Accessory abductor digiti minimi muscle, less muscular than thought: an update on prevalence, morphology, and review of the literature.

The accessory abductor digiti minimi is not uncommon; however, patients are usually asymptomatic without neuropathic symptoms. The most common anatomic variant is a small muscle belly at the level of the pisiform with fascial morphology proximal to Guyon's canal and origin from the distal antebrachial fascia. A contiguous muscle belly extending from the distal forearm through the wrist occurs much less frequently. Clinicians should be familiar with these anatomic variants to enhance its recognition, understanding that a muscular variant is rarer than previously reported, but historically can serve as a potential source of clinical symptomatology and could be encountered during physical examination or wrist surgery.