Cervical spine compression tests for evaluation of the IVFs were within normal limits. Grip test of the right hand was normal when the elbow was flexed but when the arm was down at his side, grip strength was diminished by 10 pounds.  

X-rays of the cervical spine were ordered for this patient, and the results were consistent with normal findings.

Question: With compression tests and X-ray evaluation both showing normal findings, what other structures would you consider for further evaluation of this patient?