Anomalous Extensor Indicis Proprius Muscle Extending Beyond the Extensor Retinaculum: A Case Report

Area of Science:

• Anatomical studies
• Human anatomy
• Surgical anatomy

Background:

• The extensor indicis proprius (EIP) is a key muscle in the forearm.
• It is frequently utilized in tendon transfer surgeries, particularly for extensor pollicis longus ruptures.
• Understanding its normal anatomy is crucial for surgical success.

Observation:

• During a cadaveric dissection for anatomy education, an unusual variant of the extensor indicis proprius (EIP) muscle was identified.
• The muscle belly of this EIP variant extended distally, past the extensor retinaculum.
• This anatomical variation extends beyond previously documented descriptions in the literature.

Findings:

• A distinct anatomical variation of the extensor indicis proprius (EIP) muscle was observed.
• The EIP muscle belly demonstrated an atypical distal extension beyond the extensor retinaculum.
• This represents a rare deviation from the typical EIP anatomy.

Implications:

• Anatomical variants of the EIP muscle can impact the success of tendon transfer procedures.
• Such variations may lead to misdiagnosis of wrist masses if not recognized.
• Awareness of EIP variants is essential for accurate clinical diagnosis and surgical planning.