Which pronation movement is affected due to anterior division brachial plexus injury?

The anterior division of the brachial plexus primarily innervates muscles that are responsible for flexion and pronation of the forearm. An injury to this area can lead to weakened ability to perform pronation because the primary muscle responsible for pronation, the pronator teres, as well as the pronator quadratus, may be affected. These muscles are innervated by branches from the median nerve, which arises from the anterior division of the brachial plexus.

When there is an injury to this area, the motor function of the median nerve can be impaired, resulting in weakened pronation strength. The ability to fully pronate or achieve strong pronation is compromised, reflecting the muscle weakness caused by the nerve injury. This results in a diminished capacity to perform movements that require strong pronation, such as turning a door handle or performing certain manual tasks. Therefore, the answer indicating weak forearm pronation accurately describes the impact of an anterior division brachial plexus injury on pronation movements.