Posterior interosseous nerve

Posterior interosseous nerve (PIN) is a nerve in the human body that is a branch of the radial nerve. It is responsible for the extension of the fingers and the wrist, as well as the supination of the forearm.

Etymology

The term "interosseous" comes from the Latin words "inter", meaning "between", and "osseus", meaning "bony". This refers to the nerve's location between the two bones of the forearm, the radius and the ulna.

Anatomy

The posterior interosseous nerve originates from the radial nerve, which itself is a branch of the brachial plexus. The PIN travels down the forearm, passing through the supinator muscle before dividing into several smaller branches. These branches innervate the extensor muscles of the forearm, including the extensor carpi ulnaris, the extensor digitorum, and the extensor pollicis longus.

Clinical significance

Damage to the posterior interosseous nerve can result in a condition known as Posterior interosseous syndrome (PIS). This condition is characterized by the inability to extend the fingers and the wrist, as well as weakness in the supination of the forearm. PIS can be caused by a variety of factors, including direct trauma, compression from a tumor or cyst, or repetitive strain injury.

Related terms

• Radial nerve
• Brachial plexus
• Supinator muscle
• Extensor carpi ulnaris
• Extensor digitorum
• Extensor pollicis longus
• Posterior interosseous syndrome