The Extensor Indicis is a muscle located in the forearm that plays a crucial role in extending the index finger. It originates from the posterior surface of the ulna and the interosseous membrane, and it inserts into the extensor expansion of the index finger. This muscle is innervated by the radial nerve, specifically the posterior interosseous branch. Functionally, the Extensor Indicis allows for precise movements of the index finger, enabling actions such as pointing and gripping. It works in conjunction with other muscles, including the extensor digitorum, to facilitate finger extension. This muscle is particularly important for tasks requiring fine motor skills.