What are the different levels of lymph nodes in the neck and which areas do they drain?

Neck Lymph Node Levels and Drainage Patterns

Anatomic Classification of Neck Levels

The neck is divided into 10 distinct lymph node groups, with levels I-VI representing the primary lateral and central compartments that drain specific head and neck subsites. 1

Level I (Submental and Submandibular)

• Level Ia (Submental): Bounded by the anterior belly of digastric muscles laterally and hyoid bone inferiorly 1
• Level Ib (Submandibular): Contains submandibular gland and nodes, bounded by anterior and posterior bellies of digastric muscle 1
• Drains: Anterior oral cavity, anterior tongue, floor of mouth, lower lip 2

Level II (Upper Jugular)

• Level IIa: Anterior to spinal accessory nerve 1
• Level IIb: Posterior to spinal accessory nerve, separated by a fat plane 1
• Drains: Oral cavity, oropharynx, nasopharynx, hypopharynx, larynx - essentially all head and neck mucosal sites 2, 1

Level III (Middle Jugular)

• Extends from hyoid bone superiorly to cricoid cartilage (or omohyoid muscle crossing) inferiorly 1
• Drains: Oral cavity, oropharynx, hypopharynx, larynx 2

Level IV (Lower Jugular)

• Extends from cricoid cartilage to clavicle 1
• Drains: Hypopharynx, larynx (especially subglottic), thyroid, cervical esophagus 2

Level V (Posterior Triangle)

• Level Va: Superior to cricoid cartilage 1
• Level Vb: Inferior to cricoid cartilage (supraclavicular fossa) 1
• Drains: Nasopharynx, thyroid, posterior scalp, skin of posterior neck 2, 1
• Critical pitfall: 50% of masses in supraclavicular fossa arise from primaries below the clavicle, requiring thorough evaluation for distant primary sites 2

Level VI (Central Compartment)

• Level VIa: Prelaryngeal, intercricothyroidal, pretracheal, and perithyroidal nodes between hyoid bone and cricoid cartilage 3
• Level VIb: Inferior laryngeal nodes between cricoid cartilage and suprasternal notch 3
• Drains: Thyroid gland, larynx (especially glottic and subglottic), hypopharynx, cervical esophagus, trachea 3, 4
• Distribution: 67% of level VI lymph nodes are in the pretracheal sublevel 4

Level VII (Superior Mediastinal)

• Nodes inferior to suprasternal notch, should not be confused with level VI 3

Retropharyngeal Nodes

• Located between pharyngeal mucosa and prevertebral fascia 1
• Drains: Nasopharynx, oropharynx, hypopharynx 5, 1

Site-Specific Drainage Patterns

Oral Cavity

• Primary drainage: Levels I-III ipsilaterally 2
• Midline/anterior tongue lesions: Require bilateral submandibular dissection and contralateral assessment due to bilateral drainage risk 2

Oropharynx, Hypopharynx, Larynx

• Primary drainage: Levels II-IV bilaterally 2
• Infraglottic laryngeal cancers: Must include level VI, as this is frequently involved 6, 2

Nasopharynx

• Primary drainage: Retropharyngeal nodes and levels II-V bilaterally 7, 2
• Level Ib: May be omitted unless anterior nasal cavity involved, or level II nodes show extracapsular extension, size >2 cm, or bilateral involvement 7, 5

Thyroid

• Primary drainage: Level VI (central compartment) and level V 2

Critical Clinical Pitfalls

Never omit level VI for infraglottic laryngeal cancers - this level is frequently involved and omission leads to inadequate treatment 6, 2

Never perform unilateral dissection for midline tumors (base of tongue, palate, supraglottic larynx) - bilateral drainage mandates bilateral treatment 6, 2

Floor of mouth tumors may not visualize sentinel nodes due to shine-through effect from close proximity to injection site, and metastatic blockage can prevent sentinel node visualization 2

Include at least one level below involved nodes in selective neck dissection to account for skip metastases 2

Level Ib inclusion criteria: Include ipsilateral level Ib if structures drain to Ib as first echelon, with submandibular gland involvement, or with ipsilateral level IIA nodes showing extracapsular extension 2