Snapping Triceps Syndrome

Dynamic US of the elbow can be used to help demonstrate abnormal dislocation of the ulnar nerve, with or without snapping triceps syndrome. This finding typically occurs in the cubital tunnel, an osteofibrous tunnel formed by a groove between the olecranon and the medial epicondyle and bridged by the Osborn retinaculum. As described in Chapter 8, dynamic scanning during full elbow flexion can allow continual depiction of the intermittent dislo-... 

Jacobson JA, Jebson PJL, Jeffers AW et al (2001) Ulnar nerve dislocation and snapping triceps syndrome diagnosis with dynamic sonography - report of three cases. Radiology 220 601-605... 

With elbowflexion, anterior dislocation of the medial head of triceps muscle relative to the medial epicondyle can occur in combination with dislocation of the ulnar nerve. In this condition, referred to as snapping triceps syndrome , the dislocation of the muscle leads to concurrent dislocation of the adjacent ulnar nerve as these structures are contiguous (Fig. 8.64). Two palpable snaps are typicaUy appreciated over the medial elbow, the first one reflecting dislocation of the ulnar nerve and the second, dislocation of the medial head of triceps muscle. The clinical presen-... 

Fig. 8.64a,b. Snapping triceps syndrome. Schematic drawings of the posterior aspect of the elbow in a extension and b 90° flexion demonstrate the ulnar nerve (arrows) as it passes through the cubital tunnel and a prominent medial head (mh) of the triceps muscle (tin). Note the absence of the Osborne retinaculum when compared with Fig. 8.7c. With elbow flexion, the medial edge of the triceps (arrowheads) and the ulnar nerve move anterior to the tip of the epicondyle. T, distal triceps tendon /c , flexor carpi ulnaris...

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