Muscle Name: first dorsal interosseous
AKA:
Abbreviation: FDI
Spinal Nerve Roots:
C8
T1
Brachial Plexus Trunks:
lower trunk
Brachial Plexus Cords:
medial cord
Named Nerves:
ulnar nerve
Proximal Attachment: metacarpal bone.
Distal Attachment: proximal phalanx on the first digit.
Action: Abduct the first digit.
Needle Insertion: With the hand in the midpoint between supination and pronation, the needline is inserted at the midpoint between the first and second metacarpal bone.
Activation for EMG: Abduct the finger. ("Point to the ceiling")
Pitfalls:
Notes: One of the least painful hand muscles to study.