7. Detectable nodes were rarely observed at stations 3 and 9 L. TRIAL REGISTRATION: ISRCTN 86,637,908.

Accuracy and repeatability of 3D Photogrammetry to digitally reconstruct bones.

Advances in computer hardware and software permit the reconstruction of physical objects digitally from digital camera images. Given the varying shapes and sizes of human bones, a comprehensive assessment is required to establish the accuracy of digital bone reconstructions from three-dimensional (3D) photogrammetry. Five human bones (femur, radius, scapula, vertebra, patella) were marked with pencil, to establish between 9 and 29 landmarks. The distances between landmarks were measured from the physical bones and digitized from 3D reconstructions. Images used for reconstructions were taken on two separate days, allowing for repeatability to be established. In comparison to physical measurements, the mean (±standard deviation) absolute differences were between 0.2±0.1mm and 0.4±0.2mm. The mean (±standard deviation) absolute differences between reconstructions were between 0.3±<0.1mm and 0.4±0.4mm. The 3D photogrammetry procedures described are accurate and repeatable, permitting quantitative analyses to be conducted from digital reconstructions. Moreover, 3D photogrammetry may be used to capture and preserve anatomical materials for anatomy education.

Compressive Neuropathies of the Upper Extremity: Anatomy for the Peripheral Nerve Surgeon.

Advance knowledge of anatomy is a prerequisite for the peripheral nerve surgeon. This article serves to provide an outline of anatomic regions where nerve entrapment or compression can occur. Each section is subdivided into anatomic regions where the etiology, indications, and relevant and aberrant anatomy are discussed, as well as common surgical approaches to the problematic anatomic site. The purpose is to provide an overview for the peripheral nerve surgeon and offer a valuable resource to provide a better understanding and optimal care for this patient population.

Endoscopic Endonasal Approach to the Ventral Petroclival Fissure: Anatomical Findings and Surgical Techniques.

Objective The endoscopic endonasal approach has emerged as an excellent option for the treatment of lesions involving the petroclival fissure (PCF). Here, we investigate the surgical anatomy of the ventral PCF and its application in endoscopic endonasal surgery. Methods Sixteen head specimens were used to investigate the anatomical features of PCF and relevant technical nuances in translacerum, extreme medial, and contralateral transmaxillary (CTM) approaches. Two representative endoscopic endonasal surgeries involving the PCF were selected to illustrate the clinical application. Results From the endoscopic endonasal view, the ventral PCF is presented as a lazy L sign, which is divided into two distinct segments: (1) upper (or petrosphenoidal) segment, which extends vertically from the foramen lacerum inferiorly to the junction of the petrosal process of sphenoid bone and petrous apex superiorly, and (2) lower (or petroclival) segment, which extends inferolaterally from the foramen lacerum to the ventral jugular foramen. Approaching both segments of the ventral PCF first requires full exposure of the foramen lacerum, followed either by exposure of the anterior wall of cavernous sinus and paraclival internal carotid artery for upper segment access, or transection of pterygosphenoidal fissure and Eustachian tube mobilization for lower segment access. Combined with a CTM approach, the lateral extension of the surgical access can be improved for both upper and lower segment PCF approaches. Conclusion This study provides a detailed investigation of the microsurgical anatomy of the ventral part of PCF, relevant surgical approaches, and technical nuances that may facilitate its safe exposure intraoperatively.

Anatomical Step-by-Step Dissection of Complex Skull Base Approaches for Trainees: Surgical Anatomy of the Frontotemporal and Orbitozygomatic Craniotomies.

Introduction Although many neuroanatomic atlases have been published, few have detailed complex cranial approaches and pertinent anatomic considerations in a stepwise fashion intended for rapid comprehension by neurosurgery students, residents, and fellows. Methods Five sides of formalin-fixed latex-injected specimens were dissected under microscopic magnification. The frontotemporal and orbitozygomatic approaches were performed by neurosurgical residents and fellows at different training levels with limited previous experience in anatomical dissection mentored by the senior authors (M.P.C. and M.J.L.). Meticulous surgical anatomic dissections were performed until sufficient visual and technical completion was attained, with parameters of effectively demonstrating key surgical steps for educational training purposes. Following the completion of dissection and three-dimensional photography, illustrative case examples were reviewed to demonstrate the relative benefits and optimal applications of each approach. Results The frontotemporal and orbitozygomatic approaches afford excellent access to anterior and middle skull base pathologies, as well as the exposure of the infratemporal fossa. Key considerations include head positioning, skin incision, scalp retraction, fat pad dissection and facial nerve protection, true or false MacCarty keyhole fashioning, sphenoid wing drilling and anterior clinoidectomy, completion of the craniotomy and accessory orbital osteotomy cuts, dural opening, and intradural neurovascular access. Conclusion The frontotemporal and orbitozygomatic approaches are core craniotomies that offer distinct advantages for complex cranial operations. Learning and internalizing their key steps and nuanced applications in a clinical context is critical for trainees of many levels. The orbitozygomatic craniotomy in particular is a versatile but challenging approach; operative-style laboratory dissection is an essential component of its mastery and one that will be powerfully enhanced by the current work.

Diversity in Lacrimal Pathway Morphology Among Patients with Congenital Nasolacrimal Duct Obstruction.

Purpose: This prospective observational study aimed to explore the diversity in lacrimal pathway morphology among patients with congenital nasolacrimal duct obstruction (CNLDO) by examining dacryocystography (DCG) images. Patients and Methods: The study included 64 patients who underwent DCG before undergoing general anesthesia probing for unilateral CNLDO. Several parameters were measured from the lateral view of the DCG images: (1) the lacrimal sac (LS) and the nasolacrimal duct (NLD) angle, (2) the angle formed by the superior orbital rim (SOR), LS, and the NLD, (3) LS length, and (4) bony NLD length. Additionally, frontal views of the DCG images were utilized to measure (5) LS-NLD angle and (6) LS angle concerning the midline. Results: The average age of the patients was 34.3 months. The mean ± standard deviation of the measurements of the above parameters was (1) -1.2° ± 16.5° (range: -44.6° ± 46.6°), (2) -5.0° ± 10.3° (range: -24.0° ± 19.0°), (3) 10.2 ± 2.4 mm (range: 6.5-16.0 mm), (4) 8.0 ± 2.5 mm (range: 3.1-14.8 mm), (5) 15.6° ± 11.2° (range: -16.8° ± 41.0°), and (6) 15.1 ± 5.2° (range: 3.3°-29.8°). All parameters, except for parameter (3), conformed to a normal distribution. Conclusion: This study provides valuable anthropometric data derived from DCG images, highlighting the substantial variability in lacrimal pathway morphology among patients with CNLDO. Furthermore, anatomical constraints made probing with a straight metal bougie anatomically infeasible in 25.0% of the patients included in this study.

Understanding the morphology of the lacrimal pathway is crucial for the successful probing treatments in patients with congenital nasolacrimal duct obstruction (CNLDO). This study represents an initial effort to quantify anthropometric parameters of the lacrimal drainage system through dacryocystography images, specifically aiming to highlight the limitations of blind probing procedure. The results underscore significant variations in the morphology of the lacrimal drainage system among patients, which could impact diagnostic approaches and treatment strategies. Additionally, the findings suggest that patients with CNLDO who do not respond to blind probing may have underlying anatomical complexities. Therefore, rather than relying on repeated blind probing, employing dacryoendoscopy-guided probing under direct visualization could offer a more effective therapeutic alternative for complicated cases of CNLDO.

Liver surface depressions in the presence of diaphragmatic muscular bands on trans-illumination.

Traditional descriptions of liver anatomy refer to a smooth, convex surface contacting the diaphragm. Surface depressions are recognized anatomic variants. There are many theories to explain the cause of the depressions. We discuss the theory that these are caused by hypertrophic muscular bands in the diaphragm.

Investigating the biomechanical behaviour of tendon-loaded wrist joint using web-like kinematic network model.

The complexity of wrist anatomy and mechanics makes it challenging to develop standardized measurements and establish a normative reference database of wrist biomechanics despite being studied extensively. Moreover, heterogeneity factors in both demographic characteristics (e.g. gender) and physiological properties (e.g. ligament laxity) could lead to differences in biomechanical behaviour even within healthy groups. We investigated the kinematic behaviour of the carpal bones by creating a virtual web-like network between the bones using electromagnetic (EM) sensors. Our objective was to quantify the changes in the carpal bones' biomechanical relative motions and orientations during active wrist motion in the form of orb-web architecture. Models from five cadaveric specimens at different wrist positions: (1) Neutral to 30° Extension, (2) Neutral to 50° Flexion, (3) Neutral to 10° Radial Deviation, (4) Neutral to 20° Ulnar Deviation, and (5) Dart-Throw Motion - Extension (30° Extension/10° RD) to Dart-Throw Motion Flexion (50° Flexion/20° UD), in both neutral and pronated forearm have been analyzed. Quantification analyses were done by measuring the changes in the network thread length, as well as determining the correlation between the threads at different wrist positions. We observed similarities in the kinematic web-network patterns across all specimens, and the interactions between the network threads were aligned to the carpal bones' kinematic behaviour. Furthermore, analyzing the relative changes in the wrist web network has the potential to address the heterogeneity challenges and further facilitate the development of a 3D wrist biomechanics quantitative tool.

Exploring consistent ratios in morphometry of the proximal tibia: insights for knee arthroplasty.

INTRODUCTION: The current study, which delves into proximal tibia morphometric parameters in a Greek sample, not only analyzes whether specific linear distance ratios are consistent but also paves the way for a potential novel metric system for knee arthroplasty imaging studies using constant ratios. These findings could have significant implications for future enlarged research and clinical practice. METHODS: A total of 38 dried tibiae were evaluated by two independent investigators. The following distances were measured with a digital Vernier sliding caliper: (1) the mediolateral distance of the proximal surface (A), (2) the anteroposterior distance of the proximal surface (B), (3) The longitudinal length of the bone (C), (4) the line connecting the anterior margin of the proximal surface with the highest peak of the tibia tuberosity (D), (5) the depth of the proximal margin of the medial articular facet (AF) (medial plateau) (E) and (6) the depth of the proximal margin of the lateral AF (lateral plateau) (F). RESULTS: The A, B, C, D, E, and F mean distances were 71.3 mm, 47.4 mm, 340.2 mm, 37.1 mm, 42 mm, and 35.9 mm. Reliability analysis for each observer on all measurements revealed an interclass correlation (ICC) score of 0.975 (observer 1) and 0.971 (observer 2). The ratio A/B was 1.5, A/C was a constant 0.2, and D/C was 0.1. The ratio E/F was 1.2. The six measurements (A-F) showed excellent inter-observer reliability (all ICC values > 0.990). CONCLUSIONS: The study established constant ratios of the studied linear distances around the proximal tibia. Considering these ratios, asymmetrical tibial components in knee arthroplasty seem to replicate the native anatomy more closely. Furthermore, the distance from the anterior margin of the proximal surface to the tibial tuberosity peak, constituting one-tenth of the longitudinal length of the tibia, shows promise as a metric system for imaging studies, especially in assessing lesions around tibial components.

Dimension, Location and Clinical Importance of Supraorbital Foramen and Notch: A Combined Cadaveric and Dry Skull Study.

PURPOSE: The exit points of the supraorbital nerve and its branches hold significant importance in various medical procedures, including supraorbital endoscopic surgeries, forehead-facial aesthetic plastic surgeries, medical aesthetic applications and maxillofacial surgeries. Therefore, the primary objective of the present study was to precisely define the dimension, location and clinical significance of the supraorbital foramen/notch. By doing so, we aimed to enhance our understanding of this anatomical structure and its implications for surgical and aesthetic interventions in the supraorbital region. METHODS: For our study, we conducted anatomical dissections and bone measurements to assess the significance of anatomical variations of the supraorbital foramen/notch. We utilized a sample consisting of 28 cadavers and 38 skulls. The supraorbital foramen/notch was bilaterally analyzed in all 28 cadavers and 38 dry bones. We morphometrically analyzed the distance between the supraorbital foramen/notch and various anatomical landmarks, including the nasion, supraorbital margin, infraorbital margin, temporal crest, glabella, frontal cavity and midline of the face. Additionally, we measured the distance between the supraorbital foramen/notches and the frontal foramen/notches, and the width of the supraorbital foramen/notch and the distance between both supraorbital foramina/notches. RESULTS: There are 32 (57.14%) supraorbital  foramina, and the remaining are 24 (42.86%) supraorbital notches in cadavers and there are 36 (47.37%) supraorbital foramina, and the remaining are 40 (52.63%) supraorbital notches in skulls. We observed consistency in the dimension and location values of anatomical measurement parameters between cadavers and dry skulls on both right and left sides, with the exception of the parameter "distance from temporal crest" (p=0.042). Furthermore, our correlation analysis revealed a significant positive relationship between the right and left sides across all parameters, except for the following instances: in dry skulls, "distance from supraorbital margin" and in cadaver parameters, "distance from temporal crest, " "distance from frontal cavity" and "width." CONCLUSION: In our study, we observed that the distributions of supraorbital foramina and notches were nearly similar. Furthermore, our findings indicated comparable measurements between the right and left sides in both cadavers and skulls. These results suggest a degree of consistency in supraorbital anatomy within our study sample, regardless of the specimen type (cadavers or skulls) or laterality (right or left side). NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. 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.

Upper Limb Function in People With Upper and Lower Limb Loss 8 Years Postinjury: The Armed Services Trauma Outcome Study (ADVANCE) Cohort Study.

OBJECTIVE: Upper limb (UL) disability in people with UL amputation/s is well reported in the literature, less so for people with lower limb amputation/s. This study aimed to compare UL disability in injured (major trauma) and uninjured UK military personnel, with particular focus on people with upper and lower limb amputation/s. METHODS: A volunteer sample of injured (n = 579) and uninjured (n = 566) UK military personnel who served in a combat role in the Afghanistan war were frequency matched on age, sex, service, rank, regiment, role, and deployment period and recruited to the Armed Services Trauma Rehabilitation Outcome (ADVANCE) longitudinal cohort study. Participants completed the Disability of the Arm, Shoulder, and Hand (DASH) questionnaire, scored from 0 (no disability) to 100 (maximum disability) 8 years postinjury. Mann-Whitney U and Kruskal Wallis tests were used to compared DASH scores between groups. An ordinal model was used to assess the effect of injury and amputation on DASH scores. RESULTS: DASH scores were higher in the group with injuries compared to the group without injuries (3.33 vs 0.00) and higher in people with lower limb loss compared to the group without injuries (0.83 vs 0.00), although this was not statistically significant. In the adjusted ordinal model, the odds of having a higher DASH score was 1.70 (95% CI = 1.18-2.47) times higher for people with lower limb loss compared to the group without injuries. DASH score was not significantly different between people with major and partial UL loss (15.42 vs 12.92). The odds of having a higher DASH score was 8.30 (95% CI = 5.07-13.60) times higher for people with UL loss compared to the uninjured group. CONCLUSION: People with lower limb loss have increased odds of having more UL disability than the uninjured population 8 years postinjury. People with major and partial UL loss have similar UL disability. The ADVANCE study will continue to follow this population for the next 20 years. IMPACT: For the first time, potential for greater upper limb disability has been shown in people with lower limb loss long-term, likely resulting from daily biomechanical compensations such as weight-bearing, balance, and power generation. This population may benefit from prophylactic upper limb rehabilitation, strength, and technique.

OpenHands: An Open-Source Statistical Shape Model of the Finger Bones.

This paper presents statistical shape models of the four fingers of the hand, with an emphasis on anatomic analysis of the proximal and distal interphalangeal joints. A multi-body statistical shape modelling pipeline was implemented on an exemplar training dataset of computed tomography (CT) scans of 10 right hands (5F:5M, 27-37 years, free from disease or injury) imaged at 0.3 mm resolution, segmented, meshed and aligned. Model generated included pose neutralisation to remove joint angle variation during imaging. Repositioning was successful; no joint flexion variation was observed in the resulting model. The first principal component (PC) of morphological variation represented phalanx size in all fingers. Subsequent PCs showed variation in position along the palmar-dorsal axis, and bone breadth: length ratio. Finally, the models were interrogated to provide gross measures of bone lengths and joint spaces. These models have been published for open use to support wider community efforts in hand biomechanical analysis, providing bony anatomy descriptions whilst preserving the security of the underlying imaging data and privacy of the participants. The model describes a small, homogeneous population, and assumptions cannot be made about how it represents individuals outside the training dataset. However, it supplements anthropometric datasets with additional shape information, and may be useful for investigating factors such as joint morphology and design of hand-interfacing devices and products. The model has been shared as an open-source repository ( https://github.com/abel-research/OpenHands ), and we encourage the community to use and contribute to it.

Learning in context: Undergraduate students' knowledge and the content retention of anatomy between discipline-specific and integrated course approaches.

Undergraduate introductory human anatomy and human physiology courses are either taught as discipline-specific or integrated anatomy and physiology (A&P) sequences. An institution underwent a curricular revision to change the course approach from discipline-specific Human Anatomy and Human Physiology to an integrated A&P I and II sequence, allowing the unique opportunity to explore the potential role of contextual learning in academic achievement and content retention. Mediation and moderation analysis was used to evaluate lecture examinations, laboratory practical examinations, and anatomical content retention between the different course approaches. Undergraduate students in the integrated A&P I course approach performed significantly better on lecture assessments and had a higher anatomy content retention rate at the end of the year than students enrolled in the standalone Human Anatomy course. The lecture examination averages between Human Physiology and A&P II (the second course in the sequence), as well as the anatomy laboratory practical examinations, were not significantly different between discipline-specific and integrated course approaches. The results suggest contextual learning-providing physiological context to anatomical structures-increases the anatomical content retention and academic achievement overall.

The deltoid ligament complex is reliably visualised as four fascicles in two layers with 3D volumetric MRI in the ankles of 20 asymptomatic volunteers.

PURPOSE: The anatomy of the deltoid ligament is complex. There is agreement on the presence of superficial and deep layers but the number and frequency of fascicles remains controversial. Identifying injuries to specific components of the deltoid ligament may inform decision-making on their management. The anatomy was reviewed to establish the number and dimension of fascicles visible with three-dimensional (3D) volumetric magnetic resonance images (MRI). METHODS: Twenty ankles from asymptomatic healthy volunteers were imaged with 3D volumetric MRI. The presence of individual fascicles was recorded and measured in 3D. RESULTS: The median age of participants was 26 years (range: 20-37) of which 13 (65%) were female. All 20 ankles had a deltoid ligament formed of four fascicles in two layers: three fascicles in the superficial layer; tibionavicular (mean dimensions 22.5 × 10.0 × 2.4 mm), tibiospring (16.6 × 6.7 × 1.9 mm) and tibiocalcaneal (23.8 × 4.6 × 1.8 mm) and a deep layer consisting of the tibiotalar fascicle, which could be divided into two parts: anterior tibiotalar (mean dimensions 10 × 5.6 × 4.1 mm) and the significantly larger posterior tibiotalar (14.2 × 13.8 × 17.5 mm, p < 0.01). There were no additional fascicles observed. CONCLUSIONS: The deltoid ligament complex was consistently visualised as four fascicles (tibionavicular, tibiospring, tibiocalcaneal, tibiotalar) in two layers (superficial and deep) in all 20 ankles. The posterior part of the tibiotalar fascicle was the thickest of all the fascicles in the deltoid ligament. It is, therefore, possible to accurately identify the components of the deltoid ligament, and 3T MRI can be used to assess fascicle-specific injury, which will guide treatment and rehabilitation. LEVEL OF EVIDENCE: Level III.

The Impact of Vocal Tremor on Deglutition: A Pilot Study.

OBJECTIVE: Vocal tremor (VT) poses treatment challenges due to uncertain pathophysiology. VT is typically classified into two phenotypes: isolated vocal tremor (iVT) and essential tremor-related voice tremor (ETvt). The impact of phenotypes on upper aerodigestive tract physiology during swallowing remains unclear. Qualitative and quantitative measures were employed to characterize tremor phenotypes and investigate the effects on swallowing physiology. METHODS: Eleven ETvt participants (1 Male, 10 Female; x̄ age = 74) and 8 iVT participants (1 Male, 7 Female; x̄ age = 71) swallowed 20 mL boluses in cued and uncued conditions under standardized fluoroscopic visualization. Sustained/a/productions were captured to assess the rate and extent of fundamental frequency (F0) modulation. Penetration and Aspiration Scale (PAS) scores were obtained and swallowing biomechanics were captured using Swallowtail™ software. Participants also completed the Swallowing Quality of Life (SWAL-QOL) questionnaire. RESULTS: Hypopharyngeal transit was faster in both VT phenotypes compared with Swallowtail™ normative reference data. Total pharyngeal transit times, however, were only faster in patients with iVT, relative to reference data. No significant differences were observed on the SWAL-QOL or PAS between tremor phenotypes. SWAL-QOL scores revealed that these patients rarely reported dysphagia symptoms. CONCLUSIONS: Subtle differences in swallowing patterns were observed across VT phenotypes, possibly related to adaptive mechanisms resulting in quicker pharyngeal bolus transit. Most patients did not report swallowing issues or dysphagia symptoms. This study is foundational for larger studies on this challenging population. LEVEL OF EVIDENCE: 4 Laryngoscope, 2024.

Retroperitoneum revisited: a review of radiological literature and updated concept of retroperitoneal fascial anatomy with imaging features and correlating anatomy.

PURPOSE: Spread of disease in the retroperitoneum is dictated by the complex anatomy of retroperitoneal fasciae and is still incompletely understood. Conflicting reports have led to insufficient and incorrect anatomical concepts in radiological literature. METHODS: This review will discuss previous concepts prevalent in radiological literature and their shortcomings will be highlighted. New insights from recent anatomical and embryological research, together with imaging examples, will be used to clarify patterns of disease spread in the retroperitoneum that remain unexplained by these concepts. RESULTS: The fusion fascia and the renal fascia in particular give rise to planes and spaces that act as vectors for spread of disease in the retroperitoneum. Some of these planes and structures, such as the caudal extension of the renal fascia, have previously not been described in radiological literature. CONCLUSION: New insights, including the various fasciae, potential spaces and planes, are incorporated into an updated combined retroperitoneal fascial concept.

An accessory head of the extensor indicis: a rare case report.

PURPOSE: A deep knowledge of the variations of the posterior forearm musculature is crucial for assessing and diagnosing conditions in this region. Extensor indicis (EI) is one of the muscles in this region, which exhibits diverse anatomical variations. This report documents an extremely unusual form of the EI with an accessory head on the dorsum of the hand. METHODS: During routine dissection, an extremely rare presentation of the EI was found in the left forearm of a 94-year-old female cadaver. RESULTS: This unusual EI consisted of two muscle bellies. The traditional belly originated from the distal two-thirds of the ulna. The muscle became tendinous around the carpal area, distal to the extensor retinaculum. The tendon was subsequently joined by an accessory muscle belly originating from the distal radioulnar ligament. The EI tendon inserted onto the dorsal expansion of the index finger, ulnar to that of the extensor digitorum. The posterior interosseous nerve innervated the muscle. CONCLUSION: Herein, we report an extremely rare form of the EI. To our knowledge, EI with an accessory head has only been reported rarely over the past 200 years. Moreover, our report appears to be the first case with photographic details of this anatomical variation. Clinicians should be aware of this variation for proper diagnosis and treatment.