Posterior Interosseous Nerve

Description

Schematic drawing (anterior view) of the proximal posterior interosseous nerve (deep branch of radial nerve) before its entrance into the supinator muscle

The course of the PIN in the proximal supinator canal. PIN is indicated by small arrows on the sagittal sonogram showing the proximal part of the supinator muscle (top). Comparison with a magnetic resonance (MR) image (bottom). The sagittal sonogram reveals a posterior interosseous nerve with normal diameter (indicated by the calipers in the sonograms, solid arrow on MR). The proximity of the recurrent radial vessels (dashed arrow) may lead to nerve irritation and may induce lateral elbow pain. In the axial MR image, the PIN is clearly visible in the proximal part of the supinator canal (solid arrow). Note the prominent radial vessels (dashed arrows).

Other Names

• Posterior Interosseous Nerve
• PIN
• Deep Branch of the Radial Nerve

General

• The PIN is a branch of the Radial Nerve
• Supplies the majority of muscles of the Posterior Compartment of the Forearm

Anatomic Course

• Originates as a continuation of the deep branch of the radial nerve as it passes through supinator
• Runs in a plane between the superficial and deep muscles of the posterior compartment
• When it reaches the wrist joint, it terminates
• Supplying sensory branches to the dorsal wrist

Sensory Function

• Supplies sensory fibers to the Wrist Joint
• It does not have any cutaneous innervation

Motor Functions

• Superficial Dorsal Compartment of the Forearm
  • Extensor Digitorum
  • Extensor Digiti Minimi
  • Extensor Carpi Ulnaris
  • Anconeus
• Deep Dorsal Compartment of the Forearm
  • Abductor Pollicis Longus
  • Extensor Pollicis Brevis
  • Extensor Pollicis Longus
  • Extensor Indicis
  • Supinator

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Clinical Significance

• Posterior Interosseous Nerve Syndrome

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See Also

• Neuropathies Main
• Forearm Pain Main
• Wrist Pain Main
• Physical Exam Wrist
• Hand and Wrist Anatomy Main

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