Figure 1 schematizes the anatomy of the interosseous ligaments. The functions of this group are maintaining transverse cohesion, and thus stability, as well as limiting and/or guiding of the segmental movements. The stiffness of the interosseous ligaments is lower than that of the extrinsic ligaments, because of a more important type III collagen content, which allows interosseous ligaments to lengthen more compared to extrinsic ligaments. Their failure load is regarded as higher than that of the extrinsic ligaments [3–5, 11, 18, 24, 27, 30, 34, 35, 38, 43, 44, 49, 55, 56, 58, 63, 69, 71, 73, 77, 78, 81–83, 87, 92, 95].

The distal interosseous ligaments are shorter and more resistant than the proximal ones, offering thus less freedom of movement to the bones of the distal carpus. The distal ligaments present a dorsal part, connecting the dorsal faces of the ­adjacent bones and a deep portion, located palmarly and connecting the interosseous faces of the adjacent bones. Their incomplete character allows communication between the midcarpal space and the carpometacarpal joint spaces.

The interosseous ligaments of the proximal carpus (Fig. 1b, c) have been studied extensively. They are described as a crown or a cap, surrounding the proximal, dorsal, and palmar edges of the corresponding articular surfaces. The proximal part of the two ligaments consists of fibrocartilage, with collagen fibers without preferential orientation. This part carries the radiocarpal cartilage but does not contribute to stabilization or limitation of movements. The dorsal part of the scapholunate ligament and the palmar part of the lunotriquetral ligament are short and resistant, limiting translations (∼70 % of resistance to translation) and serve as point pivot to the segmental movements. On the opposite, the palmar part of the scapholunate ligament and the dorsal part of the lunotriquetral ligament are longer and less resistant, present oblique fibers, and limit segmental rotations (∼60 % of resistance to rotation). This provision implies a cam effect during movements, with a dorsal pivot in the scapholunate space and a palmar pivot on the lunotriquetral side. It also implies a suspension of the lunate in torsion between the scaphoid and the triquetrum.

Sennwald and Segmüller [78] present the palmar ligaments as two “V”-shaped structures, the proximal palmar “V” and the distal palmar “V” (Fig. 2a). These structures include part of the radiocarpal (except the short radiolunate ligament) and ulnocarpal (except the ulnocapitate and ulnotriquetral ligaments) ligaments from the classical descriptions (Fig. 2c). The dimensions of the main palmar ligaments are presented in Table 2 [2, 3, 6, 8, 11, 14, 16, 21, 25, 39, 51, 55, 57, 60, 61, 63, 69, 71, 73, 75, 78, 84, 93, 94, 96].

Besides their attachment at the palmar surface of the capitate, the ulnocapitate and radiocapitate ligaments merge through interwoven fibers in front of the lunocapitate joint line (Fig. 2c).

The radioscapholunate ligament is a loose and little organized connective tissue, constituting the vascular sheath of the proximal arteries for the scaphoid and lunate. Its mechanical resistance is low compared to the other palmar ligaments (failure load of 40 N and elongation to failure of 174 % versus 150 N and 125 % for the radiocapitate ligament, for instance).

The main roles of the palmar ligaments are the limitation of radial (ulnocarpal ligaments) and ulnar deviation (radiocarpal ligaments), as well as of dorsal flexion. They also prevent ulnar, anterior, and posterior translations. They have an important role in carpal stability and are supposed to contribute to the determination of movements. Moreover, the radiocarpal ligaments limit intracarpal pronation and maintain the scaphoid.

Berger and Amadio [6] and Siegel and Gelberman [84] showed that the knowledge of ligamentous insertions on the distal radius (Fig. 2d) could contribute to the evaluation of functional implications of distal radius fractures or styloidectomy.

Also, most studies describe the radiocarpal ligaments as displaying a relatively constant morphology, in contrast with the ulnocarpal ligaments. The latter vary significantly, concerning their general morphology as well as their dimensions. However, the presence of two radiolunate ligaments (long and short), described in many studies, was not observed in 40 % of the cases in our work [22].

The palmar scaphotriquetral ligament was not described by most authors. Sennwald et al. [79] showed its situation deep to the palmar ligaments, crossing the palmar surface of the head of the capitate and connecting the waist of the scaphoid to the palmar surface of the triquetrum.

The support of the distal pole of the scaphoid is ensured by the scaphotrapezial, scaphocapitate, and capitotrapezial ligaments (Fig. 2b).

At the dorsal aspect of the carpus, the dorsal radiocarpal or dorsal radiotriquetral ligament and the dorsal intercarpal or dorsal scaphotriquetral ligament form a “V”-shaped structure with its apex at the level of the ligamentous crest of the triquetrum (Fig. 3). This structure constitutes the dorsal “V” of Sennwald and Segmüller [78].

The morphological variability of the dorsal ligaments is much larger than that of the palmar ligaments, as shown by many studies [11, 14, 16, 21, 22, 33, 49, 53, 55, 59, 69, 71, 73, 77, 78, 91, 94, 96]. The dimensions of the dorsal ligaments are presented in Table 2.

The dorsal radiotriquetral ligament limits intracarpal supination, radial deviation, palmar flexion, and ulnar translation of the carpus. As a whole, the “V” dorsal limits palmar flexion. These ligaments contribute also significantly to carpal ­stability by the support offered to the lunate and their role in longitudinal and transverse wrist cohesion. The dorsal radiocarpal ligament is a relatively strong structure, displaying a failure load of approximately 150 NR and a tangential modulus of 30 MPa, in spite of a low thickness (1 mm). The dorsal intercarpal ligament is characterized by a failure load of approximately 80 NR and a tangential modulus of 45 MPa.

Finally, the dorsal ligaments are very rich in nervous endings compared to the palmar ligaments. Approximately 80 % of these terminations are observed near ligament insertions and 80 % in the epi-ligamentous sheath.

Regarded as the pulley of the extensor carpi ulnaris, the triangular fibrocartilage complex (Fig. 4) consists of several poorly dissociated elements. The triangular fibrocartilage itself is supplemented by several associated structures, the palmar and dorsal radioulnar ligaments, the palmar ulnolunate ligament, the ulnotriquetral ligament, the ulnocapitate ligament, the ulnocarpal meniscus, the prestyloid recess, the ulnar collateral ligament, and the sheath of the extensor carpi ulnaris. The dimensions of the components of this complex are presented in Tables 2 and 3 [1, 15, 16, 64, 66–68, 75, 76, 78, 90].