Variant abductor pollicis longus muscle: a case report

Area of Science:

• Anatomy
• Human Anatomy
• Musculoskeletal System

Background:

• The abductor pollicis longus (APL) muscle is known for variations in its attachments.
• Split insertions of the APL muscle are common in non-human primates like chimpanzees, gorillas, and gibbons.

Observation:

• This study details an anomalous APL muscle originating from the posterior radius and ulna.
• The muscle coursed deep to the extensor retinaculum.
• Uniquely, the APL tendon reformed into a muscular belly on the first metacarpal before attaching to the proximal phalanx.

Findings:

• A rare anatomical variation of the abductor pollicis longus muscle was identified.
• The anomalous APL muscle exhibited an unusual attachment to the base of the proximal phalanx.
• This variation may significantly alter thumb abduction mechanics.

Implications:

• This rare APL variation has potential implications for thumb biomechanics.
• Understanding such anomalies is crucial for reconstructive surgeries involving the thumb.
• The finding holds academic interest for comparative anatomy and human musculoskeletal research.