Pectorobrachioepicondylaris musculoaponeurotic band: case description with evidence of median nerve compression.

Upper limb muscle variations can be encountered on imaging or at surgery. We report an unusual muscle and band found during routine dissection of the arm in a cadaver. This case is described and salient literature reviewed. A band was found that traveled from the insertion of the pectoralis major tendon distally and obliquely toward the medial intermuscular septum and medical epicondyle. Fibers of the brachialis were found to interdigitate into the band. A tunnel was formed that carried the median nerve and brachial vessels. Evidence of median nerve compression was observed. We considered this an example of a pectorobrachioepicondylaris muscle. However, some can lead to clinical presentations. Although the significance of the case reported herein is not certain, signs of median nerve compression were identified. We believe that the term pectorobrachioepicondylaris bests describes the muscle reported herein and that our case represents a previously unreported variant of this muscle.

The anatomy of the tendon of abductor pollicis longus and its morphological variations: An anatomical approach emphasizing the clinical relevance.

PURPOSE: The anatomical literature describes the abductor pollicis longus as a muscle with a single tendon inserting on the base of the first metacarpal bone, but investigations have shown that it often exhibits morphological variations. However, methodological approaches used to describe these variations have not been useful in a clinical context. Therefore, the purpose of this investigation was to study and relate such anatomical variations in a clinical context. BASIC PROCEDURES: Thirty upper limbs from the body donation program were dissected using standard procedures to identify the number of abductor pollicis longus (APL) tendons, their position, site of insertion, length, width and thickness. The presence or absence of the extensor pollicis brevis muscle was also noted. Inter and intra-observer reliability was analysed. MAIN FINDINGS: A total number of 71 tendons from the APL muscle were found in the thirty limbs. The most frequent distribution pattern was a main tendon inserted on the base of the first metacarpal and an accessory tendon inserted into the abductor pollicis brevis muscle. These tendons could divide into various tendinous slips that could insert in different locations. Also, clustering algorithms and classical statistical tests showed tendons inserting on the first metacarpal were longer than tendons not inserting on the first metacarpal (p = 0.03), while medial tendons and tendons from an APL muscle with supernumerary tendons were narrower (p < 0.001). The absence of the extensor pollicis brevis muscle was not related to the presence of supernumerary APL tendons. CONCLUSIONS: Radiological and surgical implications of these results are important when examining this region of the hand and wrist. The pathophysiology and treatment of de Quervain's tenosynovitis, trapeziometacarpal arthritis and trapeziometacarpal subluxation or laxity could be influenced by the results of our findings.