The deltoid branch (ramus deltoideus) is one of the branches of the brachial plexus. It arises from the lateral trunk of the brachial plexus and innervates the deltoid muscle.
The deltoid branch branches at the level of the inferior border of the deltoid muscle. It passes through this muscle, giving it motor branches.
The deltoid branch provides motor innervation to the deltoid muscle, which abducts, adducts, and rotates the shoulder. Damage to the deltoid branch leads to paralysis of the deltoid muscle and impaired movement in the shoulder joint.