Higher and Bulkier Origin of the Lumbricals and their Clinical Relevance

Lumbricals are important small intrinsic muscles of the hand, which arise from the tendons of the flexor digitorum profundus in the palm distal to the flexor retinaculum and are inserted on to the dorsal digital expansion. Variations in the unipinnate/bipinnate pattern of lumbricals, absence of one or more muscles, origin from the superficial flexor tendons and flexor retinaculum have been reported earlier. In the present case, all four lumbricals were arising from the tendons of the flexor digitorum profundus, proximal to the flexor retinaculum in the anterior part of the forearm and extending into the palm through the carpal tunnel. However, there was no variation found with regard to their normal unipinnate (first two) and bipinnate (last two) pattern of origin. In the palm all the four lumbricals were found to be bulkier than their normal size, first one being the bulkiest. The bulky and high origin of lumbricals within the carpal tunnel makes the tunnel a compact space. Therefore, such variation is one of the predisposing factors for the carpal tunnel syndrome. Thus, the knowledge of such variant origin of lumbricals is helpful not only during carpal tunnel release but also during the magnetic resonance imaging (MRI) and ultrasound based diagnosis of carpal tunnel and during the flexor tendon repair and reconstruction.

Presence of Additional Head of Pronator Teres Muscle and Associated Neurovascular Variations: A Rare Case Report

Arm is a site for frequent injuries and it is involved in many surgical procedures. Variations in the arm have immense clinical significance. During the dissection of a right upper limb, brachial artery was found to divide into radial and ulnar arteries, 3cm above the inter-epicondylar plane. The ulnar artery and the median nerve were then passing through a tunnel formed by an extensive additional humeral head of the pronator teres muscle. Two centimetres long fibromuscular tunnel formed by the humeral head of the pronator teres was found to arise from the medial intermuscular septum and also from the fibrous arch form the shaft of the humerus to the medial intermuscular septum. In the same cadaver, the superior ulnar collateral artery was found to arise from the profunda brachii artery which is otherwise a branch of the brachial artery. Accurate knowledge of these variation patterns is of considerable clinical significance in conduct of surgeries of arm, fracture management of humerus and diagnosis of various compressive neuropathies.