Final answer:
The extensor digitorum lateralis and the extensor digitorum communis extend the fingers and the hand at the wrist. They work in opposition to the flexor digitorum superficialis and flexor digitorum profundus, which flex the fingers and the hand at the wrist. This extension function is important for activities that require spreading or straightening the fingers.
Step-by-step explanation:
The action of the extensor digitorum lateralis, which is part of the dorsal group of the forearm, and one of the actions of extensor digitorum communis is to extend the fingers and the hand at the wrist. The extensor digitorum lateralis is specifically involved in extension of the digits (fingers), whereas the extensor digitorum communis also assists in this function. By contrast, the flexor digitorum superficialis and flexor digitorum profundus, which are located in the anterior compartment of the forearm, act to flex the fingers and the hand at the wrist.
The balance between these flexor and extensor muscles allows for the dexterous movements of the fingers and hand that are essential for daily activities. The extensor muscles increase the angle at joints of the fingers, contributing to the spread and straightening of the fingers, an action crucial for releasing objects, typing, and other precision tasks. Notably, muscles like the extensor carpi radialis longus perform additional actions such as extending and abducting the hand at the wrist, aiding in movements like those required to manipulate a computer mouse or to perform a backhand stroke in tennis.