Lymphatic Drainage of
Mouth and Pharynx
Lymphatic fluid, carried by the lymphatic
capillaries in the tissues of the mouth and pharynx, is all eventually taken by
the lymphatic vessels, either directly or with the interruption by interposed
lymph nodes, to the chain of lymph nodes lying along the internal
jugular vein. The efferent vessels from these nodes enter into the
formation of the jugular lymphatic trunk, which, characteristically, on
the left side empties into the thoracic duct near its termination and on
the right side into the right lymphatic duct. The thoracic duct and the
right lymphatic duct pour their lymph into the bloodstream at the junction of
the internal jugular and subclavian veins on the respective side.
On either side the jugular trunk may empty directly into the veins near this
site.
A more specific description of the
lymph nodes involved in the lymphatic drainage of the mouth and pharynx is
necessary because of their importance in the metastasis of cancer and the
significance attached to the enlargement of a node when an infection occurs in
its area of drainage. However, any specific description of lymph nodes is
complicated by the facts that lymphatics are quite variable and are difficult
or impossible to see in dissection when they are not pathologically conspicuous
and that the grouping of the nodes is at best arbitrary and, to quite an
extent, artificial. Because of this, descriptions of lymphatics vary greatly,
and many different names have been employed for individual nodes and groups of
nodes. The number of groups of nodes described for any region can, of course,
differ, depending on whether certain nodes are interpreted as forming a
separate group or are considered as subsidiaries of another group.
The grouping of the nodes of the head
and neck can be described briefly as follows: A pericervical collar of
nodes is located at the general region of the junction of the head and neck.
From the midline posteriorly to the midline anteriorly, the groups encountered,
in order, are occipital, mastoid, parotid, submandibular, and submental
nodes. A group of nodes superficial to the sternocleidomastoid muscle and
in close relation to the external jugular vein is called the superficial
cervical group of nodes; however, some consider them to be an extension of
the parotid group. The majority of the groups of nodes not included in the
“collar” just described run more or less vertically in the neck. Minor chains
of nodes lie along the anterior jugular vein and the spinal accessory
nerve, and a major chain of nodes accompanies the internal jugular vein
along its entire length. The latter is most commonly designated as the deep
cervical group of nodes and is often divided into superior deep cervical
nodes superior to the point at which the omohyoid muscle crosses the
internal jugular vein and the inferior deep cervical nodes inferior to
this point. The retropharyngeal nodes may be an expansion of the
superior portion of the superior deep cervical group or a separate group of
nodes located between the superolateral part of the pharynx and the
prevertebral fascia. Individual nodes are encountered constantly enough in two
locations in the superior deep cervical chain that they have merited special
naming. A jugulodigastric node is located between the angle of the
mandible and the anterior border of the sternocleidomastoid muscle, at about
the level of the greater horn of the hyoid bone and between the posterior belly
of the digastric muscle and the internal jugular vein. This node receives lymph
from the area of the palatine tonsil, tongue, and teeth. A juguloomohyoid
node, usually considered as the lowest node of the superior deep cervical
group, lies immediately superior to the intermediate tendon or the inferior
belly of the omohyoid muscle and may project beyond the posterior border of the
sternocleidomastoid muscle. This node receives some vessels directly from the
tongue in addition to its other afferents. A subparotid node just
inferior to the parotid gland is specially named by some authors. The inferior
deep cervical nodes, also called supraclavicular nodes, extend into the
posterior triangle of the neck, send expansions along the trans- verse cervical
and transverse scapular veins, and inter-mingle with the subclavian and apical
axillary lymph nodes. In addition to the groups of nodes described above,
some scattered nodes, part of which are often called anterior deep cervical
nodes, pertain to the larynx, trachea, esophagus, and thyroid gland.
The groups of
nodes specifically involved
in the drainage of lymph from
specific portions of the mouth and pharynx are indicated briefly in the
following statements: The lips have cutaneous and mucosal plexuses from which
the lymph drains to the submandibular, submental, and (to a slight extent)
superficial cervical groups. Lymph from the central part of the lower lip first
drains to the submental nodes. Lymph from the cheek travels mostly to the
submandibular nodes but also to superficial cervical nodes and, in part,
directly to superior deep cervical nodes. From the anterior part of the floor
of the mouth, drainage is, in part, directly to the lower of the superior deep
cervical group and, in part, to the submental and submandibular nodes. The
posterior part drains to submandibular and superior deep cervical nodes. Lymph
from the hard and soft palates may travel directly to superior deep cervical
nodes (near the digastric muscle) or to submandibular nodes or, particularly
from the soft palate, to retropharyngeal nodes. The lymphatics of the teeth
anastomose with those of the gums. Lymph from the superomedial alveolar
processes drains similarly to the palate, whereas lymph from the inferomedial
alveolar processes drains similarly to the floor of the mouth. Drainage from
the lateral alveolar processes is similar to that of the lips and cheek. The
jugulodigastric node, or at least a node in that area, may be enlarged when a
tooth, particularly in the molar region, is infected. The lymphatic drainage of
the tongue goes either directly or indirectly to the superior deep cervical
nodes, and, in general, the farther forward the area on the tongue, the lower
in the deep cervical chain is the related node. Four sets of collecting vessels
of the tongue are described: apical vessels lead to submental nodes and
the juguloomohyoid node; marginal vessels to superior deep cervical
nodes and perhaps submandibular nodes; basal vessels to superior deep
cervical nodes (chiefly, the jugulodigastric node); and central vessels mostly
to superior deep cervical nodes, with a few to submandibular nodes. The central
vessels from each side of the tongue go to both right and left superior deep
cervical nodes. No vessels from the tongue are said to reach any of the more
superficial nodes. Drainage from the large salivary glands is much as would be
expected: parotid gland to parotid nodes (some of which are described as being
in the substance of the gland); submandibular gland, in part to submandibular
nodes but mostly to superior deep cervical nodes; and sublingual gland, much
like that of the submandibular gland. Part of the lymph from the area of the
palatine tonsil goes to the superior deep cervical nodes and much of it to the
jugulodigastric node. The mucosa of the pharynx is rich in lymphatics, and the
drainage from the roof and upper part of the posterior wall is to the
retropharyngeal nodes. The collecting vessels of the laryngeal pharynx gather
in the wall of the piriform sinus, pierce the thyrohyoid membrane, and continue
to nearby superior deep cervical nodes.
