The document discusses the "Rule of 4" method for understanding brainstem anatomy, which notes that there are 4 structures in the midline beginning with M, 4 motor nuclei in the midline that are divisors of 12, 4 structures on the side beginning with S, and 4 cranial nerves in each region - medulla, pons, and above the pons. It then provides examples applying this rule to analyze lesions based on their associated symptoms.