Anterior interosseous nerve: anatomical study and clinical implications.

Area of Science:

• Anatomy
• Neuroscience
• Orthopedics

Background:

• The anterior interosseous nerve (AIN) is crucial for motor function of the forearm and hand.
• Understanding its anatomical variations is key to diagnosing and treating AIN palsy.
• AIN palsy can result in significant functional deficits, impacting the distal phalanges of the thumb and index finger.

Purpose of the Study:

• To detail the anatomical variations of the anterior interosseous nerve.
• To explore the clinical implications of these variations, particularly in relation to nerve compression.
• To correlate anatomical findings with the presentation of anterior interosseous nerve palsy.

Main Methods:

• Dissection of 50 upper limbs from 25 cadavers (22 male, 3 female; age 28-77).
• Cadavers were prepared via intra-arterial injection or fresh dissection.
• Detailed anatomical measurements and observations of the AIN's origin and course were recorded.

Main Results:

• The AIN originated from the median nerve an average of 5.2 cm distal to the intercondylar line.
• Variations in origin from the median nerve fascicles (posterior vs. posterolateral) were noted in 29 and 21 limbs, respectively.
• AIN duplication occurred in two limbs; its position relative to the pronator teres and flexor digitorum superficialis arches was documented.

Conclusions:

• Fibrous arches of the pronator teres and flexor digitorum superficialis muscles can compress the AIN.
• Hypertrophy of the Gantzer muscle can also lead to AIN compression.
• These anatomical structures can alter the nerve's course, leading to symptoms of AIN palsy.