The lingual artery is distributed in base of tongue and mobile tongue and susceptible damage during operation. Such injury can lead to immediate or delayed hemorrhage, which can be life threatening. If both lingual arteries are damaged, necrosis of mobile tongue below damaged point is inevitable. Knowledge of anatomical distribution of the lingual artery is crucial during surgery such as partial glossectomy or tongue base surgery to reduce complications. It is also helpful to decide resection margin and reconstruction.

The lingual artery originates from the external carotid artery just above the superior thyroid artery and runs into the intrinsic muscle of tongue through the posterior border of the hyoglossus muscle. The lingual artery gives first branch, dorsal lingual artery, while passing the hyoglossus muscle. It proceeds anterosuperiorly and gives sublingual artery at the anterior border of hyoglossus muscle. After giving sublingual artery, the lingual artery shifts to deep lingual artery. Deep lingual artery runs through inferior portion of mobile tongue giving multiple perforating branches toward dorsum of the tongue. The lingual artery can be subdivided into 4 segments. The first segment is original segment which starts from hyoid bone to the point where dorsal lingual artery is given. The 2nd part, hyoglossus segment and the 3rd part, ascending segment is divided where the sublingual artery originates. Deep lingual artery is designated as horizontal segment [1].

There were several previous studies to analyze the course of the lingual artery and the anatomical markers. Hou et al. [2,3] used computed tomographic angiography to analyze anatomic relationship between the lingual artery and lingual markers and to set safety space for functional surgery on the tongue. Kimura et al. [4] used Doppler sonography to evaluate the lingual artery at the midpoint of tongue. Lopez et al. [5] studied about vascular territory of the lingual artery using selective ink injections in 15 fresh cadaver heads. But none of these studies researched histologic features of the lingual artery on mobile tongue. In this study, we made 18 healthy cadaveric tongues into 8 coronal sections each to clarify the anatomical distribution of the lingual artery in normal Korean subjects by light microscopic observation.

Oral cavity is limited space so only a small amount of bleeding can disturb surgical fields. Tongue has excellent mobility and abundant vasculatures. Massive bleeding can occur when main trunk of the lingual artery is damaged and ligation is difficult due to limited surgical field [6,7]. Thus, it is important to prevent excessive bleeding by preserving the lingual artery. In this study, we used eighteen cadaveric tongues to clarify anatomical distribution of the lingual artery by light microscopic observation.

There were a few studies about anatomical distributions of the lingual artery using computed tomographic angiography, Doppler sonography and cadaveric tongue [2-5,8]. Hou et al. [2] analyzed the lingual artery to define safety space for functional surgery of the tongue using computed tomographic angiography. He proposed V-zone of the tongue which is similar with our findings [2], but most of the reports focused on base of tongue and lack an explicit description of the lingual artery morphology and topography at the level of the tongue.

We tried to define useful surgical markers to facilitating a surgeon’s ability to avoid intraoperative lingual artery injury. We used median raphe, foramen cecum, tongue tip, and dorsal surface of the tongue as anatomical markers because they were relatively constant at any position. We measured the length of the dorsal surface of the tongue from tongue tip to foramen cecum then divided it into 8 coronal sections and produced histopathologic slides. D of the lingual artery from the dorsal surface of the tongue is gradually increased until the lingual artery reaches 75% of length of tongue from tongue tip. From there, D of the lingual artery remains stable to foramen cecum. D of the lingual artery varies with the position of the tongue, so measured value itself cannot be used in surgical fields which require traction into multidirections. Operator should keep in mind that the lingual artery located deeper pathway vertically from the surface as it reaches tongue base. The lingual artery runs lateral direction until three-fourths of tongue length. LD of the lingual artery from median raphe varies with the position of the tongue, too. P remains constant during forward traction of the tongue so it is helpful in surgical fields. The lingual artery is located within 50% of transverse length of tongue from median raphe. Surgical resection that does not exceed the ranges mentioned above is relatively safe. If the tumor extends more than a half of transverse length from lateral border in one side, the risk of the lingual artery damage increases. The area between lingual arteries is relatively safe. The mean LD at foramen cecum are 11.0±4.8 mm in the right side and 12.2±5.9 mm in the left side. This is consistent with Hou et al. [2]’s findings that surgery performed within approximately 15 mm of the tongue midline is relatively safe. Both sides of the lingual artery run symmetric and there is no transseptal anastomosis between sides like Houseman et al. [9]’s findings. However, the limitation of this study is that tissue shrinkage can occur during formalin fixation and microscopic slide production. The degree of shrinkage can differ according to contractility of the tissue. Tongue tissue can shrink due to intrinsic muscle’s contraction [10].

In conclusion, the lingual arteries of both sides are symmetric and run toward inferior and lateral directions from tongue tip to 75% of total length, but there is no significant difference around base of tongue. Finally the lingual artery located within 50% of transverse length of tongue from midline raphe. Lingual artery is usually sacrificed during resection of lesion involving tongue base. Distal injury of the lingual artery can be salvaged but proximal injury cause disaster in half portion of the mobile tongue. These findings provide surgeons useful information to set safe surgical margin that does not compromise function of the tongue during oral and base of tongue related surgery. The results of present study are notable because this is the first research to evaluate the histologic features of lingual artery on mobile tongue.