Selective Neck Dissection - Vula - University of Cape Town

shoulder due to mechanical stimulation ofthe nerve (Figure 23).a scalpel (Figure 24). This exposes structuresdeep to the SCM i.e. the remainder ofLevels II and III of the neck and the lateralsurface of the omohyoid muscle as itcrosses the internal jugular vein. A numberof small vessels entering the muscle areencountered and cauterized. The dissectionis carried posteriorly along the deep aspectof the muscle in a subepimysial plane up tothe posterior edge of the SCM.ArteryFigure 22: SCM branch of occipital arterytethering the XIInFigure 24: Dissect along the anteriorborder of the sternomastoid in asubepimysial plane taking care not toinjure the XIn where it enters the muscleFigure 23: Dividing the SCM branch of theoccipital artery frees the XIIn that thenleads directly to IJV. Note the XIn and thetunnel created behind IJVStep 4 (Figure 7)ECAXIInIJVTunnelXInDissect with a scalpel or electrocauteryalong the omohyoid and strip the fattytissue in the anterior parts of Levels II andIII from the underlying infrahyoid strapmuscles in a posterior direction towardsthe carotid sheath.Divide the epimysium along the anteriorborder of the SCM using electrocautery orStep 5 (Figure 7)Attention is now directed to clearing LevelIIb which is located posterior to the IJVand deep to SCM. Opinions differ as towhether Level IIb (posterior to XIn) needsto be routinely dissected so as to minimisetrauma to the XIn.The upper part of the SCM is retractedposteriorly to expose Level IIb. With ahaemostat, create a tunnel immediatelyposterior to the IJV down to theprevertebral muscles (Figure 23). Thismanoeuver speeds up the subsequentdissection of Level IIb by clearlydelineating the posterior wall of the IJV.The transverse process of the C1 vertebracan be palpated immediately posterior tothe XIn and IJV and serves as an additional8