Dorsal Interossei

The Dorsal Interossei are muscles of the hand.

Anatomical Attachments:

• Origin: There are four dorsal interossei that attach to the two heads from the adjacent sides of the metacarpal bones.
• Insertion: Attach to the base of the proximal phalanges to the extensor expansion of the 2nd, 3rd, and 4th digits.

Action: Draw the index, middle and ring fingers from the midline of the hand.

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Nerve Supply: Ulnar nerve (C8, T1).

Nerve Entrapment: Entraps digital nerves that cause cutaneous hypoesthesia along the side of the finger that is affected.

Vascular supply: Deep volar arch artery.

• Primary: The pain refers to the radial side of the index finger and deeply into the dorsum and through the palm of the hand; it may also extend along the dorsal and ulnar side of the index finger. Myofascial TrPs in the remaining dorsal and palmar interossei refer pain along the side of the finger that it attaches to.
• Satellite or associated triggers: Intrinsic thumb muscles, Long flexors and extensors of the fingers, Latissimus Dorsi, Pectoralis major, Scalene, Lateral or medial head of the Triceps brachii.

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Trigger Point Signs and Symptoms: Pain or stiffness of the fingers, impairment of hand motion and tenderness of the joints.

Trigger Point Activating and Perpetuating Factors: Repetitive pincer grasp, knitting, coloring, drawing or writing for long periods of time.

Differential Diagnosis: (Segmental, Subluxation, Somatic dysfunction) C6 or C7 radiculopathy, Ulnar neuropathy, C8 or T1 radiculopathy, Thoracic outlet syndrome, Carpal tunnel syndrome, De Quervain’s stenosing tenosynovitis, Carpometacarpal dysfunction, Osteoarthritis, Articular Dysfunction, Bone cancer, Bone fracture, Paronychia (Ingrown fingernail), Strain/Sprain, Rheumatoid Arthritis, Dupuytren’s Contracture, Ganglion cyst, Mixed Connective Tissue Disease, Raynaud’s Phenomenon, Frostbite, Diabetic Neuropathy, Systemic infections or inflammation, Nutritional inadequacy, Metabolic imbalance, Toxicity, Side effects of medication.

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