Background: Nasal irrigation is an important component of medical management in chronic rhinosinusitis. Nasal irrigations facilitate topical medication of therapies and lavage of mucin. In this study we aim to compare the influence of increasing surgical sphenoid openings on the distribution, force, and clearance of nasal irrigations. Methods: A study was performed on fresh-frozen adult cadaver heads. The surgical ostium was modified on one side via a simple sphenoidotomy, a sphenoid sinusectomy (type 1), and sphenoid sinusectomy (type 3a). The nasal cavity was irrigated using a 240-mL squeeze bottle with 0.1% fluoroscein. An endoscope passed through the contralateral side through the sphenoid septum recorded the irrigation. Videos were recorded and blindly assessed. The distribution was defined as either no irrigation, less than one third of the sinus, less than or equal to two thirds of the sinus, or the complete sinus. The force was defined as minimal, minor, or major. The clearance was defined as no residual, less than one third of volume, less than or equal to two thirds of volume, and more than two thirds volume. Ordinal correlation scores were assessed using the Kendall tau-B test. Results: Nine specimens (sphenoid sinuses) were assessed (44.4% female; age, 75.0 ± 12.7 years). The use of a sphenoid sinusectomy or larger produced better distribution (percent specimens with more than one third: 100% vs 59%, p < 0.01), more force (percent major: 83% vs 29%, p < 0.01), and better clearance (percent with one third or less remaining: 56% vs 18%, p < 0.01). Conclusion: Increasing sphenoid ostial size improves nasal irrigation penetration. We propose that greater sphenoid sinusectomy size allows for improved lavage and irrigation penetration. Complete removal of the anterior face appears to mitigate pooling of irrigation.