The transversus abdominus muscle is primarily innervated by which of the following nerves?

The transversus abdominus muscle, which is a key muscle of the abdominal wall, is primarily responsible for providing stability to the trunk and assisting in the compression of the abdominal cavity. Its innervation mainly comes from the intercostal nerves, particularly the lower thoracic intercostal nerves (T7-T11) and the subcostal nerve (T12). These nerves directly innervate the muscle and facilitate its function.

The other nerves listed are not responsible for the innervation of the transversus abdominus. The phrenic nerve primarily innervates the diaphragm and is crucial for respiratory functions. The femoral nerve mainly innervates muscles in the thigh and the skin over the anterior thigh and part of the leg. The radial nerve is associated with the innervation of the muscles in the posterior compartment of the arm and forearm, and is not involved with the abdominal musculature. Thus, the intercostal nerves are correctly identified as the primary source of innervation for the transversus abdominus muscle.