Complete extensor digitorum profundus complex: a deep hand extensor muscle to the medial four digits.

Area of Science:

• Anatomy
• Morphology
• Human Anatomy

Background:

• Anatomical variants in the posterior forearm and hand are common.
• Awareness of these variations is crucial for accurate diagnosis and treatment of hand conditions.

Observation:

• A rare deep hand extensor muscle variant was identified during routine anatomical dissection.
• This variant presented as a complete extensor digitorum profundus complex within the fourth extensor compartment.

Findings:

• The observed complex comprised two muscle bellies originating from the distal ulna and interosseous membrane.
• One belly mimicked the extensor indicis proprius, while the second bifurcated, with tendons inserting into the index, middle, ring, and little fingers.

Implications:

• This is the first reported case of a complete extensor digitorum profundus complex with such extensive digital insertion in humans.
• Understanding such anatomical anomalies is vital for surgeons performing forearm and hand procedures.
• The case offers insights into the evolutionary and developmental pathways of forearm and hand musculature.