Bilateral Appearance of the Abductor Digiti Minimi Accessorius Originating from the Palmaris Longus Muscle: a Case Report
Location
Lions Eye Center
Document Type
Poster
Start Date
28-4-2025 12:00 PM
End Date
28-4-2025 1:30 PM
Description
Introduction: Variations of the palmaris longus (PL) have been reported before, including a presentation named the abductor digiti minimi accessorius (ADMA) that appeared unilaterally in either the left or right upper extremities. However, the existence of a bilateral ADMA rising from PL has not been described previously. Purpose: To describe muscle variation on the human body. Methods: An unusual PL muscle was found in both left and right upper extremities while dissecting both forearms and hands of a 59 year old male cadaver in gross anatomy lab for physical therapy students in 2015. Results: The PL muscle originates from the medial epicondyle of the humerus and transitions into split yet connected tendon bundles at the upper quarter of the anterior forearm. These bundles continue down to the lower third of the forearm, where they fully separate into the proper PL tendon and a variant muscle mass (the ADMA muscle). The ADMA appears symmetrically on both the left and right forearms, arising from the palmaris longus (PL) and joining, rather than fusing with, the intrinsic abductor digiti minimi (ADM) muscle to insert at the medial base of the proximal phalanx of the little finger. It should be noted that while the PL tendon extends to fuse with the palmar aponeurosis, the ADMA continues its path distally and ulnarly, passing underneath the palmaris brevis muscle, immediately anterior to Guyon's canal. A small branch of the ulnar nerve, located just distal to the pisiform bone, courses medially to innervate the ADMA. Discussion: Secondary to the ADMA's position over the Guyon's canal, inflammation of the ADMA might lead to compression of the ulnar nerve. Combined wrist dorsiflexion and radial deviation could lead to ulnar nerve irritation due to compressive effect of the stretched ADMA as it passes over
Recommended Citation
Berggren, Brenden; Fluellen, Elizabeth; and Kieff, Jacob, "Bilateral Appearance of the Abductor Digiti Minimi Accessorius Originating from the Palmaris Longus Muscle: a Case Report" (2025). School of Allied Health Professions Research Day. 4.
https://digitalscholar.lsuhsc.edu/ahrd/2025/posters/4
Bilateral Appearance of the Abductor Digiti Minimi Accessorius Originating from the Palmaris Longus Muscle: a Case Report
Lions Eye Center
Introduction: Variations of the palmaris longus (PL) have been reported before, including a presentation named the abductor digiti minimi accessorius (ADMA) that appeared unilaterally in either the left or right upper extremities. However, the existence of a bilateral ADMA rising from PL has not been described previously. Purpose: To describe muscle variation on the human body. Methods: An unusual PL muscle was found in both left and right upper extremities while dissecting both forearms and hands of a 59 year old male cadaver in gross anatomy lab for physical therapy students in 2015. Results: The PL muscle originates from the medial epicondyle of the humerus and transitions into split yet connected tendon bundles at the upper quarter of the anterior forearm. These bundles continue down to the lower third of the forearm, where they fully separate into the proper PL tendon and a variant muscle mass (the ADMA muscle). The ADMA appears symmetrically on both the left and right forearms, arising from the palmaris longus (PL) and joining, rather than fusing with, the intrinsic abductor digiti minimi (ADM) muscle to insert at the medial base of the proximal phalanx of the little finger. It should be noted that while the PL tendon extends to fuse with the palmar aponeurosis, the ADMA continues its path distally and ulnarly, passing underneath the palmaris brevis muscle, immediately anterior to Guyon's canal. A small branch of the ulnar nerve, located just distal to the pisiform bone, courses medially to innervate the ADMA. Discussion: Secondary to the ADMA's position over the Guyon's canal, inflammation of the ADMA might lead to compression of the ulnar nerve. Combined wrist dorsiflexion and radial deviation could lead to ulnar nerve irritation due to compressive effect of the stretched ADMA as it passes over