The lymph vessels of the gingivae have already been carefully examined by Schweitzer . Nevertheless, I injected them several times and was able to confirm almost all of Schweitzer’s findings. The results were as follows: most of the lymph vessels of the gingivae drain into the mandibular lymph nodes, though a smaller number drain into the medial retropharyngeal lymph node. The lymph vessels from the buccal, labial, and lingual sides of the upper and lower teeth (incisors and molars) all drain into the mandibular lymph nodes. Additionally, those from the lingual side of the teeth (incisors and molars) drain into the medial retropharyngeal lymph node. The lymph vessels from the gingivae on the lingual side of the upper teeth join the lymph vessels of the hard palate (see section D below).
A. Lymph Vessels of the Labial Side of the Maxillary Incisors, Molars, and Premolars
The lymph vessels of the gingivae on the labial side of the intermaxillary incisors and on the buccal side of the maxillary premolars and molars form an extremely dense, finely meshed lymphatic network in and under the mucous membrane, from which a large number of small lymph vessels emerge. These lymph vessels combine to form several (5 to 7) trunks, which initially run a distance quite deep in the lip and cheek mucosa, then penetrate through the cheek muscles at various points (Figure 13: 6), travelling with the lymph vessels of the upper lip and cheek mucosa to the oral border of the M. masseter. Almost all the lymph vessels then run over the lateral surface of the M. masseter to drain into the mandibular lymph nodes (Figure 13: 2, 2’, 2’’), most frequently to the dorsal group.
Occasionally, 1 to 2 of these lymph vessels drain into one of the ventral mandibular lymph nodes. This behaviour may not be as rare as described by Schweitzer: in 6 cases, I observed the behaviour twice. When the gingiva of the upper incisors in the median plane was punctured and injected, lymph vessels drained into the mandibular lymph nodes on both the left and right sides. However, lymph vessels additionally drained to both sides when puncture injection was done at the border of the 1st and 2nd upper incisors of only one side.
B. Lymph Vessels of the Labial Side of the Mandibular Incisors and Buccal Side of the Mandibular Premolars and Molars
The lymph vessels of the gingivae on the labial side of the mandibular incisors and on the buccal side of the mandibular premolars and molars form the same network in and under the mucous membrane as mentioned above, and these lymph vessels will eventually merge together to form 5 to 7 trunks. Some of these trunks pass through the ventral portion of the M. buccalis, while others emerge at its ventral margin (Figure 13: 7) and travel more or less to the incisura vasorum, running a fairly long distance in the intermandibular region. From the incisura vasorum, the lymph vessels then drain into the ventral mandibular lymph nodes (Figure 13: 2’, 2’’), and only rarely to the dorsal mandibular lymph node. If there are 2 ventral mandibular lymph nodes beside one another, the lymph vessels from the incisor region mostly flow into the aboral lymph node, and those from the molar region into the oral lymph node.
C. Lymph Vessels of the Lingual Side of the Mandibular Molars, Premolars, and Incisors
The lymph vessels of the gingivae on the lingual side of the mandibular molars, the mandibular premolars, and the mandibular incisors show three different patterns of drainage to the ventral mandibular lymph nodes and the medial retropharyngeal lymph node:
i. Some of the lymph vessels pass on the molar margin between 2 teeth to the lateral side, joining the lymph vessels from the gingivae on the lateral side of the molars (Figure 13: 7) and running with them to the ventral mandibular lymph nodes (Figure 13: 2’, 2’’). Rarely, one of these lymph vessels will also drain to a dorsal mandibular lymph node. This was observed for the gingivae of the molars.
ii. Other lymph vessels penetrate the M. mylohyoideus, reach its outer surface, and run in a caudal direction to the ventral mandibular lymph nodes, and along the pharyngeal muscles to the retropharyngeal lymph node.
iii. Finally, some of the lymph vessels run caudally on the medial side of the M. mylohyoideus. Of these vessels, some then run from the caudal border of this muscle along the pharyngeal muscles to drain into the retropharyngeal lymph node, and others descend along the medial side of the M. digastricus to drain into the ventral mandibular lymph nodes.
D. Lymph Vessels of the Lingual Side of the Upper Incisors, Premolars, and Molars
The lymph vessels of the gingivae on the lingual side of the upper incisors, premolars, and molars join those of the mucous membrane of the hard palate and accompany them to the mandibular lymph nodes and the medial retropharyngeal lymph node (see lymph vessels of the hard palate). Occasionally, a lymph vessel from the gingivae of the incisors and premolars will cross the median plane and enter the corresponding lymph nodes on the other side. Schweitzer has stated that there are always 3 mandibular lymph nodes present, one dorsal and two ventral, and that the regional drainage of the individual lymph nodes is sharply delineated insofar as the lymph vessels of the gingivae of the maxillary teeth (with the exception of 1 case) all drained to the dorsal node, while those of the gingivae of the mandibular teeth drained to the 2 ventral lymph nodes. I could not confirm this statement, because the number of lymph nodes in this group ranges from 2 to 5 (see mandibular lymph nodes), and also because, even when there were 3 mandibular lymph nodes, I found many cases that were exceptions to Schweitzer’s statement.