Patients with neck pain can have pain in the fingers with difficulty in finger extension (finger straightening).
Extension of the finger joints (proximal and distal interphalangeal joints) is performed by the lumbricals and interossei muscles.
Extension of the knuckle joints (metacarpophalangeal joints) is performed by the extensor digitorum. If the knuckle joints are hyperextended, the extensor digitorum is unable to extend the finger joints.
In such a situation, extension of the finger joints is primarily through the action of the interossei and lumbrical muscles. However if the knuckle joints are flexed, the extensor digitorum aids the action of the interossei and lumbrical muscles in extending the finger joints.
Nerve supply:
- first and second lumbrical muscles: median nerve (C8, T1)
- third and fourth lumbrical muscles: deep branch of ulnar nerve (C8, T1)
- palmar and dorsal interossei muscles: deep branch of ulnar nerve (C8, T1)
- extensor digitorum: posterior interosseous nerve (C7, C8)