Ultrasound of the Hook of Hamate Region: Pictorial Review

Abstract

The hook of hamate is a complex anatomical region with many small but important structures. A sound knowledge of anatomy along with a systematic ultrasound technique can help delineate a variety of disorders. In this pictorial review, we discuss the ultrasound anatomy and the possible pathologies that can be encountered in this region.

Ultrasound of the Ulnar Nerve: A Pictorial Review

“…60 These cysts may also arise from the triquetro-hamate joint or, more rarely, the ulnocarpal or other carpal joints. 60,61 US can finely depict nerve enlargement near the avascular cyst, whereas MRI may be more accurate than US for demonstrating its articular origin. 58 In our experience, a ganglion cyst at the Guyon's canal can cause relevant nerve compression, particularly when the cysts are located near the hook of the hamate, due to the narrow space where the DBUN passes the pisohamate hiatus under the fibrous arcade of the hypothenar muscles (Figure 25).…”

“…58 In our experience, a ganglion cyst at the Guyon's canal can cause relevant nerve compression, particularly when the cysts are located near the hook of the hamate, due to the narrow space where the DBUN passes the pisohamate hiatus under the fibrous arcade of the hypothenar muscles (Figure 25). 61,62 Moreover, US can be a guide to aspiration and/or injections in these cases. 63 A pisiform-hamate coalition has been reported to possibly compress the DBUN.…”

“…69 The SBUN and the DBUN should therefore be carefully evaluated. 61 Repetitive microtrauma (Figure 27), as in sports like cycling, is reported to possibly determine UN palsy. 70,71 High-frequency US (with transducers at least up to 18 MHz) has been proven to be a valid tool with which to demonstrate the affected branch/es.…”

Ultrasound of the Ulnar Nerve: A Pictorial Review

“… 43 The DBUN along its course provides branches to the intrinsic muscle of the hand (see Figure 10); usually, the first is to the abductor digiti minimi and this small branch can be demonstrated in some patients with high‐frequency transducers (Figure 13). 43 To better follow the DBUN at the distal part of the Guyon's canal, it is useful to tilt the transducer over the ulnar part of the wrist, so that its relation with the HH can be demonstrated 52 . Distal to the Guyon's canal, the DBUN passes between the opponens digiti minimi muscle and the fourth palmar interosseous muscle, to redirect radially with the deep palmar arch, beneath the flexor tendons.…”

“…43 To better follow the DBUN at the distal part of the Guyon's canal, it is useful to tilt the transducer over the ulnar part of the wrist, so that its relation with the HH can be demonstrated. 52 Distal to the Guyon's canal, the DBUN passes between the opponens digiti minimi muscle and the fourth palmar interosseous muscle, to redirect radially with the deep palmar arch, beneath the flexor tendons. An axial-oblique sonogram is needed to follow the motor branch along its course (Figure 12D).…”