Delineation of the neck node levels for head and neck tumors: A 2013 update.

You can find the original guideline here¹.

Superficial (top) and deep (bottom) lymphatic node groups of the head and neck. These groups are named according to the node levels modified from Robbins
classification. AJ: anterior jugular; B: buccal; diP: deep intraparotid; F: facial; iH: infrahyoid; M: malar; Mt: mastoid; pA: preauricular; pL: prelaryngeal; pT: pretracheal; R: recurrent or paratracheal; sA: subauricular; SAN: spinal accessory nerve; SEJ: superficial external jugular; siP: superficial intraparotid; sMb: submandibular; sMt: submental; sP: subparotid; TCA: transverse cervical artery.

Comparison between the TNM atlas for lymph nodes in the neck and the guidelines of the lymph node levels modified from Robbins

Node levels and boundaries

Based on the information provided in the sources, here is a summary of the boundaries for each neck node level presented in a markdown table:

Node Level	Boundaries
Level Ia (Submental group)	Cranial: Mylo-hyoid muscle. Caudal: Platysma muscle (caudal edge of the anterior belly of digastric muscles). Anterior: Symphysis menti. Posterior: Body of hyoid bone/mylo-hyoid muscle. Lateral: Medial edge of anterior belly of digastric muscle. Medial: Not applicable (region is continuous with contralateral level Ia).
Level Ib (Submandibular group)	Cranial: Cranial edge of submandibular gland; anteriorly, mylo-hyoid muscle. Caudal: Plane through caudal edge of hyoid bone and caudal edge of mandible; alternatively, caudal edge of submandibular gland (whichever is more caudal)/platysma muscle. Anterior: Symphysis menti. Posterior: Posterior edge of submandibular gland (caudally)/posterior belly of digastric muscle (cranially). Lateral: Medial aspect (inner side) of mandible down to caudal edge/platysma muscle (caudal)/medial pterygoid muscle (posteriorly). Medial: Lateral edge of anterior belly of digastric muscle (caudally)/posterior belly of digastric muscle (cranially).
Level II (Upper jugular group)	Cranial: Caudal edge of the lateral process of C1. Caudal: Caudal edge of the body of the hyoid bone. Anterior: Posterior edge of the submandibular gland/posterior edge of posterior belly of digastric muscle. Posterior: Posterior edge of sternocleidomastoid muscle. Lateral: Deep (medial) surface of sternocleidomastoid muscle/platysma muscle/parotid gland/posterior belly of digastric muscle. Medial: Medial edge of internal carotid artery/scalenius muscle. Level II can be subdivided into level IIa and IIb by the posterior edge of the internal jugular vein.
Level III (Middle jugular group)	Cranial: Caudal edge of the body of the hyoid bone. Caudal: Caudal edge of cricoid cartilage. Anterior: Anterior edge of sternocleidomastoid muscle/posterior third of thyro-hyoid muscle. Posterior: Posterior edge of sternocleidomastoid muscle. Lateral: Deep (medial) surface of sternocleidomastoid muscle. Medial: Medial edge of common carotid artery/scalenius muscles.
Level IVa (Lower jugular group)	Cranial: Caudal edge of cricoid cartilage. Caudal: 2 cm cranial to sternal manubrium. Anterior: Anterior edge of sternocleidomastoid muscle (cranially)/body of sternocleidomastoid muscle (caudally). Posterior: Posterior edge of sternocleidomastoid muscle (cranially)/scalenius muscles (caudally). Lateral: Deep (medial) surface of sternocleidomastoid muscle (cranially)/lateral edge of sternocleidomastoid muscle (caudally). Medial: Medial edge of common carotid artery/lateral edge of thyroid gland/scalenius muscles (cranially)/medial edge of sternocleidomastoid muscle (caudally).
Level IVb (Medial supraclavicular group)	Cranial: Caudal border of level IVa (2 cm cranial to sternal manubrium). Caudal: Cranial edge of sternal manubrium. Anterior: Deep surface of sternocleidomastoid muscle/deep aspect of clavicle. Posterior: Anterior edge of scalenius muscles (cranially)/apex of lung, the brachiocephalic vein, the brachiocephalic trunk (right side) and the common carotid artery and subclavian artery on the left side (caudally). Lateral: Lateral edge of scalenius muscle. Medial: Lateral border of level VI (pre-tracheal component)/medial edge of common carotid artery.
Level V (Posterior triangle group)	Cranial: Cranial edge of the body of hyoid bone. Caudal: Plane just below transverse cervical vessels. Anterior: Posterior edge of sternocleidomastoid muscle. Posterior: Anterior border of trapezius muscle. Lateral: Platysma muscle/skin. Medial: Levator scapulae muscle/scalenius muscle (caudally). Surgically, Level V is subdivided into upper (Va) and lower (Vb) nodes according to their relationship with the cricoid cartilage. The caudal edge of the cricoid cartilage is used as an anatomic landmark to divide Va and Vb.
Level Vc (Lateral supraclavicular group)	Cranial: Plane just below transverse cervical vessels (caudal border of level V). Caudal: 2 cm cranial to sternal manubrium (caudal border of level IVa). Anterior: Skin. Posterior: Anterior border of trapezius muscle (cranially)/±1 cm anterior to serratus anterior muscle (caudally). Lateral: Trapezius muscle (cranially)/clavicle (caudally). Medial: Scalenius muscle/lateral edge of sternocleidomastoid muscle, lateral edge of level IVa.
Level VIa (Anterior jugular nodes)	Cranial: Caudal edge of the hyoid bone or caudal edge of the sub-mandibular gland, whichever is more caudal. For tumors of anterior floor of mouth, tip of tongue, lower lip, cranial limit is caudal edge of hyoid bone. Caudal: Cranial edge of the sternal manubrium. Anterior: Skin/platysma muscle. Posterior: Anterior aspect of the infrahyoid (strap) muscles. Lateral: Anterior edges of both sternocleidomastoid muscles. Medial: Not applicable. Level VIa is contained between the anterior edges of the sternocleidomastoid muscles.
Level VIb (Pre-laryngeal, pre-tracheal, para-tracheal nodes)	Cranial: Caudal edge of the thyroid cartilagea. For tumors of anterior floor of mouth, tip of tongue, lower lip, cranial limit is caudal edge of hyoid bone. Caudal: Cranial edge of the sternal manubrium. Anterior: Posterior aspect of infrahyoid (strap) muscles. Posterior: Anterior aspect of larynx, thyroid gland and trachea (pre-laryngeal and pre-tracheal nodes)/pre-vertebral muscle (right side)/esophagus (left side) (for para-tracheal nodes). Lateral: Common carotid artery on both sides. Medial: Lateral aspect of trachea & esophagus (caudally). Level VIb is contained between the 2 common carotid arteries.
Level VIIa (Retropharyngeal nodes)	Cranial: Upper edge of body of C1/hard palate. Caudal: Cranial edge of the body of the hyoid bone. Anterior: Posterior edge of the superior or middle pharyngeal constrictor muscle. Posterior: Longus capitis muscle and longus colli muscle. Lateral: Medial edge of the internal carotid artery. Medial: A line parallel to the lateral edge of the longus capiti muscle. Located within the retropharyngeal space. The lateral group lies medial to the internal carotid artery and lateral to a line parallel to the lateral edge of the longus capiti muscle. Only the lateral retropharyngeal nodes are considered in this proposal.
Level VIIb (Retro-styloid nodes)	Cranial: Base of skull (jugular foramen). Caudal: Caudal edge of the lateral process of C1 (upper limit of level II). Anterior: Posterior edge of prestyloid para-pharyngeal space. Posterior: Vertebral body of C1, base of skull. Lateral: Styloid process/deep parotid lobe. Medial: Medial edge of the internal carotid artery. These nodes are the cranial continuation of level II nodes, located in the fatty space around the jugulo-carotid vessels up to the base of the skull.
Level VIII (Parotid node group)	Cranial: Zygomatic arch, external auditory canal. Caudal: Angle of the mandible. Anterior: Posterior edge of mandibular ramus & posterior edge of masseter muscle (laterally), medial pterygoid muscle (medially). Posterior: Anterior edge of sternocleidomastoid muscle (laterally), posterior belly of digastric muscle (medially). Lateral: SMAS layer in subcutaneous tissue. Medial: Styloid process and styloid muscle. Includes subcutaneous pre-auricular, superficial and deep intraparotid, and subparotid nodes.
Level IX (Bucco-facial group)	Cranial: Caudal edge of the orbit. Caudal: Caudal edge of the mandible. Anterior: SMAS layer in subcutaneous tissue. Posterior: Anterior edge of masseter muscle & corpus adiposum buccae (Bichat’s fat pad). Lateral: SMAS layer in subcutaneous tissue. Medial: Buccinator muscle. Includes malar and bucco-facial nodes, often superficial nodes around the facial vessels.
Level Xa (Retroauricular nodes)	Cranial: Cranial edge of external auditory canal. Caudal: Tip of the mastoid. Anterior: Anterior edge of the mastoid (caudally)/posterior edge of the external auditory canal (cranially). Posterior: Anterior border of occipital nodes – posterior edge of sternocleidomastoid muscle. Lateral: Subcutaneous tissue. Medial: Splenius capitis muscle (caudally)/temporal bone (cranially). Also called mastoid and subauricular nodes.
Level Xb (Occipital nodes)	Cranial: External occipital protuberance. Caudal: Cranial border of level V. Anterior: Posterior edge of sternocleidomastoid muscle. Posterior: Anterior (lateral) edge of trapezius muscle. Lateral: Subcutaneous tissue. Medial: Splenius capitis muscle. These nodes are the cranial and superficial continuation of the level Va nodes.

The terms "cranial" and "caudal" refer to structures closer to the cephalic and pedal ends, respectively. "Anterior" and "posterior" are used instead of "ventral" and "dorsal". These boundaries are described for a patient lying supine with their head in a "neutral" position. While these guidelines provide detailed boundaries, clinical judgment is still necessary, especially in situations where anatomical landmarks may be altered, such as with neck skin folds or in the post-operative setting.

Node levels on CT sections

1: common carotid artery; 2: internal carotid artery; 3: external carotid artery; 4: internal jugular vein; 5: external jugular vein; 6: anterior jugular vein; 7: right brachiocephalic trunc; 8: right brachiocephalic vein; 9: left susclavian artery; 10: left susclavian vein; 11: facial vessels; 12: masseter m.; 13: pterygoid m.; 14: longus capitis m.; 15: longus colli m.; 16: sternocleidomastoid m.; 17: digastric (ant. belly) m.; 18: digastric (post. belly) m.; 19: platysma m. 20: trapezius m.; 21: splenius capitis m.; 22: scalenius m.; 23: levator scapulae m.; 24: serratus anterior m.; 25: thyro-hyoid m.; 26: sterno-hyoid m.; 27: parotid gland; 28: sub-mandibular gland; 29: thyroid gland; 30: mastoid; 31: styloid process; 32: mandible; 33: maxilla; 34: hyoid bone; 35: odontoid process; 36: 2nd cervical vertebra; 37: 4th cervical vertebra; 38: 6th cervical vertebra; 39: thyroid cartilage; 40: cricoid cartilage; 41: clavicle; 42: 1st thoracic vertebra; 43: 2nd thoracic vertebra; 44: rib; 45: lung apex; 46: esophagus; 47: Bichat’s fat pad; 48: pre-styloid para-pharyngeal space.

Main tumor sites at risk for harboring metastases in each defined neck node level

Neck Node Level	Main Tumor Sites at Risk
Level Ia (Submental group)	Floor of the mouth, the anterior oral tongue, the anterior mandibular alveolar ridge, and the lower lip. Also drain the skin of the chin, the mid-lower lip, the tip of the tongue, and the anterior floor of the mouth.
Level Ib (Submandibular group)	Cancers of the oral cavity, anterior nasal cavity, soft tissue structures of the mid-face, and the submandibular gland. Receive efferent lymphatics from the submental lymph nodes (level Ia), the lower nasal cavity, the hard and soft palate, the maxillary and mandibular alveolar ridges, the cheek, the upper and lower lips, and most of the anterior tongue.
Level II (Upper jugular group)	Cancers of the nasal cavity, oral cavity, nasopharynx, oropharynx, hypopharynx, larynx, and the major salivary glands. Level IIb is more likely associated with primary tumors of the oropharynx or nasopharynx, and less frequently with tumors of the oral cavity, larynx or hypopharynx. Receive efferent lymphatics from the face, the parotid gland, and the submandibular, submental and retropharyngeal nodes. Directly receive collecting lymphatics from the nasal cavity, the pharynx, the larynx, the external auditory canal, the middle ear, and the sublingual and submandibular glands.
Level III (Middle jugular group)	Cancers of the oral cavity, nasopharynx, oropharynx, hypopharynx and larynx. Collect lymphatics from the base of the tongue, tonsils, larynx, hypopharynx and thyroid gland. Receive efferent lymphatics from levels II and V, and some from retropharyngeal, pretracheal and recurrent laryngeal nodes.
Level IVa (Lower jugular group)	Cancers of the hypopharynx, larynx, thyroid and cervical esophagus. Rarely, metastases from the anterior oral cavity may manifest in this location with minimal or no proximal nodal disease. Receive efferent lymphatics primarily from levels III and V, some efferent lymphatics from the retropharyngeal, pretracheal, and recurrent laryngeal nodes, and collecting lymphatics from the hypopharynx, larynx, and thyroid gland.
Level IVb (Medial supraclavicular group)	Cancers of the hypopharynx, sub-glottic larynx, trachea, thyroid and cervical esophagus. Receive efferent lymphatics primarily from levels IVa and Vc, some efferent lymphatics from the pretracheal, and recurrent laryngeal nodes, and collecting lymphatics from the hypopharynx, esophagus, larynx, trachea and thyroid gland.
Level V (Posterior triangle group – Va and Vb)	Cancers of the nasopharynx, oropharynx and thyroid gland. Nodes in Level V are most often associated with primary cancers of the nasopharynx, the oropharynx, the cutaneous structures of the posterior scalp, and the thyroid gland (level Vb). Receive efferent lymphatics from the occipital and retroauricular nodes as well as those from the occipital and parietal scalp, the skin of the lateral and posterior neck and shoulder, the nasopharynx, the oropharynx and the thyroid gland.
Level Vc (Lateral supraclavicular group)	More commonly associated with nasopharyngeal tumors. Receive efferent lymphatics from the posterior triangle nodes (level Va and Vb).
Level VIa (Anterior jugular nodes)	Their treatment should only be addressed in lower lip tumors and in advanced gingivo-mandibular carcinomas invading the soft tissues of the chin. These nodes mostly drain the integuments of the lower face and anterior neck.
Level VIb (Pre-laryngeal, pre-tracheal, para-tracheal-recurrent laryngeal nerve nodes)	Cancers of the lower lip, the oral cavity (floor of mouth and tip of the tongue), the thyroid gland, the glottic and subglottic larynx, the apex of the piriform sinus, and the cervical esophagus. Receive efferent lymphatics from the anterior floor of mouth, the tip of the tongue, the lower lip, the thyroid gland, the glottic and subglottic larynx, the hypopharynx, and the cervical esophagus.
Level VIIa (Retropharyngeal nodes)	Cancers of the nasopharynx, the posterior pharyngeal wall and the oropharynx (mainly the tonsillar fossa and the soft palate). Receive efferent lymphatics from the mucosa of the nasopharynx, the Eustachian tube and the soft palate.
Level VIIb (Retro-styloid nodes)	Cancers of the nasopharynx, and from any other head and neck primary with massive infiltration of upper level II nodes through retrograde lymph flow. Receive efferent lymphatics from the nasopharyngeal mucosa.
Level VIII (Parotid node group)	Especially from tumors of the frontal and temporal skin, the orbit, the external auditory canal, the nasal cavities, and the parotid gland. Also at risk from cancers of the frontal and temporal skin, eyelids, conjunctiva, auricle, external acoustic meatus, tympanum, nasal cavities, root of the nose, nasopharynx, and Eustachian tube.
Level IX (Bucco-facial group)	Cancers of the skin of the face, the nose, the maxillary sinus (infiltrating the soft tissue of the cheek) and the buccal mucosa. Receive efferent vessels from the nose, the eyelids, and the cheek.
Level Xa (Retroauricular nodes)	Mainly from skin cancers of the retro-auricular area. Receive efferent vessels from the posterior surface of the auricle, the external auditory canal and the adjacent scalp.
Level Xb (Occipital nodes)	Skin cancers of the occipital area. Receive efferent vessels from the posterior part of the hair-bearing scalp.

1. Grégoire V, Ang K, Budach W, Grau C, Hamoir M, Langendijk JA, Lee A, Le QT, Maingon P, Nutting C, O’Sullivan B, Porceddu SV, Lengele B. Delineation of the neck node levels for head and neck tumors: a 2013 update. DAHANCA, EORTC, HKNPCSG, NCIC CTG, NCRI, RTOG, TROG consensus guidelines. Radiother Oncol. 2014 Jan;110(1):172-81. doi: 10.1016/j.radonc.2013.10.010. Epub 2013 Oct 31. PMID: 24183870. ↩