An Aberrant Abductor Digiti Minimi Muscle Crossing Guyon's Canal

Abstract

Anomalous hypothenar muscles in the wrist are relatively common with 47% prevalence, and their possible consequences associated with Guyon's canal are well known. The accessory of the abductor digiti minimi muscle (ADM) is known to be one of the causes of ulnar tunnel syndrome or ulnar artery thrombosis. A unique ADM was found in the volar wrist region of an 87-year-old male cadaver passing through Guyon's canal.

Ultrasound of the ulnar–palmar region of the wrist: normal anatomy and anatomic variations

“…15); less frequently, it is located between the two (Fig. 16) [22]. In our experience, the accessory muscle may also present two distinct bellies, radial, and ulnar to the UA, joining distally with the ADM (Fig.…”

Possible points of compression of the ulnar nerve: Tricks and traps that await clinicians from an anatomical point of view

“…However, an ADM can lead obliquely across the forearm and enter Guyon's canal. Nam et al (2017) report that in one case, it was located beneath the ulnar artery and above the UN; however, a range of spatial configurations is possible.…”

Aberrant accessory abductor digiti minimi manus muscle: a rare anatomical variation

“…Moreover, AADM's course via Guyon's canal may induce compression of the deep branch of the ulnar nerve and the ulnar vessels, which consists a major structural cause of Guyon's canal syndrome [5,21]. Therefore, hand surgeons and orthopedic surgeons in general, should consider the potential existence of an AADM muscle when diagnosing Guyon's canal syndrome.…”

“…The hypothenar eminence is formed by four muscles; the abductor digiti minimi muscle, the flexor digiti minimi brevis muscle, the opponens digiti minimi muscle, and the palmaris brevis muscle [1]. Many researchers have described abnormalities of the hypothenar muscles focusing mainly on their morphology and topography [2][3][4][5][6][7]. The hypothenar muscle with the greatest frequency of variations appears to be the abductor digiti minimi manus and the second more variable muscle is the flexor digiti minimi manus [7].…”