Lateral Congenital Anomalies of the Pharyngeal Apparatus: Part III. Cadaveric Representation of the Course of Second and Third Cleft and Pouch Fistulas

Abstract

"Stepladder" surgery for fistula from second or third pharyngeal cleft and pouch is "blind." Neither intraoperative methylene blue injection and probing nor preoperative imaging (fistulogram ultrasound, computed tomography, magnetic resonance imaging) reveal three-dimensional anatomic relations of fistulas. This article describes the most common second and third fistula courses and demonstrates representation of their tracts with wires in human cadavers. A second cleft and pouch fistula, at its external opening, pierces superficial cervical fascia (and platysma), then investing cervical fascia, and travels under the sternocleidomastoid muscle, superficial to the sternohyoid and anterior belly of omohyoid. It ascends along the carotid sheath, and at the upper border of the thyroid cartilage it pierces the pretracheal fascia. Characteristically, it courses between the carotid bifurcation and over the hypoglossal nerve. After passing beneath the posterior belly of the digastric muscle and the stylohyoid, it hooks around both glossopharyngeal nerve and stylopharyngeus muscle. The fistula reaches the pharynx below the superior constrictor muscle. The course of a third cleft and pouch fistula is similar until it has pierced pretracheal fascia; then it passes over the hypoglossal nerve and behind the internal carotid, finally descending parallel to the superior laryngeal nerve, reaching the thyrohyoid membrane cranial to the nerve.