The phrase 'περὶ κρατὶ σῷ βρύοντα' presents a syntactic crux regarding the governing preposition and the case of the participle. While 'βρύοντα' is the accusative singular masculine participle of 'βρύω' (to bubble/foam over), the preposition 'περί' here governs the dative 'κρατί' (head) rather than the expected accusative or genitive for a standard locative or circumstantial sense. This construction, where 'περί' + dative indicates the sphere or area in which the action of the participle occurs (i.e., 'foaming around the head'), is rare in Aristophanes and contrasts with the more common accusative usage for physical contact or surrounding. The dative 'κρατί' is also a metrical variant of 'κεφαλή' or 'κεφαλή' in poetic diction, but here specifically functions as the dative of 'κέφαλα' (head) in a context describing the physical state of Dionysus (or the character addressed) as overwhelmed by wine or fear, requiring the reader to parse the prepositional phrase not as a simple spatial boundary but as an encompassing condition affecting the subject.