Closing the Hole

Question:   A 43 year old woman presents with a history significant for recent vision loss and headache.  She undergoes workup with your neurology colleagues and is ultimately diagnosed with a large sellar tumor.  With the assistance of your neurosurgical colleague, you proceed with endonasal resection.  At the conclusion of the procedure, there is a large skull base defect and a spinal fluid leak.  You elect to use a multilayered technique for closure, and elevate a mucosal flap along the nasal septum and floor which you use to swing over the defect, providing vascularized tissue.  What is the arterial supply for this flap? [Answer will be posted with next week's new question]

Answer to last week's question, Not Just a Birthmark (Apr 27, 2015): 

Airway infantile hemangioma, involving the subglottis.