Extensor Digiti Minimi Research Articles

Fetal development and growth of extensor tendons and their sheaths in the dorsal side of the wrist and hand: a histological study.

To understand considerable variations in number of adult extensor ten-dons at the dorsal side of the wrist and hand. We examined histological sections from 30 human fetuses of gestational age 7-39 weeks and crown-rump length 22-323 mm. At the carpal level, earlier or smaller fetuses showed a simpler configuration with fewer tendon slips, whereas later or larger fetuses had a greater number of tendon slips with considerable variations in number and topographical relationships. Tendon slips of the early extensor digitorum to the middle and ring fingers were always 1 or 2, but were seven or more at late term. A tendon of the extensor digitorum to the little fin-ger could not be distinguished from other tendons at the carpal bone level. At the meta-carpal bone level, however, it extended from the ring finger tendon toward two slips of the extensor digiti minimi tendon. At the distal carpal level at midterm and late term, in which the tendon sheath was lost, each of the extensor digitorum tendon slips further divided to provide a mediolateral linear cluster of thin bundles. This large number of tendon components joined and united together to provide a single tight tendon at the level of the metacarpophalangeal joints. The extensor pollicis longs tendon usually lost a membranous septation when it crossed the extensor carpi radialis brevis tendon. Tendon slips in the fourth and fifth canals of the sheath were most likely to reduce in number after birth depending on the mechanical demand.

Articular Surface Damage Following Headless Intramedullary Nail Fixation of Proximal Phalanx Fractures

Offering the benefits of rigid fixation while minimizing soft tissue dissection, intramedullary implants have become a popular choice among hand surgeons. Their placement often requires traversing or passing in proximity to joint surfaces. This study aimed to assess the damage to the articular cartilage of the base of the proximal phalanx resulting from antegrade placement of threaded headless intramedullary nails. A cadaveric study comparing two techniques for antegrade placement of threaded headless intramedullary nails was conducted in 56 digits. The first entailed a single 2.1 mm intramedullary nail placed via the dorsal base of the proximal phalanx, whereas the second used two 1.8 mm intramedullary nails inserted via the collateral recesses of the phalangeal base. All specimens were analyzed for articular surface damage with the cartilage defect measured as a percentage of total joint surface area. Damage to the extensor tendons was also assessed in a subset of specimens. No significant difference in the percentage of articular surface damage was observed, with an average 3.21% ± 2.34% defect in the single 2.1 mm nail group and a 2.71% ± 3.42% mean defect in the two 1.8 mm nails group. There was no articular surface injury in 18% of digits in each group. Damage to extensor tendons was seen in three (9.4%) specimens and in all cases involved either the extensor indicis proprius or extensor digiti minimi. Hardware insertion using either the dorsal base of the proximal phalanx or the collateral recesses of the phalangeal base both demonstrated minimal articular cartilage damage and infrequent injury to the extensor tendons. With proper technique for antegrade insertion into the proximal phalanx, the cartilage defect observed often encompasses only a small percentage of the overall joint surface area.

Quantitative anatomy of the extensor digiti minimi muscle in the growing human fetus.

Introduction Age-specific reference intervals for the extensor digiti minimi muscle (EDMM) in the human fetus may be relevant in the detailed evaluation of the musculoskeletal systems with potential relevant aspects for surgical treatment. The aim of the study was to examine the age-specific reference intervals and growth dynamics of the EDMM in relation to its length, width, projection surface area and volume. Material and methods The examined material included 70 human formalin-fixed fetuses of both sexes (37♀, 33♂) aged from 17 to 29 weeks. With the use of anatomical dissection every EDMM was visualized, recorded in a form of JPG formats and analyzed by the digital image analysis system and statistical methods. Results No variability of the EDMM was found. All the morphometric parameters of the EDMM revealed neither sex nor laterality differences. With fetal age most linear parameters of the EDMM concerning its examined lengths and widths increased in accordance with natural logarithmic functions. The only two exceptions to this referred to the belly width of EDMM measured at its mid-length and the tendon width of EDMM measured proximal to the extensor retinaculum of wrist, which both followed square root functions. The projection surface areas of the EDMM followed natural logarithmic functions, while the volumetric growth of the EDMM was proportionate to fetal age. Conclusions The variability of the EDMM in the human fetus is minimal. The morphometric data of the EDMM represents age-specific reference intervals of clinical significance. Morphometric parameters of the EDMM reveal neither sex nor laterality differences. The EDMM displays three different growth dynamics: from gradual growth deceleration according to both natural logarithmic functions (total length of the muscle and its tendons, belly length, tendon lengths, belly width at its origin, tendon width at its insertion, and projection surface areas) and square root functions (belly width at its mid-length and tendon width in the pre-retinacular segment) to a proportionate growth (total volume).

A detailed anatomical study of the muscles of the forearm and hand in the Anubis baboon (Papio anubis) in comparison with humans

The anatomy of the human forearm and hand has been described in great detail, including possible anatomical variations. For animals, this information is still not complete. The aim of this case study was to describe the anatomy of the muscles of the forearm and hand in one individual of the Anubis baboon and to compare this information with the available data on the subject and with the anatomical standard and possible variations in humans. The biggest differences were noted in the extensor digiti minimi, where two separate muscle bellies were dissected. We believe that in this individual it was the extensor digiti quarti proprius and extensor digiti quinti proprius muscles. Anatomical standard has not yet been established for the thenar, hypothenar, and contrahentes muscles in the deep layer of the muscles of the forearm of the baboon and literary sources differ notably in some information. Determining the anatomical standard and anatomical variability of individual structures in animals is an important contribution to the field of veterinary surgery and orthopaedics.

New Insights into Boxer's Knuckle Injury of the Little Finger.

The original description of boxer's knuckle injury of the fifth ray mentions that the injury occurs between the extensor digitorum communis (EDC) and the extensor digiti minimi (EDM). Subsequent reports claim similar findings. Anatomical studies show that the EDC of the fifth ray is absent in most patients, while the EDM is generally composed of two slips. We present a modification of the current description of boxer's knuckle injury of the little finger based on the correlation between advanced preoperative 3D imaging and intraoperative findings. Five patients were investigated preoperatively using high-resolution ultrasound and 3D tendon reconstruction-based MR arthrography. Surgical exploration identified the lesion site relative to the EDM and EDC. All patients had two slips of the EDM and no EDC to the fifth ray. The injury appeared as a longitudinal tear of the EDM between its two slips. The mean gap was 7.8 mm (range 4.5-10 mm) on the pathological side vs. 1.3 mm (range 1-2 mm) on the healthy contralateral side. We believe that previous descriptions of boxer's knuckle of the fifth ray are inaccurate. High-resolution ultrasound and 3D reconstructions based on MR arthrography are reliable diagnostic tools allowing to locate the injury with precision.

Novel Therapeutic Approach for Extensor Digiti Minimi Tendon Traction in Chronic Ulnar-Sided Wrist Pain Diagnosed as Triangular Fibrocartilage Complex Injury: A Case Report

Novel Therapeutic Approach for Extensor Digiti Minimi Tendon Traction in Chronic Ulnar-Sided Wrist Pain Diagnosed as Triangular Fibrocartilage Complex Injury: A Case Report

The Medial Triquetrohamate Portal: A New Portal in Wrist Arthroscopy. Anatomical Study.

Introduction Continuing advances in wrist arthroscopy and better understanding of carpal conditions have created the need to design new wrist access portals that facilitate the implementation of new surgical techniques. The aim of this study was to define and verify the safety of the medial triquetrohamate (MTH) portal. Description of the technique The MTH portal is located about 5-10 mm ulnar and 2-3 mm distal to the midcarpal ulnar portal, ulnar to the extensor digitorum communis (EDC) tendon of the fourth and fifth fingers, and radial to the extensor digiti quinti (minimi) (EDQ) tendon. Methods An anatomical study was performed on 15 upper limb specimens from 15 human cadavers. Iatrogenic injuries to potentially at-risk neurovascular and tendinous structures were assessed, and the distance from the portal to these structures was measured. Results There were no iatrogenic injuries to the structures at risk. Mean distances from the MTH portal to the EDC tendon of the fourth and fifth fingers and to the EDQ tendon were 4.67 ± 0.35 mm and 7.27 ± 0.18 mm, respectively. No differences were observed between the left and right wrists. The distance from the MTH portal to the dorsal sensory branch of the ulnar nerve was 15.07 ± 0.44 mm. The structure with the highest risk of injury was the EDC tendon of the fourth and fifth fingers, with a distance of less than 5 mm. Conclusions The MTH portal is safe, reproducible and facilitates the implementation of various techniques related to midcarpal pathology.

Extensor Tendon Rupture in Ulnar Impingement Syndrome: A Case Report

Ulnar impingement syndrome is caused by a shortened ulna impinging on the distal radius and causing a painful, disabling pseudoarthrosis. Vaughan-Jackson syndrome is characterized by a disruption of the digital extensor tendons, beginning on the ulnar side with the extensor digiti minimi (EDM) and extensor digitorum communis (EDC) tendon of the small finger. While ulnar impingement and Vaughan-Jackson syndrome are not uncommon, it is rare to observe the two conditions occurring simultaneously. We report a unique case of ulnar impingement syndrome presenting with Vaughan-Jackson syndrome, revealing that the degenerative changes from ulnar impingement syndrome can cause attrition rupture of the EDM and EDC tendon of the little finger. This entails increased clinical significance of ulnar impingement, because in addition to its potential to cause debilitating pain, there is also consequence of functional deficits if extensor tendon rupture were to occur due to progressive degenerative changes. The surgical management of distal radioulnar joint (DRUJ) arthritis arising from ulnar impingement may include various intra-operative techniques to prevent post-operative extensor tendon rupture.

Optimizing electrode positions on forearm to increase SNR and myoelectric pattern recognition performance

With the advances in electromyography-based human–computer interaction, particularly in myoelectric prosthetic hands, the position of electromyography electrodes has gained less attention from researchers. However, the performance of hand movement recognition significantly varies with the change of electrode position around the forearm muscles and along the length of the forearm muscles. To find the robust position on the forearm, this study performs a comprehensive and systematic investigation of the feasibility of hand movement recognition using electromyogram (EMG) signals concurrently recorded for sixteen electrode arrays on the forearm. The obtained results indicate that the electrode array placed on the middle of the extensor digitorum communis and extensor digiti minimi performs better than other electrode positions around the forearm. In addition, multiple electrode arrays placed near to elbow joint achieve a significantly higher signal to noise ratio and signal to movement artifact ratio. In addition to improved EMG signal quality, the recommended positions on the forearm significantly overperform in hand movement recognition and it is validated with five well-known feature extraction methods, various window sizes, and three classification algorithms. In this study, the electrode arrays near to elbow joint on the forearm achieve an F1 score of 98.28% to 98.80% with a linear discriminant analysis classifier. Therefore, this study clearly demonstrates the feasibility of recommended forearm positions for hand movement recognition. As these electrode positions are near to elbow joint, so, it is expected that these positions will be available in most amputees and utilized for improved hand movement recognition.

Bilateral Digital Extensor Hypoplasia Correction: A Case Report and Systematic Review.

Digital extensor hypoplasia (DEH) is a rare malformation that presents with loss of active finger extension at the metacarpophalangeal (MCP) joints. Descriptions of optimal treatment and outcomes in this population are sparse. We describe successful operative treatment of a child with DEH involving the extensor digitorum communis, extensor digiti minimi, and the extensor indicis proprius tendons. The 5-year-old male patient was referred for severe limitation on bilateral finger extension since birth. He had been previously diagnosed with arthrogryposis and managed conservatively. Due to lack of improvement, magnetic resonance imaging was done evidencing hypoplasia/aplasia of the extensor tendons. The patient underwent successful tendon transfers using extensor carpi radialis longus to the common extensor tendons, and one hand required an additional tenolysis procedure. 2 years postoperatively, his MCP position and finger extension are markedly improved, and he is able to grip objects without limitation or difficulty. The patient returned to full activity without restriction.

Lateral Ulnar Collateral Ligament of the Elbow Joint: Reconsideration of Anatomy in Terms of Connection with Surrounding Fibrous Structures.

To improve the clinical results of lateral ulnar collateral ligament (LUCL) reconstruction of the elbow joint, better understanding of the anatomy of the aponeuroses and joint capsule could be relevant. This study considers the previously described anatomy of the LUCL in relation to the related aponeuroses and joint capsule rather than as a discrete ligament. We hypothesized that the deep aponeuroses of the superficial extensor muscles and supinator form a relevant portion of the joint capsule previously defined as the LUCL. Twenty-four elbows (12 right) from 21 embalmed cadavers (age at the time of death, 54 to 99 years) were included in the study. Twenty elbows were studied macroscopically and 4, histologically. The joint capsule was detached from the bones, and local thickness was quantitatively analyzed using micro-computed tomography (micro-CT). The supinator aponeurosis and joint capsule intermingled to form a thick membrane (mean and standard deviation, 4.8 ± 1.2 mm), which we termed "the capsulo-aponeurotic membrane." It was thicker than the anterior (1.3 ± 0.4 mm) and posterior (2.5 ± 0.9 mm) parts of the capsule of the humeroradial joint (p < 0.001). The capsulo-aponeurotic membrane had a wide attachment on the distal part of the extensor digitorum communis and extensor digiti minimi (EDC/EDM) origin of the humerus, the lateral part of the coronoid process, and the posterior part of the radial notch of the ulna. The humeral attachment had a fibrocartilaginous structure. The deep aponeuroses of the EDC and extensor carpi ulnaris (ECU) were connected to the capsulo-aponeurotic membrane. The capsulo-aponeurotic membrane was composed of the supinator aponeurosis and joint capsule and was attached to the lateral epicondyle of the humerus, radial side of the coronoid process, and posterior part of the radial notch on the ulna. The entire structure appeared identical to the commonly defined lateral collateral ligament. The most posterior part was connected to the EDC and ECU aponeuroses, which is commonly labeled the LUCL but does not exist as a discrete ligament. Consideration of the accurate anatomy of the extensive attachment of the capsulo-aponeurotic membrane could provide useful clues for improvement in techniques of LUCL reconstruction and lateral epicondylitis pathology.

Is It Possible to Perform Fifth Carpometacarpal Joint Arthroscopy? Cadaveric Study on Its Feasibility, Safety, and Potential Hazards in Portal Creation.

Background Fifth carpometacarpal joint (CMCJ) fracture dislocation is a relatively rare injury and most will require operative treatment because of its unstable nature. Improper reduction and fixation lead to joint surface destruction, pain, and reduced grasping power. Intra-articular fragment reduction is often obscured by dorsally displaced ulnar fragment. Therefore, fifth CMCJ arthroscopy can be advantageous in assisting intra-articular fragment reduction. However, there is no detailed description of the portal landmarks or portals' relationship with adjacent important structures in the literature. Purposes To explore the feasibility and safety of fifth CMCJ arthroscopy, locations of the portals are examined in cadaveric hand specimens. Their proximity to important anatomical structures such as dorsal cutaneous branch of ulnar nerve (DCBUN), ring finger and little finger extensor digitorum communis (EDC), and extensor digiti minimi (EDM) is measured. Methods Fifth CMCJ arthroscopy is performed on 11 cadaveric hand specimens by specialist-level surgeon. The portals are marked and portal positions are further confirmed under the fluoroscopy. Then the cadaveric specimens were undergone anatomical dissection by specialist-level surgeon. During dissection, the spatial relationship between the portal positions and DCBUN, EDC to ring finger and little finger, and EDM is identified. The distance between the portals and the above important structures was measured in millimeters. Results DCBUN was consistently found between fourth metacarpohamate (4-MH) and fifth metacarpohamate (5-MH) portals, with it being closer to the latter (mean distance, 2.03 mm; range, 0-4.43 mm; standard deviation [SD], 1.09 mm). The closest tendon for 4-MH portal is ring finger EDC (mean distance, 2.65 mm; range, 0-5.89 mm; SD, 1.78 mm), while 5-MH portal and accessory portal were closest to EDC (mean distance, 1.88 mm; range, 0-3.69 mm; SD, 1.25 mm) and EDM (mean distance, 7.79 mm; range, 6.63-10.72 mm; SD, 1.49 mm), respectively. During the process of specimen dissection, we found no damage to the above structures after portal introduction. Conclusion The above findings support the use of fifth CMCJ arthroscopy, which can be used for assisted reduction in fifth metacarpal base fracture dislocation and hamate body fracture. Gentle soft tissue spreading technique during portal creation prevents injury to the important structure surrounding the portals. Level of evidence This is a Level V study.

Correction of ulnar claw hand and Wartenberg’s sign

Ulnar claw hand usually occurs when the ulnar nerve is damaged distally. Claw hand deformity is characterized by metacarpophalangeal hyperextension and interphalangeal flexion, making it impossible to oppose the fingers and thumb. Bouvier’s test is used to guide the procedure. Palliative surgery requires prior preparation of paralytic hands. In case of a positive Bouvier’s test, Zancolli’s lasso technique is preferred because of its effectiveness. Capsuloplasty with anteroposterior transosseous fixation is used if the bone is strong enough and when flexor digitorum profondus muscle is inactive and does not allow flexor digitorum superficialis tendon transfer. In case of a negative Bouvier’s test with interphalangeal extension deficit of 45° of less, direct interossei muscle restoration techniques by active transfers are performed. If the interphalangeal extension deficit is more than 45°, proximal interphalangeal arthrodesis is indicated.Wartenberg first described actively irreducible abduction of the little finger. Wartenberg’s sign is seen when ulnar paralysis occurs, and during ulnar nerve regeneration. Treatment of isolated Wartenberg's sign consists of re-routing the extensor digiti minimi. Among the other techniques, Belmahi’s “tie lasso” is preferred when flexible claw hand is associated with Wartenberg’s sign.

Compartments of the antebrachial fascia of the forearm: clinically relevant ultrasound, anatomical and histological findings.

Acute compartment syndrome is defined as a limb-threatening condition caused by bleeding or oedema in a closed muscle compartment surrounded by fascia or bone. It is most commonly encountered in theforearm, which has three compartments: posterior, anterior and lateral. These are surrounded and closed in by the antebrachial fascia, formed by dense connective tissue that facilities their study on ultrasound and is key to fasciotomy treatment. The purpose of this study was to broaden existing ultrasound, anatomical and histological knowledge of the fascia of the forearm to facilitate their identification on ultrasound, with possible clinical and therapeutic applications. The study was performed in 50 cryopreserved upper limbs from adult cadavers from the dissection room of the Faculty of Medicine and Health Sciences. They were examined on ultrasound and subsequent anatomical dissection and microscopy to study the fascia and its relationship with different muscles of the forearm compartments. Distinct anatomical relationships were observed on ultrasound and dissection between the fascia and the extensor carpi ulnaris, extensor digiti minimi, and anconeus muscle in the posterior compartment, and the flexor carpi radialis and flexor carpi ulnaris in the anterior compartment. They were isolated by the antebrachial fascia and had distinct relationships with the neurovascular structures. These results demonstrate that high-definition ultrasound enables us to locate the antebrachial fascia and particular muscles with a distinct relationship with neurovascular structures. This helps better identify these structures, facilitating diagnosis of any pathology in the area, with potential therapeutic and clinical applications.

A study on correlation between surface measurement of limbs and underlying tendon grafts used for reconstructive surgeries

Introduction: Tendon transfer restores balance to the hand which has lost its power due to tendon or muscle destruction. There are various factors which are taken into account while selecting a graft for reconstructive surgeries such as availability, length, expendability of graft tendon. The purpose of this study is to correlate the surface measurement of upper limb and lower limb using anatomical landmarks and underlying tendon lengths used for grafting. This will provide an idea for estimation of underlying donor tendon lengths by easily measured surface measurements of upper and lower limbs. Materials and Methods: The study was conducted on 30 cadaveric upper and lower limbs collected in the department of anatomy, AIMS&RC, Devanahalli, Bengaluru. Lengths of commonly harvested tendons used for grafting were measured. In upper limb, tendons of palmaris longus, extensor digiti minimi and extensor indices were selected. In lower limb, tendons of plantaris and extensor digitorum longus of 2nd toe were selected. Surface measurement of upper limb and lower limbs were measured using bony land marks. Correlation between surface measurement of limbs and lengths of underlying tendons used for grafting were analyzed. By using, the univariate least square regression model, tendon multiplier is generated for each tendon, which gives the tendon length in donors by using the surface measurements of upper and lower limbs. Results: Mean tendon lengths of palmaris longus is 15.53±4.7 cm, extensor digiti minimi is 19.7±1.9 cm, extensor indices is 19.1±1.2 cm, plantaris is 35.97±2.7 cm and extensor digitorum longus of second toe is 27.93±2.9 cm. Tendon multiplier for the tendon of palmaris longus is 0.66, for extensor digiti minimi is 0.53, for extensor indices is 0.31, for plantaris is 0.91 and extensor digitorum longus is 0.51. Mean surface measurement of upper limb is 27.5±2.31 cm and lower limb is 37.43± 2.6 cm. Conclusion: While selecting tendons for graft, length of d

Practical ultrasonographic technique to precisely identify and differentiate tendons and ligaments of the elbow at the level of the humeral epicondyles: anatomical study

ObjectivesTo develop a practical step-by-step technique to precisely identify and differentiate tendons and ligaments attaching to the humeral epicondyles, to confirm through gross anatomical study the accurate structure identification provided by this technique and to determine the frequency at which each structure can be identified in healthy volunteers.Materials and methodsFirst, ten fresh frozen cadavers (6 men, age at death = 58–92 years) were examined by two musculoskeletal radiologists and a step-by-step technique for the identification of tendons and ligaments at the level of humeral epicondyles was developed. Second, the accurate identification of structures was confirmed through gross anatomical study including anatomical sections on five specimens and layer-by-layer dissection technique on five others. Finally, 12 healthy volunteers (6 men, average age = 36, range = 28–52) were scanned by two radiologists following the same technique.ResultsAn ultrasonographic technique based on the recognition of bony landmarks and the use of ultrasonographic signs to differentiate overlapping structures was developed and validated through gross anatomical study. In healthy volunteers, most tendons and ligaments were identified and well-defined in ≥ 80% of cases, except for the extensor carpi radialis brevis and extensor digiti minimi tendons on the lateral epicondyle (having common attachments with the extensor digitorum communis) and the palmaris longus tendon on the medial epicondyle (absent, or common attachment with the flexor carpi radialis).ConclusionA step-by-step approach to the ultrasonographic assessment of tendons and ligaments at the humeral epicondyles allowed accurate identification of and differentiation among these structures, in particular those relevant to pathological conditions.

The Branching and Innervation Pattern of the Radial Nerve in the Forearm: Clarifying the Literature and Understanding Variations and Their Clinical Implications.

Background: This study attempted to clarify the innervation pattern of the muscles of the distal arm and posterior forearm through cadaveric dissection. Methods: Thirty-five cadavers were dissected to expose the radial nerve in the forearm. Each muscular branch of the nerve was identified and their length and distance along the nerve were recorded. These values were used to determine the typical branching and motor entry orders. Results: The typical branching order was brachialis, brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, supinator, extensor digitorum, extensor carpi ulnaris, abductor pollicis longus, extensor digiti minimi, extensor pollicis brevis, extensor pollicis longus and extensor indicis. Notably, the radial nerve often innervated brachialis (60%), and its superficial branch often innervated extensor carpi radialis brevis (25.7%). Conclusions: The radial nerve exhibits significant variability in the posterior forearm. However, there is enough consistency to identify an archetypal pattern and order of innervation. These findings may also need to be considered when planning surgical approaches to the distal arm, elbow and proximal forearm to prevent an undue loss of motor function. The review of the literature yielded multiple studies employing inconsistent metrics and terminology to define order or innervation.

Prevalence of the extensor digitorum, extensor digiti minimi and extensor indicis tendons and their variations

We aimed to investigate tendon variations of the extensor digitorum (ED), extensor digiti minimi (EDM), and extensor indicis proprius (EIP) muscles. Our study was performed on 43 fetal cadavers (86 extremities), aged between 17 and 40 weeks of gestation. The number of ED tendons varied from three to six, proximal to the extensor retinaculum (ER), and from three to eight, distal to the ER. The ED most often had four tendons, both proximally and distally from the ER. The ED tendons of the fourth finger were observed to be most frequently duplicated. The most common juncturae tendinum (JT) was type 1 in the second intermetacarpal space (IMCS), type 2 in the third IMCS, and type 3r in the fourth IMCS according to von Schroeder classification. The number of EIP and EDM tendons varied from one to two and from one to five, respectively. The EIP double tendons inserted both into the ulnar and palmar sides of the extensor digitorum of the second finger, which had not been reported in the literature. In our study, 7% of hands had variant muscles. In 4.7% of hands, the extensor indicis et medii communis was observed, while the extensor medii proprius and the extensor digitorum brevis manus were observed in 1.2% and 1.2% of hands, respectively. Knowing the prevalence of the ED, EDM and EIP tendons and their variations in the fetal period should help to treat partial loss of hand function or injury after birth and to correct congenital hand deformities.

Variation in the morphology of the extensor pollicis longus and extensor digitorum muscles: A case report

This case report aims to highlight the variation in the morphology of the extensor pollicis longus (EPL) and the extensor digitorum (ED) muscles. EPL originates from the posterolateral surface of the ulna, and the ED originates from the lateral epicondyle of the humerus. Both of these muscles are innervated by the radial nerve. EPL’s primary function serves to extend the pollex, while the ED serves to aid in the extension of the metacarpal phalangeal, proximal interphalangeal, and distal interphalangeal joints of digits 2 through 5. During routine anatomical dissections of 48 upper limbs from 24 cadavers (n=24) at Oakland University William Beaumont School of Medicine, one adult female (75‐years‐old) was observed to have an EPL with an accessory tendon attaching on the 2nd metacarpal‐phalangeal joint and an accessory tendon of the ED inserting on the distal phalanx of the pollex unilaterally on the left side. The EPL is known to be one of the most anatomically consistent structures with its tendon, only inserting into the pollex (Kim, Lee, &amp; Baek). This variation of the EPL was described as extensor pollicis et indicis accessorius, which was found in 1.2% of the cadavers (n=431) in Yoashida’s study. Although there are a few isolated patient cases describing the similar ED variation, such as in Hanrahan et al., very few results have been found regarding the prevalence of the accessory ED muscle belly in the general population. It is likely that the ED tendon inserting into the pollex weakly assists with the extension function. Additional variations of the extensor indicis muscle providing an accessory tendon to the 3rd digit and extensor digiti minimi muscle providing an accessory tendon to the 4th digit were noticed bilaterally on the same cadaver. The knowledge of these variations will be vital in proper surgical planning for tendon transfers, grafts, and transplantations.

Extensor digiti minimi muscular flap: From a clinical case to an anatomical study

We present a case report of a failed posterior interosseous flap with distal pedicle rescued by an extensor digiti minimi (EDM) island pedicle flap supplied by the posterior interosseous artery (PIOA) in reverse flow to cover a soft tissue defect in the hand of a 25-year-old man. We subsequently performed an anatomical study on 5 cadaver limbs to determine the EDM muscle's vascularization: it was segmental, multiple and came from the PIOA. The rotation arc reached the dorsal side of the metacarpophalangeal (MCP) joints, as well as the distal part of the thumb. The indications selected are the same as those of the distal pedicle flap: defect on dorsal side of the hand and MCP joints, coverage of carpal tunnel, failure of posterior interosseous flap. This study describes a new flap and adds to our understanding of the EDM muscle's vascularization.