Lymph Vessels of the Soft Palate and Tonsil
The lymph vessels from the rostral (oral) part of the soft palate, including the arcus glossopalatinus and the folds of the mucous membrane surrounding the tonsillar sinus, drain to both the dorsal mandibular and medial retropharyngeal lymph node groups, while those from the caudal (aboral) part of the soft palate drain only to the medial retropharyngeal lymph node.
The lymph vessels draining to the dorsal mandibular lymph node (Figure 14: 1’, 2’) run under the mucous membrane as far as the area of the last molar, joining with the corresponding lymph vessels from the back of the hard palate (see lymph vessels of the hard palate), and running with them under the M. masseter to drain to the dorsal mandibular lymph node. The small number of lymph vessels that drain to the ventral mandibular lymph nodes run along the medial side of the mandible, between the mucous membrane and the M. mylohyoideus ventrally and somewhat caudally, before penetrating the M. mylohyoideus and running to the ventral mandibular lymph nodes. The lymph vessels draining into the medial retropharyngeal lymph node (Figure 14: 1, 2) travel with the corresponding lymph vessels from the caudal part of the hard palate and those of the tonsil to the aforementioned lymph nodes (for details, see lymph vessels of the tonsils, below).
The lymph vessels of the tonsil drain to the medial retropharyngeal lymph node. Three to 5 lymph vessels leave the tonsil, emerging behind the palatoglossal arch (Figure 14: 3, 3), crossing the M. styloglossus medial to the M. digastricus by passing over either its lateral or medial surface, or passing through it, and then travelling along the pharyngeal muscles into the aforementioned lymph node. Some of the lymph vessels additionally run under the mucosal membrane of the lateral wall of the pharynx, proceeding to either penetrate the pharyngeal musculature, specifically (Figure 14) either the M. hyoglossus or the M. keratopharyngeus, or passing between the M. hyothyroideus (Figure 14: p), M. keratopharyngeus (Figure 14: m), and M. thyropharyngeus (Figure 14: n), before emerging (Figure 14: 4) and travelling along the pharyngeal muscles to drain to the medial retropharyngeal lymph node (Figure 14: u).
The lymph vessels of the mucosal fold surrounding the tonsillar sinus also drain to the medial retropharyngeal lymph node, however, a lymph vessel from just that portion of the fold facing away from the sinus may instead join with a corresponding soft palate lymph vessel to drain to the mandibular lymph nodes (Figure 14: 21).