A linear transducer is placed in a transverse position over the interscalene area (Fig. 43-1). The brachial plexus is visualized in cross section and a series of anechoic circles is seen between the anterior and middle scalene muscle and beneath the sternocleidomastoid muscle (Fig. 43-1). The block needle is inserted posterior to the probe using an in plane technique (Fig. 43-1). This technique is especially useful when the practitioner wishes to target the lower roots of the brachial plexus. This approach allows for direct visualization of
the needle in real time. When inserting a catheter for postoperative analgesia after shoulder surgery, the upper roots of the brachial plexus need to be blocked. In this setting, it may be preferable to insert the needle inferior to the probe using an out of plane technique (Fig. 43-2). The needle is directed cephalad to the plexus and the catheter is placed adjacent to roots C5 and C6. Diffusion of the local anesthetic around the roots is seen after injection (Fig. 43-3).

The landmark point for the infraclavicular nerve block is the coracoid process. With the arm abducted, to better expose the axillary vessels, the probe is placed 1 to 1.5 cm below
the coracoid process in the saggital plane. The needle is introduced superior to the probe and introduced nearly perpendicular to the skin (Fig. 43-4). The needle is advanced through the pectoralis major and minor muscles toward the lateral cord. Local anesthetic is injected around the lateral cord (Fig. 43-5). The needle is then redirected underneath the axillary artery to reach the posterior cord (Fig. 43-6). The same technique can be used to selectively block the medial cord. In older children it is useful to block each cord. In younger children it is sufficient to inject the local anesthetic around one cord and allow it to diffuse to the other cords.