Clinical anatomy of the equine sphenopalatine sinus.
Authors: McCann J L, Dixon P M, Mayhew I G
Journal: Equine veterinary journal
Summary
# Editorial Summary: Clinical anatomy of the equine sphenopalatine sinus McCann, Dixon and Mayhew (2004) examined the anatomical relationships of the sphenopalatine sinuses in 16 equidae using transverse skull sections, prompted by clinical reports of empyema and neoplasia in these sinuses causing cranial nerve damage without clear understanding of the underlying anatomy. Significant individual variation emerged across the population: sphenoidal sinuses were small in younger horses and enlarged progressively with age, the septum between left and right sinuses was frequently deviated from midline, and the extent of sinus extension into the basisphenoid bone varied considerably. The sphenoidal and palatine sinuses communicated in most cases, typically draining into the caudal maxillary sinuses, though 31% of specimens also demonstrated drainage into the ethmoidal sinus. Critically, the thin dorsal and lateral walls of the sphenoidal sinus lay directly adjacent to cranial nerves II, III, IV, V and VI alongside major blood vessels—a proximity that explains the variable and potentially severe neurological signs, haemorrhage and septic complications observed clinically when sinus disease occurs. This anatomical variability between individual horses underscores why sphenopalatine sinus pathology can present with unpredictable clinical manifestations, emphasising the importance of detailed imaging and careful surgical planning when managing these cases.
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Practical Takeaways
- •Disorders affecting the sphenopalatine sinuses can cause unpredictable neurological signs due to close proximity to multiple cranial nerves—clinical presentation will vary between horses
- •Age-related changes in sinus size and complexity mean that sinus conditions in young versus mature horses may present differently and require consideration of developmental anatomy
- •The thin sinus walls mean significant hemorrhage and rapid spread of infection into surrounding structures are serious risks; early diagnosis and treatment of sphenopalatine sinus disease is critical
Key Findings
- •Sphenoidal sinuses are small in young horses and become larger and more complex with age
- •Significant anatomical variation exists between individual horses in sphenopalatine sinus extent and septum position
- •The dorsal and lateral walls of the sphenoidal sinus are extremely thin and directly adjacent to cranial nerves II, III, IV, V, and VI and major blood vessels
- •Sphenoidal and palatine sinuses communicate in most horses, typically draining into caudal maxillary sinuses, with 5 of 16 cases also draining into ethmoidal sinus