Accessory Head of Flexor Pollicis Longus Muscle and its Significance in Anterior Interosseous Nerve Syndrome: Case Report and Review

Abstract

SUMMARY:During the laboratory dissection of the fore arm, an accessory head of flexor pollicis longus muscle has been observed unilaterally in the right upper limb of a male cadaver. It took its origin from the under surface of flexor digitorum superficialis muscle just distal to the origin of this muscle from medial epicondyle. On further dissection we have noticed that, the accessory belly was running downwards to the medial aspect of the tendon of flexor pollicis longus muscle for its insertion. Its possible role in anterior interosseous syndrome is discussed in detail with a brief review.

Study of Accessory Head of Flexor Pollicis Longus in South Indian Population

“…This would cause strain over the normal range of movement and in turn there would be loss of precise and skillfull movement. The average length of muscle belly and the tendon length coincided with the studies made by Jones M & Abrahams [7], Potu B.k et al [12] . According to Mahakkanukrauh P et al [13] 4 types of relationships of AHFPL to AIN were noted.…”

Gantzer muscles and their applied aspects: an exceptional finding

“…(13) This abnormal muscle is found in more than 50% of individuals worldwide. (13) Earlier reports suggest that GFPL originates from under the surface of the FDS muscle and inserts into the ulnar side of the FPL muscle. (4)(5)(6) Our present case also reports similar results regarding the origin and insertion of GFPL unilaterally.…”

The Median Nerve at the Carpal Tunnel … and Elsewhere

“…A bifid median nerve may be predisposed to compression in the carpal tunnel because of its relatively higher cross-sectional area compared with a nonbifid median nerve. Bifid nerves represent 0.8% to 18% of carpal tunnel syndromes [283031] (Figure 5). …”

“…The difference in cross-sectional area between the nerve in the carpal tunnel (scaphoid-pisiform) and proximally at the level of the pronator quadratus muscle has better sensitivity (99%) and specificity (100%) than measurements obtained only at the level of the carpal tunnel, with an optimal cut off value of 2 mm². In patients with bifid median nerve, the optimal threshold for the difference is 4 mm² (specificity > 90%) [303140]. …”