Lymphatic Anatomy

The supraclavicular chain of nodes, known also as the “transverse chain,” is located along the transverse cervical artery (TCA) ( Fig. 15.1 ). It receives afferent vessels from the anterolateral neck skin, chest wall, mammary gland, and occasionally from the upper extremity and the infraclavicular nodes. Anterior tributaries connecting the superficial anterior cervical nodes are located in the anterior jugular pathway, draining lymph from the skin and muscles of the infrahyoid region, the isthmus of the thyroid gland, and the infraglottic part of the larynx. Tributaries arise laterally from the accessory lymphatic chain and channels from the superficial external jugular nodes.

The supraclavicular chain of nodes, known also as the “transverse chain,” is located along the transverse cervical artery.

The majority of the lymphatic pathways from the breast toward the supraclavicular region are indirect. The infraclavicular (apical) nodes, typically terminating in the scalene nodes posterior to the sternocleidomastoid (SCM) and clavicle, may drain to the supraclavicular nodes. An “axillary bypass” directly into these nodes may be present in 5–17% of cases.

Efferent lymphatics (typically two to three) form the supraclavicular trunk, which enters the subclavian venous angle either directly or via the thoracic duct (or the right lymphatic duct).

In the left neck, the last node intercalated within the thoracic duct after its ascendance in the chest is referred to as Virchow’s node. It is located at or near the jugulo-subclavian venous junction (also referred to as the venous angle). Lymphadenopathy in the region may be a clinical harbinger of the metastatic disease from an abdominal source (particularly from the stomach). This is thought to be due to lymph reflux and trapping of malignant cells from the terminal thoracic duct. Due to its location, this node is not included in the dissection, which is performed at a more superficial plane.

From a clinical standpoint, the American Joint Committee on Cancer and the American Academy of Otolaryngology–Head and Neck Surgery define level V lymph nodes as the posterior triangle group. This includes the supraclavicular lymph nodes. In 2002, amendments were made to this classification suggesting a subdivision of level V into level Va and level Vb. By this designation, level Va nodes are located posterior to the SCM muscle, above the horizontal plane defined by the inferior border of the cricoid cartilage, including nodes along the spinal accessory nerve. Level Vb nodes are located posterior to the SCM, caudal to the horizontal plane made by the inferior border of the cricoid cartilage. This group includes the lymph nodes situated along the TCA, previously designated by some authors as a separate, “supraclavicular” group, not including level V. These nodes, of the supraclavicular triangle, are the targets of harvest in this flap’s design.

Terminological clarification is important in understanding the role of these nodes in lymphatic metastases and their relative expendability, as evidenced by their physiologically inconsequential harvest in cervical lymph node dissections for oncological purposes. The supraclavicular lymph nodes play a role in the drainage of structures of the head and neck as exemplified in studies tracking metastases of head and neck tumors such as papillary thyroid cancer. Current understanding suggests a stepwise progression of lymphatic metastases, rendering level Vb nodes a reasonable target from an oncological perspective, as their involvement in head and neck cancers is relatively low. Head and neck lymph drainage is site specific and occurs in a predictable fashion. In a paper by Mukherji in 2001, the frequency of supraclavicular nodal involvement in an array of head and neck cancers was surveyed, based on the classic reports of Lindberg and Byers. The frequencies reported were as follows: 11% in nasopharyngeal carcinoma, 1% floor of mouth carcinoma, 4% base of tongue carcinoma, 3% in supraglottic, and none in oral tongue, tonsillar, and soft palate cancers. For these reasons, level Vb node dissection is not commonly performed in cervical lymph node dissection for staging and curative intents and is reserved for lateral tumors closer to this region. Similar frequencies are reported in papillary carcinomas of the thyroid, where levels II, III, and IV are more commonly involved.

Using melanoma lymphoscintigraphy data to understand the functional anatomy of the lymphatics draining the skin, the supraclavicular basin appears to play a role in skin drainage of the lateral neck and jawline, albeit secondary to nodes of levels II and IV. The supraclavicular cluster does not appear to play a role in drainage of upper extremities (which drain to the various axillary nodes, and subsequently to the subclavian trunk).

Vascular Anatomy

Cordova et al. reported on their vascular investigation of the supraclavicular region in 2009. The TCA emanates from the thyrocervical trunk, posterior to the SCM muscle. The vasculature is relatively constant, with the TCA commonly originating from the thyrocervical trunk (80%), directly from the subclavian artery (17%), or as a branch of the internal mammary artery in a small minority of cases. The TCA courses posterolaterally approximately 2 cm above the clavicle toward the trapezius, deep to the inferior belly of the omohyoid. The TCA gives off a superficial and a deep branch. An average of four perforators to the supraclavicular skin arise from the superficial branch of the TCA (majority of cases); to a lesser degree directly from the TCA; and occasionally from the deep, terminal branch of the TCA. Mixed variants may exist. A separate supraclavicular branch of the TCA runs a lateral course superior to the clavicle, supplying the skin flap ( Fig. 15.2 ).

The transverse cervical artery gives off perforators to the supraclavicular skin, supplying the skin flap.

Venous tributaries accompanying the TCA perforators coalesce into one or two vena comitantes of the TCA, draining ultimately into the transverse cervical vein (TCV). A separate, superficial venous system appears to be the main venous outflow, draining into the external jugular vein (EJV) via the superficial cervical vein. The deep system (i.e., the venae comitantes of the TCA) serves a secondary role in drainage. This observation is the rationale for incorporating superficial veins (typically the EJV) to serve as the venous drainage for the transferred flap. Venous perforators consistently accompany the arterial ones. Although the superficial cervical vein tributaries consistently drain into the EJV, connections between the vena comitantes and the EJV are not always present.

The length of the pedicle ranges between 3 and 6 cm. The arterial diameter is between 1.5 and 2.5 mm, with the EJV usually greater than 3.0 mm or TCV ranging between 2.0 and 3.0 mm in diameter.