1. A 36-year-old female is brought to the emergency room by her husband who says that she "complained of a severe headache then lost consciousness." She has a history of hypertension and had been on several different medications. The examining physician notes that she is unable to move her arms and legs, but can blink her eyes. When the physician asks her to blink twice if she can hear him, she promptly does so. In which of the following structures is this woman's lesion most likely located?