Surface anatomy of the parotid duct and its clinical relevance

The trajectory of the parotid duct (PD) makes it vulnerable to injuries during facial trauma and facial rejuvenation procedures. The PD is usually represented as a straight line, although its description in the literature varies. Our objective was to study the trajectory of the PD and to define reliable cutaneous landmarks. We dissected 35 human cadaver half-heads. We defined three points: point I where the PD crossed a line (line 2) between point T (the intertragal incisura) and point C (the corner of the mouth), point S for the top of the PD, and point B where the PD penetrated the buccinator muscle. We measured the distance (D) between points T and C, the distance (d1) between points T and I, and the distance (d2) between points T and B. We also determined the height (h) of the orthogonal line between point S and line 2. We noted that for all of the half-heads that we examined, the PD followed a curved trajectory between points I and B above line 2. Point I was located 1/3 of the way along distance D. Point B was tangential to line 2, and was located 2/3 of the way along distance D. The average height measurement (h) was 1.4 cm. We demonstrated that the PD follows a curved trajectory from the 1/3 mark to the 2/3 mark along distance D, the top of this curve being 1.5 cm above the line TC.