Human Anatomy Part 1 - K. A. Dyubenko, A. K. Kolomiytsev, Yu. B. Chaykovsky 2002

Special Part
Joints of the bones of the upper limb, juncturae membri superioris — Joints of the forearm bones
Joints of the hand

The JOINTS OF THE hand, articulationes manus, include:

- radiocarpal joint, art. radiocarpalis

- midcarpal joint, art. mediocarpalis

- intercarpal joints, artt. intercarpales

- pisiform joint, art. ossis pisiformis

- carpometacarpal joints, artt. carpometacarpales

- intermetacarpal joints, artt. intermetacarpales

- metacarpophalangeal joints, artt. metacarpophalangeales

- interphalangeal joints, artt. interphalangeales

The radiocarpal joint, art. radiocarpalis, is a compound joint. Based on the shape of its articular surfaces, it is ellipsoid (see Fig. 92). The joint is formed by the articular surface of the radius and the proximal row of Carpal Bones (scaphoid, lunate, and triquetrum). The articular Cartilage completely separates the distal radioulnar joint from the radiocarpal joint. The articular capsule is relatively loose and attached along the margins of the articular surfaces.

Movements in this joint are combined with movements in the midcarpal joint. Movements are possible around the frontal axis (flexion and extension) and the sagittal axis (abduction and adduction).

The joint is reinforced by the following ligaments:

- radial collateral ligament of the carpus, lig. collaterale carpi radiale, extending from the styloid process of the radius to the scaphoid;

- ulnar collateral ligament of the carpus, lig. collaterale carpi ulnare, extending from the styloid process of the ulna to the triquetrum;

- palmar radiocarpal ligament, lig. radiocarpale palmare, originating from the styloid process of the radius and attaching to the BONES OF THE proximal carpal row;

- dorsal radiocarpal ligament, lig. radiocarpale dorsale, originating on the posterior surface of the distal end of the radius and attaching to the bones of the proximal carpal row;

- palmar ulnocarpal ligament, lig. ulnocarpale palmare.

The midcarpal joint, art. mediocarpalis, is an articulation formed between the proximal and distal rows of carpal bones (see Fig. 92). It shares a common articular capsule and Functions as a combined joint. The joint space is S-shaped. Movements in the midcarpal joint are closely linked with those in the radiocarpal joint and occur around the frontal and sagittal axes. The midcarpal joint has a separate articular capsule and is reinforced by the same ligaments as the radiocarpal joint.

The intercarpal joints, artt. intercarpales, connect the carpal bones to one another. These joints are reinforced by the following ligaments:

- interosseous intercarpal ligaments, ligg. intercarpea interossea;

- PALMAR AND DORSAL intercarpal ligaments, ligg. intercarpea palmaria et dorsalia (Fig. 93).

The pisiform joint, art. ossis pisiformis, is located within the tendon of the flexor carpi ulnaris and forms an articulation with the triquetrum, featuring an articular capsule secured by two ligaments: the pisohamate ligament, lig. pisohamatum, and the pisometacarpal ligament, lig. pisometacarpeum.

The carpometacarpal joints, artt. carpometacarpales, are formed by the Articulation of the second row of carpal bones with the bases of the II–V Metacarpal bones (see Fig. 92). They are firmly interconnected and mechanically act as a single unit—the rigid foundation of the hand (V. M. Tonkov). By the shape of their articular surfaces, the II–IV carpometacarpal joints are plane joints. They are secured by palmar and dorsal carpometacarpal ligaments, ligg. carpometacarpalia palmaria et dorsalia. Movements in these joints are minimal (5–10°), classifying them as amphiarthroses, or fixed joints (V. G. Kasyanenko, 1950–1956; S. F. Manziy, 1952).

The carpometacarpal joint of the thumb, art. carpometacarppea pollicis, is formed by the trapezium and the Base of the I metacarpal bone (see Fig. 92). Based on the shape of its articular surfaces, it is a saddle joint. Movements in this joint occur around two axes: the frontal axis (opposition and its reverse movement, reposition) and the sagittal axis (abduction, adduction, and circumduction). The thumb's ability of opposition distinguishes the human hand from that of animals, enabling it to grasp objects.

The intermetacarpal joints, artt. intermetacarpales, are situated between the bases of the II–V metacarpal bones. The contacting surfaces are bound by strong interosseous metacarpal ligaments, ligg. metacarpea interossea. The articular capsules are reinforced by palmar and dorsal metacarpal ligaments, ligg. metacarpea palmaria et dorsalia.

¹ Tonkov, Vladimir Mykolayovych (1872–1954) was a prominent Russian anatomist and lieutenant general of the medical service. From 1915, he headed the Department of Anatomy at the Military Medical Academy and authored the textbook Human Anatomy, which went through six editions between 1908 and 1962.

The metacarpophalangeal joints, art. metacarpophalangeae, are formed by the heads of the metacarpal bones and the articular facets at the bases of the proximal Phalanges of the fingers (Fig. 93A).

The metacarpophalangeal joints of digits II–V are spheroidal in shape, whereas the joint of the thumb, art. carpometacarpalis pollicis, is saddle-shaped. These joints are reinforced medially and laterally by collateral ligaments, ligg. collateralia, and on the palmar aspect by palmar ligaments, ligg. palmaria, as well as the deep transverse metacarpal ligament, lig. metacarpeum transversum profundum. Movements in the metacarpophalangeal joints of digits II–V occur around two axes: a frontal axis (flexion and extension) and a sagittal axis (abduction and adduction); passive rotational movements are also possible. In the first metacarpophalangeal articulation, only flexion and extension take place.

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Fig. 93. Radiocarpal joint, articulatio radiocarpea: A — ligaments and joints of the PALMAR ASPECT OF the hand

Fig. 93. Radiocarpal joint, articulatio radiocarpea (Continued): B — ligaments and joints of the dorsal aspect of the hand

The interphalangeal joints, art. interphalangeae (see Fig. 93), are located between the HEAD and base of the middle phalanx, as well as between the head of the middle phalanx and the base of the distal phalanx. The articular surfaces are ginglymus (hinge) in shape. Collateral ligaments, ligg. collateralia, run along the sides of the joints, while palmar ligaments, ligg. palmaria, are situated on the palmar side. Movements in these joints occur around a frontal axis (flexion and extension). Of great importance is the transverse ligament — the flexor retinaculum, retinaculum flexorum — spanning between the bony prominences of the radial and ulnar sides of the palmar aspect. This ligament is a thickening of the Fascia of the forearm. Bridging across, it converts the carpal sulcus into the carpal tunnel, canalis carpi, through which the tendons of the digital flexors and the median nerve pass.

Blood supply. The joints of the hand are supplied by the deep palmar arterial arch and the palmar and dorsal carpal arterial networks, rete carpi palmare et dorsale. Venous drainage is directed into the deep Veins OF THE hand and subsequently into the vv. ulnares, radiales, et interossea.

Lymphatic drainage is carried out via deep Lymphatic vessels into the cubital and axillary Lymph Nodes, nodi lymphatici cubitales et axillares.

Innervation. The joint capsules are innervated by Branches of the median nerve, n. medianus, radial nerve, n. radialis, and the deep branch of the ulnar nerve, n. ulnaris.