Fish

The wrist joint is formed by the distal radioulnar and radiocarpal joints.

The distal radioulnar joint is a trochoid joint formed between the head of the ulna and the ulnar notch at the lower end of the radius. It is joined by the joint capsule and joint disc.

Articular Capsule – It consists of bundles of fibers inserted in the margins of the ulnar notch and in the head of the ulna. It has two thickenings called Ventral Radioulnar Ligament and Dorsal Radioulnar Ligament .

Articular Disc – Triangular in shape and placed transversely under the head of the ulna, firmly joining the lower ends of the ulna and radius.

The radiocarpal joint (syndemosis) is a condylar joint. It is formed by the distal end of the radius and the distal surface of the articular disc with the scaphoid, lunate and pyramidal bones. The radiocarpal joint is formed by the following ligaments:

Palmar Radiocarpal Ligament – It is a wide membranous bundle inserted in the anterior margin of the distal end of the radius, in its styloid process and in the palmar aspect of the distal end of the ulna. Its fibers run distally to insert into the scaphoid, lunate, and pyramidal bones.

Dorsal Radiocarpal Ligament – It is less thick and resistant than the palmar one. Its proximal insertion is on the posterior edge of the distal end of the radius. Its fibers are directed obliquely in the distal and ulnar direction and are attached to the scaphoid, lunate and pyramidal bones.

Ulnar Collateral Ligament – It is a rounded cord inserted proximally to the tip of the styloid process of the ulna and distally to the pyramidal and pisiform bones.

Radial Collateral Ligament – Extends from the apex of the styloid process of the radius to the radial side of the scaphoid.

Distally to the joints studied above, we also find the intercarpal, carpometacarpal, intermetacarpal, metacarpophalangeal and interphalangeal joints.

BACK VIEW OF THE ARTICULAR STRUCTURES OF THE WRIST

Source: NETTER, Frank H.. Atlas of Human Anatomy. 2nd edition Porto Alegre: Artmed, 2000.

PALM VIEW OF THE ARTICULAR STRUCTURES OF THE HAND

Source: NETTER, Frank H.. Atlas of Human Anatomy. 2nd edition Porto Alegre: Artmed, 2000.