A 27-year-old woman in the third trimester of her first pregnancy has been experiencing pain in the right hand for the past month. She often awakens with her hand feeling numb and then experiences disturbing paresthesias in the entire hand over the next several minutes, typically resolving after about 5 minutes. Her medical history is otherwise unremarkable. Examination reveals decreased sensory perception for pinprick over the lateral, palmar aspect of the hand, including the thumb, index finger, and middle finger. There is no weakness and deep tendon reflexes are normal. Which of the following structures is the most likely site of neurologic dysfunction?

A. brachial plexus
B. cervical 6 nerve root
C. median nerve
D. radial nerve
E. ulnar nerve