Anatomical Course and Location
The parotid duct is the excretory pathway of the parotid gland (glandula parotidea). Its facial topography features several key landmarks:
- Direction — The duct runs horizontally, parallel to the zygomatic arch and 1.5–2.0 cm inferior to it.
- Relation to fascia and muscles — The duct courses across the superficial surface of the masseter muscle (m. masseter). In this segment, it lies within the splitting of the parotido-masseteric fascia (fascia parotideomasseterica) before continuing into the subcutaneous tissue.
- Penetration into the oral cavity — The duct pierces the buccinator muscle (m. buccinator), which presses the cheek against the teeth.
- Opening — The duct opens into the oral vestibule (vestibulum oris) via the parotid papilla (papilla parotidea). The orifice is located on the buccal mucosa at the level of the upper second molar or between the first and second upper molars.
Accompanying Structures
On the superficial surface of the masseter muscle (m. masseter), the parotid duct is accompanied by structures traveling in a parallel transverse direction:
- Transverse facial artery and vein (a. et v. transversa faciei).
- Buccal branches of the facial nerve (rr. buccales n. facialis).
Clinical Significance and Diagnostics
- Palpation — The excretory duct of the parotid gland can be palpated on the face as a firm cord running parallel to and 1–2 cm below the zygomatic arch.
- Mumps (Epidemic Parotitis) — Parotid gland involvement may lead to decreased salivation (hyposalivation), dry mouth, and thirst. A specific local sign of the infection is Mury's sign — edema and hyperemia of the parotid duct orifice (ductus parotideus) on the buccal mucosa on the affected side.
- Surgical Approaches — When draining abscesses in the parotid region via external incisions, only the skin and subcutaneous tissue are incised sharply, while deeper layers are dissected bluntly to avoid injuring the branches of the facial nerve.
Surgical Repair of Duct Injuries
Surgical management is indicated for injuries or fistulae of the parotid duct. For complete fistulae, plastic reconstruction to restore physiological salivary drainage is the preferred approach.
Plastic reconstruction (Vasiliev technique) includes the following steps:
- Isolation of the duct — Mobilization of the injured segment.
- Flap creation — A tongue-shaped mucosal flap is harvested from the buccal mucosa with its base directed anteriorly.
- Flap transposition — The created flap is passed through a specially created vertical incision. The anterior border of the masseter muscle (m. masseter) serves as the topographical landmark for this incision.
- Anastomosis — The tongue-shaped flap is sutured directly to the isolated parotid duct to re-establish the salivary outflow tract.
- Closure — Final closure of the surgical wound.
Alternatively, en-bloc excision of the fistulous tract along with the specific lobule of the salivary gland connected to the fistula may be performed.