A Cadaveric Study on the Anomalous Extensors of the Hand

Background: The hands play a pivotal role in skilled movements. Anomalous muscles of the extensors of the hand are seen usually in anatomical dissections and during surgeries. Variations of the muscles in the dorsum of hand may be asymptomatic or may cause dorsal wrist pain, particularly if a muscle belly encroaches on and obstruct the wrist’s small extensor compartments deep to extensor retinaculum. Methods: A total of 54 upper limb specimens were used for the current study from the Anatomy Department of an undergraduate & postgraduate teaching Medical College in India. Incidence of additional muscle belly and its tendon in the posterior compartment of the forearm and dorsum of the hand were noted and photographed. Results: The anomalous muscle bellies and tendons in extensor compartment of forearm and dorsum of hand were observed in 10 limbs (18.5%) of 54 limbs. Of which, the extensor medii proprius (EMP) was 9.3%, extensor digitorum brevis manus (EDBM) was 3.7%. The numbers of the tendon of the extensor digitorum (ED) were varied in 3 limbs (5.6%). Conclusion: Knowledge of anatomical data of such variant muscles and additional belly or tendon in the extensor compartment of forearm and dorsum of hand is essential for surgeons to modify treatment plan, so as to avoid reporting error and of surgical procedures while operating on hand.

A rare bilateral variation on the dorsum of the hand: extensor digitorum brevis manus and extensor medii proprius / 대한해부학회지

A 78-year-old male cadaver showed bilateral anomalous muscles on the dorsum of the hand. An extensor digitorum brevis manus was noted on the dorsum of the right hand. It originated from the distal end of the radius and the radiocarpal joint ligaments and inserted into the metacarpophalangeal joint of the third digit. On the dorsum of the left hand, an extensor digiti medii proprius was identified. It originated from the distal third of the ulna near the extensor indicis proprius and the interosseous membrane and inserted into the metacarpophalangeal joint of the third digit. Awareness of these combined muscular variation would be helpful in understanding the identification of digital extensors and in requiring careful consideration for the reconstruction surgery of the hand.

Extensor Digitorum Brevis Manus / 대한정형외과학회잡지

Extensor digitorum brevis manus (EDBM) is a rare variation of the extensor muscle of the dorsum of the hand, which is found incidentally during surgery or magnetic resonance imaging (MRI). EDBM arises from the wrist capsule inferior to the extensor retinaculum, which frequently goes into the ulna side of the basis of the proximal phalanx between the 2nd and 3rd fingers. The aim of this report is evaluate to investigate the symptomatic mass on the dorsum of the hand and wrist using an image study (MRI or ultrasonography) to confirm whether it is a tumor or EDBM. Surgical excision was chosen as a treatment.

Músculo extensor anómalo de la mano: "extensor digitorum brevis manus" / Anomalous extensor hand muscle: extensor digitorum brevis manus

En la región dorsal de la muñeca y la mano, se describen varios músculos accesorios o supernumerarios, que pueden actuar como simuladores de entidades patológicas y producir síntomas clínicos (gangliones, quistes sinoviales, etc.). El diagnóstico clínico es cada vez más accesible; la ecografía y la resonancia magnética han permitido conocer su naturaleza y extensión. La presencia de este músculo, por lo general, pasa desapercibida y no causa síntomas, aunque puede producir clínica de tumefacción y dolor en el carpo; se acentúa con la actividad, sobre todo, aquellas que requieran la extensión forzada de la muñeca y los dedos. Puede manifestarse bilateralmente en un tercio de los pacientes y la incidencia no difiere entre los sexos. Cuando los síntomas son graves, hay que recurrir al tratamiento quirúrgico que consiste en la resección completa del músculo o en la división del retináculo extensor; con ambas técnicas se obtienen buenos resultados; en algunos casos, se lo ha usado como colgajo para reconstruir lesiones tendinosas en otros niveles. Este músculo es muy poco frecuente; la revisión bibliográfica de este trabajo ayudaría a considerar esta patología a la hora de realizar diferentes diagnósticos diferenciales en la región de la muñeca y la mano.

In the dorsal region of the wrist and hand, various accessory and supernumerary muscles are described; they can act as simulators and produce clinical entities (ganglion, synovial cysts, etc.). The clinical diagnosis is increasingly accessible; ultrasound and magnetic resonance have allowed to evaluate their nature and extent. The presence of this muscle usually goes unnoticed without symptoms, but it can cause swelling and pain in the carp; it is accentuated with activities, especially those requiring the forced extension of the wrist and fingers. It can manifest bilaterally in one third of patients and the incidence did not differ between males and females. When symptoms are severe, surgical treatment is indicated with the complete resection of the muscle or the division of the extensor retinaculum; both techniques achieve good results; in some cases, it has been used as a flap to reconstruct tendon injuries at other levels. The frequency of this muscle is very low; our literature review will help to consider this condition among the various differential diagnoses in the region of the wrist and hand.

A Cadaveric Study of Incidence, Morphology, Phylogeny and Classification of Extensor Digitorum Brevis Manus.

Introduction: A rare type of variation of extensor muscles on the dorsum of hand is extensor digitorum brevis manus (EDBM).It is a small muscle rarely present on the dorsum of the hand which can be misinterpreted a pathological mass on the dorsum of the hand. Aim: Aim of the present cadaveric study is to observe the incidence, anatomical morphology of EDBM and to study its phylogenetic significance. Material and Methods: Present study was conducted on 32 adult human cadaveric hands of which 24 were of male and 8 were of female cadavers. Results: The EDBM was observed in one incidence (3.1%) of the specimens. EDBM was found to be between the tendons of extensor digitorum for index and middle fingers. It was of Anatomical variant type I. Conclusion: The knowledge of incidence and morphology of EDBM is of greater relevance in clinical practice to rule out any pathological mass on the dorsum of the hand.

Double-Bellied Extensor Digitorum Brevis Manus: A Case Report.

Most of the anatomical variations are noted during the cadaveric dissections. A rare variation of the Extensor digitorum brevis manus was observed on the dorsal aspect of the right hand of a 69-year-old male cadaver. This atavistic muscle had two bellies which originated from the dorsal aspect of the lower end of radius and the capsule of the wrist joint respectively. The two bellies fused to form a single tendon which inserted into the ulnar side of the dorsal digital expansion of the middle finger. Posterior interosseous nerve innervated the two bellies. This muscle may be involved in the wrist pain or may be misinterpreted as a ganglion or a nodule upon radiological examination. This muscle may be used for reconstructive purposes.

Extensor digitorum brevis manus: a raremuscle on the dorsum of the hand

The extensor digitorum brevis manus is one of the rare anatomic variations which occur on the dorsum of the hand. Only some 295 articles were found worldwide in an extensive bibliographic review carried out in 2003. This muscle was dissected bilaterally on a male corpse at the Human Anatomy Laboratory of the Morphophysiological Department of the “Faculty of Medical Sciences of Minas Gerais”. It is an elongated, small muscle, originating at the carpal bones and at the extensor retinaculum and inserting into one of the tendons of the finger’s extensor muscle. Even though it does not present an essential function in the movement of the fingers nor the hand, it can lead to pain when hypertrophied, creating the need for clinical or even surgical treatment.