This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Head & Neck, Subject name: Anatomy
Choose the appropriate lettered structure in this MRI scan showing a sagittal section through the head and neck. A lesion of the first cervical spinal nerve would cause functional impairment of which structure? 
Select and explain. 
A. A, B. B, C. C, D. D
C: C
Answer: C: C 
Explanation: (c) The geniohyoid muscle is innervated by the first cervical nerve through the hypoglossal nerve.