Patient Position: Supine, with head turned to contralateral side, as far as is comfortable for the patient. The ipsilateral arm should be adducted at the shoulder.

Indications: Shoulder or proximal arm surgery.

Volume of Local Anesthetic: 15 to 25 mL.

Needle Size: 22-gauge, 50-mm needle.

Ultrasonographic Landmarks: The sternocleidomastoid muscle lies superficial to the anterior and middle scalene muscles (Fig. 33-1). The nerve plexus is sandwiched between the scalene muscles. The carotid artery and internal jugular vein lie deep to the sternocleidomastoid muscle and medial to the brachial plexus at this level. In some patients, the vagus nerve may be seen between the carotid and jugular vein and the phrenic nerve may be seen lateral to the carotid artery and jugular vein as it courses over the anterior scalene muscle.

Transducer Position: Axial oblique plane, at approximately C6 level (Fig. 33-1). The transducer can be moved cephalad and caudad from this starting point to obtain the best image of the plexus elements.

Technique: The skin should be prepped in sterile fashion, and the transducer sterilized or covered with a sterile probe cover. Sterile sonographic gel is placed on the skin over the block site. The transducer is then placed on the skin at approximately the C6 level, and moved slowly cephalad or caudad to obtain an optimal image. The plexus can usually be found 1.5 to 2.5 cm lateral to the border of the internal jugular vein. Ideally, two or three nerve roots or trunks can be imaged in vertical alignment (Fig. 33-1).