Bilateral Morphological Variation of Abductor Pollicis Longus and Extensor Pollicis Brevis Tendons: A Cadaveric Case Report with Clinical Perspective

Concurrent morphological variations of abductor pollicis longus (APL) and extensor pollicis brevis (EPB) are seldom reported in literature. Extra slips of APL and EPB are clinically significant as they are used to reconstruct the ruptured tendons in the hand. Herein, we report bilateral morphological variations of APB and EPB in a male cadaver. On each side of forearm, APL was divided into two tendinous slips within the first compartment of extensor retinaculum. One of these slips inserted on to the radial side of base of first metacarpal bone close to the insertion of EPB, and the other slip inserted on to both abductor pollicis brevis and opponens pollicis. EPB divided into two tendons slips deep to the extensor retinaculum. These slips were found to be inserted on to the dorsal surface of the base of proximal phalanx while the other inserted on to the radial aspect of the base of first metacarpal bone, close to the insertion of APL tendon. These additional slips are frequently associated with first carpo-metacarpal subluxation and de Quervain’s syndrome and may be responsible for the clinical manifestations of these diseases. In addition, knowledge of the morphological variations of APL and EPB can aid orthopaedic and plastic surgeons in performing successful tendon transplants.

A Variant Extensor Pollicis Brevis Crossing the Anatomical Snuff Box / 계명의대학술지

During an educational dissection, accessory tendon of the extensor pollicis brevis muscle was found on the left side in a Korean cadaver. The abductor pollicis longus, extensor pollicis brevis, and extensor pollicis longus muscles showed normal morphology and course: however, narrow muscle belly originated between the extensor pollicis brevis and extensor pollicis longus muscles. It crossed the anatomical snuff box and then inserted on the base of the distal phalanx of the thumb. The author describes this previously novel case report and discusses the clinical implications of such a variant.

Unusual topography of posterior antebrachial musculature in the first osseofibrous compartment of wrist: clinicomorphological appraisal / Topografía inusual de la musculatura antebraquial posterior en el primer compartimento osteofibroso de la muñeca: valoración clínico-morfológica

Anatomical variations of abductor pollicis longus and extensor pollicis brevis are important in clinical assessment of diseased and traumatized hand. The present case reports an unusual fusion of muscle bellies of abductor pollicis longus and extensor pollicis brevis with two separate tendons of insertion, the medial tendon inserted into the base of first metacarpal and the lateral tendon into the abductor pollicis brevis muscle. Knowledge of such anatomical variations is of utmost importance in the management of De Quervain's disease and reconstructive surgeries of hand.

Las variaciones anatómicas de los músculos abductor largo del pulgar y extensor corto del pulgar son importantes en la evaluación clínica de la mano enferma y traumatizada. El presente caso informa una inusual fusión de los vientres musculares de los Mm. abductor largo del pulgar y extensor corto del pulgar con dos tendones de inserción separados, el tendón medial se insertó en la base del primer metacarpiano y el tendón lateral en el músculo abductor corto del pulgar. El conocimiento de estas variaciones anatómicas es de importancia en el manejo de la enfermedad de De Quervain y cirugía reconstructiva de la mano.

Variations of Insertions of the Abductor Pollicis Longus and the Extensor Pollicis Brevis in Korean / 대한정형외과학회잡지

The purpose of this study was the presence of accessory tendon and its anatomical variation of insertion of the abductor pollicis longus and extensor pollicis brevis. 1. Among 46 cases, all had one or more accessory tendon except one which inserted into the base of the first metacarpal bone on its anterolateral surface with a single tendon. 2. Among 45 cases (which had one or more accessory tendon), the abductor pollicis longus tendon inserted into the trapezium in 30 cases(66.6%), and thenar muscles in 38 cases (84.4%). 3. Among 46 cases, the extensor pollicis brevis tendon inserted into the proximal phalanx in 30 cases(65%) and into the distal phalanx with extensor pollicis longus in 8 cases (18%) and into both in 8 cases (18%). 4. Among 22 cadavers, symmetry of insertion of the abductor pollicis longus noticed in 16 cases (88 and extensor pollicis brevis in 21 cases (95%).