1. Palmar Interossei

Origin: Ulnar side of 2nd metacarpal, radial side of metacarpals 4 and 5

Insertion:

• 1st – ulnar base of the proximal phalanx/extensor expansion of digit 2
• 2nd and 3rd – Radial base of proximal phalanges/extensor expansion of digits 4-5

Action: Adduct the fingers towards midline

Innervation: Deep branch of the ulnar nerve (C8/T1)

Needling

Position: Various (sitting, supine, prone) with arm supinated

Palpation: Palpate between the metacarpals

Technique: Needle between the metacarpals using the medial aspect of the metacarpal 2, 4, and 5 as a bony backdrop

Caution: Low – interdigital nerves vulnerable when needling these muscles