Accessory head of extensor indicis

We present a rare case of an extensor indicis with an accessory muscle belly discovered during a routine dissection. This unique variation was found in a 94-year-old female cadaver. The dissection revealed an extensor indicis with two muscle bellies on the left side: a normal proximal belly and an accessory distal belly. The proximal belly originated from the distal two-thirds of the ulna and adjacent interosseous membrane.

The presence of extra muscles in the forearm and hand can pose challenges for surgeons and clinicians, potentially leading to conditions like the fourth compartment syndrome. This can cause pain and swelling due to increased pressure within the posterior compartment, compressing the posterior interosseous nerve. Such variations are important to understand for accurate diagnosis and treatment.

This case contributes to the limited existing literature on this rare anatomical variation, highlighting the need for further studies with larger sample sizes to determine its prevalence. Awareness of such variations is crucial for anatomists and clinicians in both diagnostic and surgical contexts.

Reference

Suwannakhan A, Yurasakpong L, Taradolpisut N, Somrit M, Chaiyamoon A, Georgiev G, Iwanaga J, Tubbs RS. (2024). An accessory head of the extensor indicis: a rare case report. Surg Radiol Anat, https://doi.org/10.5115/acb.23.289