Anat Cell Biol.  2022 Sep;55(3):390-393. 10.5115/acb.22.014.

A case report of an accessory flexor digitorum profundus indicis contributing the first lumbrical

• Malhotra A
• Kulesza R

• KMID: 2533368
• DOI: http://doi.org/10.5115/acb.22.014

Abstract

Variations of the musculature within the upper extremity have been widely documented, with clinical implications ranging from motor dysfunction to compressive neuropathies. Herein, we described an aberrant muscle that originated from the anterior proximal forearm, formed a tendon that coursed through the carpal tunnel, and converged with the flexor digitorum profundus muscle to contribute to the first lumbrical. Additionally, the second lumbrical consisted of two heads, originating from the index and middle finger tendons of flexor digitorum profundus. Documentation and recognition of such anatomic variants is important, as this anatomic pattern may contribute to anterior interosseous or median nerve compression, incoordination, complications during surgery, and other clinical manifestations.

Keyword

Muscles; Orthopedics; Forearm; Hand

Figure

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  Fig. 1 Shown in (A) is the distal forearm and hand from the dissected specimen. The median nerve (MN), flexor digitorum superficialis (FDS), and flexor digitorum profundus (FDP) are displaced. The aberrant muscle is indicated by a yellow arrowhead and is colored red. It courses between flexor pollicis longus (FPL) and FDP. The slip of FDP to the index finger is indicated by a red asterisk. The aberrant muscle contributed to the first lumbrical (cyan arrowhead). Shown in (B) is an enlarged view of the region indicated by the white box in (A). Again, the muscle is colored red and indicated by yellow arrowheads. The image in (B) clearly indicated the proximal attachments of the lumbricals. The union of the two slips of the second lumbrical is indicated by the white asterisk. FCR, flexor carpi radialis.

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  Fig. 2 Shown in (A) is the distal forearm and hand from the dissected specimen. The region indicated by the white dashed lines is shown enlarged in (B). In (A), the accessory muscle (yellow arrowheads; colored red) is seen to have proximal attachment to the interosseous membrane (green arrowhead) and distally from the anterior surface of the radius (cyan arrowheads). The support of the accessory muscle is shown in (B). The proximal muscle belly is colored red and indicated by a yellow arrowhead. The muscle received innervation from the anterior interosseous nerve (AIN) and arterial supply from the anterior interosseous artery (red arrowhead). The ulnar artery is indicated by the magenta arrowheads. MN, median nerve; FPL, flexor pollicis longus.

Reference

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