Levels IIa and IIb are separated by the vertical plane defined by the spinal accessory nerve Minor variations to the above anatomic boundaries have been described.įor example, head and neck surgeons may use different intraoperative landmarks 1,4: Includes anterior jugular, pretracheal, paratracheal, prelaryngeal/precricoid ( Delphian), and perithyroidal nodesĪll the levels above eventually drain to the jugular trunk of their respective side and then to the right lymphatic duct or the thoracic duct (left) 10. Laterally: medial borders of both common carotid arteries (medial to levels III and IV) Posteriorly: trachea (medially) and prevertebral space (laterally) 8 Inferiorly: superior border of manubrium (suprasternal notch) Superiorly: inferior border of hyoid bone Level Vb: inferior half, inferior to inferior border of the cricoid cartilage (posterior to level IV) includes lateral supraclavicular nodes 1 Level Va: superior half, superior to inferior border of the cricoid cartilage (posterior to levels II and III) includes spinal accessory nerve Posterolaterally: anterior border of the trapezius muscle Superiorly: skull base at the apex of the convergence of sternocleidomastoid and trapezius musclesĪnteromedially: posterior border of the sternocleidomastoid muscle Includes medial supraclavicular nodes including Virchow node 1 Medially: medial border of the common carotid artery Posterolaterally: oblique line drawn through the posterolateral edge of the sternocleidomastoid muscle and the lateral edge of the anterior scalene muscle 2 Superiorly: inferior border of the cricoid cartilage Level IV: lower internal jugular (deep cervical) chain Medially: medial border of the common carotid artery Inferiorly: inferior border of the cricoid cartilageĪnteriorly: anterior border of the sternocleidomastoid muscle Superiorly: inferior border of the hyoid bone Level III: middle internal jugular (deep cervical) chain Level IIb: posterior to and separable by a fat plane from the internal jugular vein Level IIa: inseparable from or anterior to the posterior edge of the internal jugular vein includes jugulodigastric nodal group Medially: medial border of the internal carotid artery Posterolaterally: posterior border of the sternocleidomastoid muscle Inferiorly: inferior border of the hyoid boneĪnteriorly: posterior border of the submandibular gland Superiorly: base of the skull at the jugular fossa Level II: upper internal jugular (deep cervical) chain Level Ib (submandibular nodes): posterolateral to the anterior belly of the digastric muscles Level Ia (submental nodes): anteromedial between the anterior bellies of both digastric muscles Posteriorly: posterior border of the submandibular gland Inferiorly: inferior border of the hyoid bone Superiorly: mylohyoid muscle and mandible The following is a synthesis of radiologically useful boundaries for each level. Differing definitions exist across specialties 1-4. The lymph nodes in the neck have historically been divided into at least six anatomic neck lymph node levels for the purpose of head and neck cancer staging and therapy planning.
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