A 55-year old male presents for evaluation of a lesion on his lower lip for the past year. He is employed as a landscaper and repos infrequent use of sun protection. He denies any peinent medical history. Physical examination reveals a 5 mm erythematous, ulcerative nodule located within the vermilion of the right lateral aspect of the lower lip. Biopsy confirms the presence of invasive squamous cell carcinoma and the patient is referred for Mohs micrographic surgical excision. Which of the following lymph nodes would be most critical to evaluate for metastasis?