8-A837A-2017-Books-00129-029-060_Katz_Sec1_Ch02-ROUND-1

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should be based on the burden of disease in adjacent compartments. If, however, there is clinical evidence of disease at the time of surgery, dissection of these compartments should be included. A number of incisions can be utilized to approach the lateral compartment: some surgeons prefer a low-lying collar incision, while others utilize a vertical extension toward the angle of the jaw. Irrespective of the specific incision, the end point must allow for appropriate exposure to the lymph node compartments (Fig. 2-9). After the incision, subplatysmal flaps are made to maximize exposure to the operative field. The superior flap should extend to the hyoid bone, and the inferior flap should extend to the sternum (midline) and clavicle more laterally. Disruption of the sensory cervi- cal nerves, including the greater auricular nerve, may lead to numbness of the lateral neck and ear. Patients should be advised of this possibility before surgery. During the procedure, care should be taken in the retraction of the upper, or cranial, skin flap because the marginal mandibular branch of the facial nerve runs just below the man- dible and may be compressed by enthusiastic retraction. Once adequate exposure has been obtained, the anterior border of the SCM should be incised longitudinally along the anterior border to expose the plane between the SCM and the strap (sternohyoid and sternothyroid) muscles. This allows for identification of the underlying omohyoid muscle, which can be divided to further expose the carotid sheath (internal jugular vein [IJV], common carotid artery, and vagus nerve) posteriorly. The fascia along the posterior border of the SCM should also be incised to allow for full mobility of the muscle, which can be retracted with instruments or encircled with a Penrose drain. The SCM is rarely divided in a primary operation.

Platysma

Anterior jugular nodes

Anterior cervical fascia Strap muscles

Sternoclei- domastoid muscle Common carotid artery Internal jugular vein Omohyoid muscle (separated)

Sternoclei- domastoid muscle

FIGURE 2-9  Modified radical neck dissection incision, subplatysmal flaps, and dissection be- tween sternocleidomastoid muscle and strap muscles (left) . Initial dissection along lateral border of internal jugular vein above level of clavicle (right) .