Midcarpal joint

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Midcarpal joint
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Vertical section through the articulations at the wrist, showing the synovial cavities.
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Ligaments of wrist. Anterior view
Details
Identifiers
Latin articulatio mediocarpalis
TA98 A03.5.11.102
TA2 1804
FMA 35293
Anatomical terminology

The midcarpal joint is formed by the scaphoid, lunate, and triquetral bones in the proximal row, and the trapezium, trapezoid, capitate, and hamate bones in the distal row. [1] The distal pole of the scaphoid articulates with two trapezial bones as a gliding type of joint. The proximal end of the scaphoid combines with the lunate and triquetrum to form a deep concavity that articulates with the convexity of the combined capitate and hamate in a form of diarthrodial, almost condyloid joint.

Contents

Description

The cavity of the midcarpal joint is very extensive and irregular. The major portion of the cavity is located between the distal surfaces of the scaphoid, lunate, and triquetrum and proximal surfaces of the four bones of the distal row. Proximal prolongations of the cavity occur between the scaphoid and lunate and between the lunate and triquetrum. These extensions reach almost to the proximal surface of the bones in the proximal row and are separated from the cavity of the radiocarpal joint by the thin interosseous ligaments. There are three distal prolongations of the midcarpal joint cavity between the four bones of the distal row. The joint space between trapezium and trapezoid, or that between trapezoid and capitate, may communicate with cavities of the carpometacarpal joints, most commonly the second and third. The cavity between the first metacarpal and carpus is always separate from the midcarpal joint; the joint cavity between the hamate and fourth and fifth metacarpals is a separate cavity more often than not, but it may communicate normally with the midcarpal joint.

The Wrist

The wrist is perhaps the most complicated joint in the body. It permits movements in two planes - extension/flexion, ulnar deviation/radial deviation - and allows complex patterns of motion under significant strain.

Optimal wrist function requires stability of the carpal components in all joint positions under static and dynamic conditions.

Stability is achieved by a sophisticated geometry of articular surfaces and intricate system of ligaments, retinacula, and tendons, which also determine the relative motion of the carpal bones.

Ligaments

Ligamentous Apparatus of the Wrist

The carpal bones are not interlocked solely by their shapes; rather, they are held together by interosseous ligaments and by volar, dorsal, radial, and ulnar ligaments. The ligaments holding the carpal bones to each other, to the distal radius and ulna, and to the proximal ends of the metacarpals can be described as extrinsic, or capsular, and intrinsic, or interosseous (intercarpal). The function of the ligamentous system is guiding and constraining certain patterns of motion. Some portion of the ligaments are under tension in every position of the hand in relation to the forearm.

Related Research Articles

Carpal bones Eight small bones that make up the wrist (or carpus) that connects the hand to the forearm

The carpal bones are the eight small bones that make up the wrist that connects the hand to the forearm. The term "carpus" is derived from the Latin carpus and the Greek καρπός (karpós), meaning "wrist". In human anatomy, the main role of the wrist is to facilitate effective positioning of the hand and powerful use of the extensors and flexors of the forearm, and the mobility of individual carpal bones increase the freedom of movements at the wrist.

Wrist Part of the arm between the lower arm and the hand

In human anatomy, the wrist is variously defined as 1) the carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand; (2) the wrist joint or radiocarpal joint, the joint between the radius and the carpus and; (3) the anatomical region surrounding the carpus including the distal parts of the bones of the forearm and the proximal parts of the metacarpus or five metacarpal bones and the series of joints between these bones, thus referred to as wrist joints. This region also includes the carpal tunnel, the anatomical snuff box, bracelet lines, the flexor retinaculum, and the extensor retinaculum.

Anatomical snuffbox

The anatomical snuff box or snuffbox is a triangular deepening on the radial, dorsal aspect of the hand—at the level of the carpal bones, specifically, the scaphoid and trapezium bones forming the floor. The name originates from the use of this surface for placing and then sniffing powdered tobacco, or "snuff." It is sometimes referred to by its French name tabatière.

Trapezoid bone

The trapezoid bone is a carpal bone in tetrapods, including humans. It is the smallest bone in the distal row of carpal bones that give structure to the palm of the hand. It may be known by its wedge-shaped form, the broad end of the wedge constituting the dorsal, the narrow end the palmar surface; and by its having four articular facets touching each other, and separated by sharp edges. It is homologous with the "second distal carpal" of reptiles and amphibians.

Trapezium (bone) Bone of the wrist

The trapezium bone is a carpal bone in the hand. It forms the radial border of the carpal tunnel.

Metacarpal bones

In human anatomy, the metacarpal bones or metacarpus, form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist which forms the connection to the forearm. The metacarpal bones are analogous to the metatarsal bones in the foot.

Scaphoid bone

The scaphoid bone is one of the carpal bones of the wrist. It is situated between the hand and forearm on the thumb side of the wrist. It forms the radial border of the carpal tunnel. The scaphoid bone is the largest bone of the proximal row of wrist bones, its long axis being from above downward, lateralward, and forward. It is approximately the size and shape of a medium cashew.

Capitate bone

The capitate bone is found in the center of the carpal bone region, colloquially known as the wrist, which is at the distal end of the radius and ulna bones. It articulates with the third metacarpal bone and forms the third carpometacarpal joint. The capitate bone is the largest of the carpal bones in the human hand. It presents, above, a rounded portion or head, which is received into the concavity formed by the scaphoid and lunate bones; a constricted portion or neck; and below this, the body. The bone is also found in many other mammals, and is homologous with the "third distal carpal" of reptiles and amphibians.

Hamate bone

The hamate bone or unciform bone is a bone in the human wrist readily distinguishable by its wedge shape and a hook-like process ("hamulus") projecting from its palmar surface.

Lunate bone

The lunate bone is a carpal bone in the human hand. It is distinguished by its deep concavity and crescentic outline. It is situated in the center of the proximal row carpal bones, which lie between the ulna and radius and the hand. The lunate carpal bone is situated between the lateral scaphoid bone and medial triquetral bone.

Radius (bone) One of the two long bones of the forearm

The radius or radial bone is one of the two large bones of the forearm, the other being the ulna. It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna. The ulna is usually slightly longer than the radius, but the radius is thicker. Therefore the radius is considered to be the larger of the two. It is a long bone, prism-shaped and slightly curved longitudinally.

Triquetral bone

The triquetral bone is located in the wrist on the medial side of the proximal row of the carpus between the lunate and pisiform bones. It is on the ulnar side of the hand, but does not articulate with the ulna. It connects with the pisiform, hamate, and lunate bones. It is the 3rd most commonly fractured carpal bone.

Kienböcks disease

Kienböck's disease is a disorder of the wrist. It is named for Dr. Robert Kienböck, a radiologist in Vienna, Austria who described osteomalacia of the lunate in 1910.

Carpometacarpal joint

The carpometacarpal (CMC) joints are five joints in the wrist that articulate the distal row of carpal bones and the proximal bases of the five metacarpal bones.

Palmar radiocarpal ligament

The palmar radiocarpal ligament is a broad membranous band, attached above to the distal end of the radius, to the scaphoid, lunate and the triquetrum of the carpal bones in the wrist. Some being continued to the capitate.

Intercarpal joints

The intercarpal joints can be subdivided into three sets of joints : Those of the proximal row of carpal bones, those of the distal row of carpal bones, and those of the two rows with each other.

Carpal tunnel

In the human body, the carpal tunnel or carpal canal is the passageway on the palmar side of the wrist that connects the forearm to the hand.

Hand Extremity at the end of an arm or forelimb

A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala are often described as having "hands" instead of paws on their front limbs. The raccoon is usually described as having "hands" though opposable thumbs are lacking.

Wrist osteoarthritis

Wrist osteoarthritis is a group of mechanical abnormalities resulting in joint destruction, which can occur in the wrist. These abnormalities include degeneration of cartilage and hypertrophic bone changes, which can lead to pain, swelling and loss of function. Osteoarthritis of the wrist is one of the most common conditions seen by hand surgeons.

References

This article incorporates text in the public domain from page 328 of the 20th edition of Gray's Anatomy (1918)

  1. Kaufmann, Robert A.; Pfaeffle, H. James; Blankenhorn, Brad D.; Stabile, Kathryne; Robertson, Doug; Goitz, Robert (September 2006). "Kinematics of the Midcarpal and Radiocarpal Joint in Flexion and Extension: An In Vitro Study". The Journal of Hand Surgery. 31 (7): 1142–1148. doi:10.1016/j.jhsa.2006.05.002. ISSN   0363-5023. PMID   16945717.