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Anatomic Levels of the Neck and Selective Neck Dissection

last modified on: Mon, 08/07/2023 - 08:20

return to: Cervical Lymphadenectomy- General Considerations

see also: Thoracic Duct and Chylothorax: General ConsiderationsMarginal Mandibular Nerve Weakness (Ramus Mandibularis) Level I Neck Dissection (extended) recurrent pleomorphic adenomaMyositis Ossificans of the Neck Surgical Treatment Heterotopic Bone Formation After Trauma


  1. Indications
    1. Elective treatment of N0 neck with significant risk of regional metastasis. See Cervical Lymphadenectomy- General Considerations protocol of selected N+ neck dissection
    2. Serves as a staging procedure and can be used for decision making regarding the need for adjuvant postoperative radiation therapy
    3. In selected groups of patients with N+ disease, the use of selective neck dissection (SND) is gaining support. When indicated, application of postoperative radiation therapy reduces the rate of regional failure.
    4. Recent reports have further diminished the extent of selective neck dissections to include 'nidusectomy' or removal of only the abnormal metastastic residual after chemo-radiotherapy (Hashmi 2022; Bertlich 2022)
  2. Contraindications
    1. Extensive neck disease.
    2. Evidence of extracapsular spread by clinical or radiographic evaluation (ie, fixed nodes, involvement of deep neck muscles, cranial nerves, sternocleidomastoid muscle, internal jugular vein, carotid artery (would require more radical dissection than a 'selective neck dissection'))
  3. Extent of Neck Dissection
    1. The selection of which levels of lymph nodes require removal depends on the location of the primary tumor and the predicted spread of local disease to regional sites.
  4. Historical Perspective
    1. The radical neck dissection was first described in 1906 by Crile, based on the Halstedian concept of en bloc resection. The purpose was to effectively remove all of the lymph nodes present in the neck and their interconnecting lymphatics. It was the standard of care for the following 70 years. However, in addition to nodes and lymphatics, it also removes the SCM (sternocleidomastoid), submandibular gland, tail of the parotid gland, internal and external jugular veins, cervical sensory nerves and cranial nerve 11. Suarez later realized that cervical lymphatics are contained within fascial spaces, consisting of the fascia covering the submandibular glands, carotid sheath, SCM and deep cervical muscles and nerves, and he incorporated this fact into his neck dissections. In 1967, Ferlito, as well as Bocca and Pignataro, coined the term "functional neck dissection," describing procedures that remove all the lymphatics but preseve non-lymphatic-containing structures. We now refer to this as a "modified neck dissection." Further advancements have demonstrated that depending on the situation, not all levels must be explored, thus, developing the concept of the "selective neck dissection."
  5. Anatomical Considerations
    1. Levels of the neck:
      1. Level Ia: Submental triangle
        1. Boundaries: Anterior belly of the digastric muscle and the hyoid bone
      2. Level Ib: Submandibular triangle
        1. Boundaries: Body of the mandible and the anterior and posterior bellies of the digastric muscle
      3. Level II: Upper jugular nodes
        1. Boundaries:
          1. Anterior: border of the stylohyoid muscle
          2. Posterior: posterior border of the sternocleidomastoid muscle
          3. Superior: skull base
          4. Inferior: Level of the hyoid bone (clinical), carotid bifurcation (surgical)
          5. *Level II is divided by the accessory nerve into levels IIa (anteriorly) and IIB (posteriorly).
      4. Level III: Middle jugular nodes
        1. Boundaries:
          1. Anterior: lateral border of the sternohyoid muscle.
          2. Posterior: posterior border of the sternocleidomastoid muscle
          3. Superior: hyoid bone
          4. Inferior: cricoid notch (clinical), omohyoid muscle (surgical)
      5. Level IV: Lower jugular nodes
        1. Boundaries:
          1. Anterior: lateral border of the sternohyoid muscle.
          2. Posterior: posterior border of the sternocleidomastoid muscle
          3. Superior: cricoid notch (clinical), omohyoid muscle (surgical)
          4. Inferior: clavicle
      6. Level V: Posterior triangle
        1. Boundaries:
          1. Anterior: posterior border of the sternocleidomastoid muscle
          2. Posterior: anterior border of the trapezius muscle
          3. Inferior: clavicle
        2. Level V was subdivided into level VA (superiorly) and VB (inferiorly)
          1. Levels VA and VB are separated by a horizontal plane marking the inferior border of the anterior cricoid arch 
            1. VA: spinal accessory lymph nodes
            2. VB: transverse cervical nodes and supraclavicular nodes (with exception of the Virchow node, in level IV)
      7. Level VI: Nodes of the anterior compartment - pretracheal, paratracheal, precricoid lymph nodes
        1. Boundaries:
          1. Lateral: lateral border of the sternohyoid muscle
          2. Superior: hyoid bone
          3. Inferior: suprasternal notch
      8. The Spinal Accessory nerve (see: Posterolateral neck dissection variant of trapezius innervation)
        1. The spinal accessory nerve is derived from motor neurons found in the spinal nucleus, extending down to the level of C5.
        2. This nerve enters the skull through the foramen magnum, only to finally exit the skull via the jugular foramen. It usually emerges posterior and lateral to the internal jugular vein, however 30% of the time it exits medial to the IJ, whereas 3-5% of the time it actually splits the vein and courses through the vessel. It then pierces the deep portion of the sternocleidomastoid muscle at approximately the level of the lateral process of C2, to then exit the posterior portion of the sternocleidomastoid, traversing the posterior triangle, where it then disappears under the anterior surface of the trapezius to innervate this muscle. Between the jugular vein and the sternocleidomastoid muscle, the accessory nerve overlies the transverse process of C1, along with the occipital artery.
        3. Innervation: This nerve innervates the sternocleidomastoid and trapezius muscles.
        4. The great auricular, transverse cervical and lesser occipital nerves emerge from the prevertebral fascia and travel anteriorly, superiorly, and inferiorly from a point along the posterior border of the sternocleidomastoid. The spinal accessory nerve can be identified approximately 1 cm superior to this point.
          1. The emergence of the nerves is sometimes erroneously referred to as Erb's point. Wilhelm Erb (1840-1921) was the father of modern electromyography, and identified a surface point at which the brachial plexus could be transcutaneously stimulated. This point is located several centimeters inferior to the point of emergence of the sensory cervical plexus nerves (Tubbs et al., 2007).
        5. This accessory nerve can also be found entering the anterior portion of the trapezius muscle approximately 5 cm above the clavicle.


  1. Additional Preoperative Evaluations
    1. CT with contrast or MRI or ultrasound of neck
    2. PET scan in most cases
    3. Fine needle aspiration of enlarged lymph nodes to confirm pathologic diagnosis and necessity of procedure
  2. Consent Inclusions
    1. See Radical neck dissection protocol


  1. Same as for radical neck dissection (see Radical neck dissection)


  1. Same as for radical neck dissection (see Radical neck dissection)


  1. Pertinent Anatomy
    1. Identify the angle and body of the mandible, mastoid tip, midline of neck, clavicle, and sternocleidomastoid muscle (SCM)
  2. Incisions
    1. Utility incision from mastoid tip into a transverse lower neck skin crease is used most commonly. A posterior limb may be dropped if access to Level IV is difficult.
    2. My personal bias (HTH): do not curve the incision up to the mastoid tip. Direct the posterior aspect of the incision in a horizontal fashion back to the trapezius muscle. If further exposure is needed, then a small vertical extension superiorly and/or inferiorly along the trapezius muscle will enhance exposure. Rationale: any limb that is used to extend an incision with a vertical component to the mastoid tip is located over the carotid artery and also places the tip of the flap at risk by diminishing its blood supply.
  3. Skin Flap Elevation
    1. Standard subplatysmal flap elevation leaving superficial veins and fascia of the SCM muscle down. The great auricular nerve may be preserved. If a tracheotomy has been performed, every attempt is made to keep the neck dissection separate from the tracheotomy site. If communication between the neck dissection and tracheotomy site occurs, it is closed in an airtight fashion to prevent an air leak from the suction drains.
    2. Limits of elevation
      1. Superior limit is mandible, mastoid tip, and parotid gland
      2. Inferior limit is clavicle
      3. Anterior limit is sternohyoid muscle
      4. Posterior limit is SCM
  4. Dissection
    1. Submandibular and submental dissection (Level I)
      1. If perifacial lymph nodes do not require removal, the superior skin flap is raised to the inferior aspect of the submandibular gland. The fascia over the gland is incised, and the posterior facial vein is ligated and divided. Both are elevated off the gland. This maneuver protects the marginal mandibular nerve from injury. The fascia is elevated to the inferior border of the mandible, and its attachments to the mandible are divided. The facial artery and vein are ligated and divided.
      2. The contralateral anterior belly of the digastric muscle is defined, and the superficial fat over the anterior bellies of both digastric muscles (submental fat) is dissected in a lateral direction. The dissection is continued laterally over the ipsilateral mylohyoid muscle, which is then retracted with an Army-Navy retractor anterosuperiorly. The submandibular gland is then retracted inferiorly. The submandibular fat and lymph nodes may be swept inferiorly with a sponge. The lingual nerve and submandibular ganglion are identified. The submandibular ganglion and duct are ligated and divided. The contents of the submandibular triangle are dissected in a medial to lateral direction. The facial artery is divided a second time at the posterior aspect of the gland. The specimen is rolled off the posterior belly of the digastric muscle and kept pedicled to the Level II neck contents.
      3. If the perifacial lymph nodes require removal, the superior subplatysmal flap is carefully raised with cold blunt or sharp dissection. The marginal mandibular branch of the facial nerve can be identified running just below the angle of the mandible proximal and superficial to the posterior facial vein and within the submandibular fascia in its middle portion before turning superiorly to the lower lip. The facial nerve stimulator may be used to help identify and confirm the integrity of the marginal mandibular nerve. Communicate with the anesthesia team that paralysis should be avoided after the neck dissection is begun. Once identified, the nerve is carefully elevated off the underlying soft tissue with the subplatysmal flap. The remaining portion of the dissection proceeds as described above.
    2. Jugular chain dissection (Levels II-IV)
      1. The fascia over the SCM is divided along its length. The fascia is elevated in a medial direction using a #15 blade scalpel or electrocautery. This dissection is facilitated by having an assistant retract the medial aspect of the incised fascia with Allis clamps or digital pressure employing a sponge. The surgeon can apply counter-traction on the muscle using a sponge in one hand while dissecting with a #15 blade in the other hand.
      2. The spinal accessory nerve is identified posterolateral to the internal jugular vein and into the medial aspect of the SCM muscle. The spinal accessory nerve is skeletonized from the surrounding soft tissue from the skull base to the SCM. If Level IIB (supraspinal compartment) is to be removed, the fatty tissue deep to the superior portion of the SCM muscle and overlying the deep neck musculature is sharply divided off the deep neck musculature fascial "carpet" and pulled under the spinal accessory nerve. In this manner, Level IIB remains in continuity with the remaining neck specimen. The occipital artery is usually encountered and ligated during this dissection.
      3. Once the SCM fascia has been elevated off the medial aspect of the muscle, the fascia and fat posterior to the internal jugular vein can be divided down the deep neck muscular fascial carpet. Arbitrarily establishing the posterior limit of Levels II, III, and IV as 2 cm posterior to the internal jugular vein ensures that the dissection is adequate to remove all of these levels (and some of Level V). The cervical rootlets are skeletonized as the fat and fascia are dissected anteriorly toward the internal jugular vein.
      4. The specimen is elevated superior to the fascial carpet using a #15 blade, sparing the cervical rootlets (preserving sensory to neck), brachial plexus, and phrenic nerve. Medial retraction of the specimen by an assistant is helpful in accomplishing this task. As the specimen is rolled out medially, the vagus nerve and carotid artery are identified first and preserved. The specimen is then sharply divided off the internal jugular vein just superficial to the adventitia. The omohyoid muscle is usually preserved, but may be sacrificed if exposure of Level IV is difficult.
      5. The specimen is then dissected away from the sternohyoid muscles inferiorly and off the hypoglossal nerve, branches of the internal jugular vein, and external carotid artery superiorly.
      6. If free tissue transfer is required for reconstruction of a primary defect, the internal jugular vein branches and external carotid artery branches should be handled with extreme care to avoid intimal damage. Ligation of these vessels should be performed as distal as possible to optimize vascular pedicle geometry.
      7. Following removal of the specimen, Level IV is inspected for a chyle leak. This is particularly important in a left neck dissection. Positive airway pressure applied by the anesthesiologist may aid in detection of a chyle leak (see: Chyle leak). If a leak is detected, it is carefully ligated with a 3-0 silk suture. Closure of the leak must be ensured prior to closure of the neck. Suture ligating or placement of vessel clips on all soft tissue while dissecting across the inferior extent of level IV can also be performed to prevent chyle leaks.
      8. The neck specimen is then divided into its component levels (ie, I, IIA, IIB, III, IV) on a back table and sent to pathology in separate containers.
  5. Closure
    1. Skin flaps are closed in 2 layers
      1. Platysma/subcutaneous layer with 3-0 vicryl
      2. Skin with surgical clips, 4-0 or 5-0 nylon
  6. Drains
    1. Several options are possible
    2. One option: two fully perforated, 10 mm Jackson-Pratt drains are placed
      1. Deep to the SCM and posterior to the internal jugular vein and spinal accessory nerve
      2. Anteriorly over the SCM into Level I
      3. Drains are attached to "grenade" suction bulbs or Varidyne pumps set for continuous suction at 125 cm H2O. Suction is initiated immediately following drain placement to prevent clotting of the drain while closing the skin.
  7. Dressing
    1. Bacitracin ointment to skin incision


  1. Same as for modified radical neck dissection (see Modified radical neck dissection protocol)


Same as for radical neck dissection (see Radical neck dissection protocol)

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Medina JE, Weisman RA. Management of the neck in head and neck cancer, part I. Otolaryngol Clin North Am. August 1998;585-686.

Medina JE, Weisman RA. Management of the neck in head and neck cancer, part II. Otolaryngol Clin North Am. October 1998;759-856.

Myers EN. Operative Otolaryngology Head and Neck Surgery, Chapter 78, Neck Dissection. Vol 1. 2nd Edition. Elsevier; 2008:679-708.

Medina JE. Chapter 113: Neck Dissection. In: Bailey BJ and Johnson JT. Head & Neck Surgery-Otolaryngology. 2. 4th ed. Lippincoott Williams & Wilkins; 2006:1585-1609.

Crile G.  Excision of cancer of the head and neck with special reference to the plan of dissection based on one hundred and thirty-two operations. JAMA 22:1780-1786, 1906.

Ferltio A, Rinaldo A.  Osvaldo Suarez: often-forgotten father of functional neck dissections (in the non-Spanish-speaking literature). Laryngoscope 11:1177-1178, 2004

Bocca E, Pignataro A.  A conservation technique in radical neck dissection. Ann Otol Surg 81:975-987, 1967.

Medina JE. A rational classification of neck dissections.  Otolaryngol Head Neck Surg 100:169-176, 1989.

Robbins KT, Clayman G, Levine PA; et al. Neck dissection classification update: revisions proposed by the American Head and Neck Society and the American Academy of Otolaryngology--Head and Neck Surgery. Arch Otolaryngol Head Neck Surg 2002;128(7):751-758.Tubbs RS, Loukas M, Salter EG, Oakes WJ. Wilhelm Erb and Erb's point. Clin Anat 2007 Jul;20(5);486-8.

Scott H. Saffold, MD; Mark K. Wax, MD; Anthony Nguyen, MD; James E. Caro, MD; Peter E. Andersen, MD; Edwin C. Everts, MD; James I. Cohen, MD, PhD. Sensory Changes Associated With Selective Neck Dissection; Arch Otolaryngol Head Neck Surg. 2000;126:425-428

Hashmi SS, Abbas A, Bukhari A, Saeed J, Shafqat A, Siddique AH, Buksh AR, Murtaza G. Selective Neck Dissection for Node-Positive Oral Cavity Squamous Cell Carcinoma: A Retrospective Cohort Study. Int Arch Otorhinolaryngol. 2022 Feb 22;26(4):e630-e635. doi: 10.1055/s-0041-1741437. PMID: 36405475; PMCID: PMC9668421.

Bertlich M, Zeller N, Freytag S, Spiegel JL, Weiss BG, Canis M, Haubner F, Ihler F. Factors influencing outcomes in selective neck dissection in 661 patients with head and neck squamous cell carcinoma. BMC Surg. 2022 May 19;22(1):196. doi: 10.1186/s12893-022-01644-6. PMID: 35590282; PMCID: PMC9118639.