Head and neck nodal anatomy is critically important. There have been a variety of revisions in the IMRT era to improve head and neck nodal identification. Most recently, in 2013, the Delineation of neck nodes levels was revised through a joint effort of the DAHANCA, EORTC, HKNPCSG, NCIC, CTG, NCRI, RTOG and TROG groups. Grégoire, Ang, et al published this in the Green Journal (Radiotherapy and Oncology 110(2014) 172-181). The original neck nodal descriptors were based on surgical anatomic landmarks, from which the original nomenclature derives. This has been revised and extended by the group twice, with a goal to reduce treatment variations between radiation centers.
The following nodal groups have been defined:
Submandibular Nodes: in the space between the inner side of the mandible, laterally and the digastric muscle medially, from the submandibular gland to the sympysis menti.
These nodes drain the following regions:
Level Ib nodes are at highest risk of metastases from cancers of the oral cavity, anterior nasal cavity, and soft tissues of the face and submandibular gland.
The Level II nodes are at risk of harboring disease from:
Middle jugular nodes which are the caudal extension of level II from the caudal edge of the hyoid bone to the caudal edge of the cricoid cartilage. The anterior border is the anterior edge of the sternocleidomastoid muscle or the posterior 1/3 of the thyro-hyoid muscle and the posterior edge of the sternocleidomastoid muscle. The lateral aspect is bounded by the medial surface of the sternocliedomastoid muscle. The medial edge is bounded by the medial edge of the common carotid artery and the scalene muscles.
The Level III nodes drain levels II and V and some of the retropharyngeal (Level 9 in the new parlance), pretracheal (Level 8), and recurrent laryngeal nodes.
The Level III nodes drain the following areas:
The Level III nodes are at risk of harboring metastases from:
Level IVa nodes contain the lower jugular nodes and extend distally from the lower limit of the level III nodes to 2 cm superior to the sternoclavicular joint. (Grégorie states that this is an arbitrary level, based on actual surgical dissection practices). The medial edge is the medial edge of the common carotid artery. The lateral edge is the medial surface of the sternocleidomastoid muscle.
Level IVa nodes drain level III and V, with some retropharyngeal and recurrent laryngeal drainage. Level IVa also drains collecting lymphatics from the hypopharynx, larynx and thyroid gland.
Level IVa nodes are at risk for metastases from the following:
Level IVb nodes continue the level IVa nodes to the cranial edge of the manubrium. The anterior border is the deep aspect of the sternocleidomastoid muscle, posterior limit is the scalene muscle, apex of lung, brachiocephalic vein, brachiocephalic artery (right neck), common carotid artery and subclavian artery (left neck). The lateral limit is the lateral edge of the scalene muscles. the medial limit is the medial edge of the common carotid artery.
The Level IVb nodes drain level IVa and Vc, some of the lymphatics from teh pretrachial and recurrent laryngeal nodes, hypopharyx, esophagus, larynx, tracha and thyroid gland.
Level IVb nodes are at risk from metastases from:
Posterior triangle group, located posterior to the sternocleidomastoid muscle. This group follows the spinal accessory nerve and extends from the plane crossing the cranial edge of the body of the hyoid to the cervical transverse vessels. The hyoid bone is the radiological landmark indentifying the superior aspect of the Level V nodes. The lateral limit is the platysma muscle, withe medial boundary by the levator scapulae and posterior scalene distally. The posterior aspect is the anterior surface of the trapezius muscles. Surgeons use the cricoid cartilage to further divide Level V into a/b sublevels.
This group receives from the occipital and retro-auricular nodes, the occipital and parietal scalp, skin of the lateral and posterior neck and shoulder, nasopharynx, oropharynx and thyroid gland. It also receives drainage from the nasopharynx, oropharynx and thyroid gland.
Level V nodes are at risk from metastases from cancers of:
Level Vc sublevel contains the lateral supraclavicular nodes contiguous and inferior to Level Va/b nodes in the posterior triangle. The inferior boundary is an arbitrary limit set 2 cm superior to the sternal manubrium. This region corresponds the the nodal region traditionally known as the supraclavicular fossa. The anterior limit is the skin, posterior limit is the anterior border of the trapezius muscle or about 1 cm from the anterior surface of the serratus anterior muscle. Medially, this group abuts level IVa and laterally is bounded by the clavical (distal) and trapezius (proximal).
Level Vc receives from the Level Va/b and is more commonly associated with nasopharyngeal tumors.
Level Vc is most commonly associated with tumors arising in the nasopharynx.
Contains the pre- and paratrachial nodes, recurrent laryngeal nodes, and is bounded by the anerior edges of the sternocleidomastoid muscle. It drains the glottic and subglottic larynx, oral cavity, apex of the pyriform sinus and cervical esophagus.
Level VI a/b nodes are at high risk for metastases from: