Wrist

Anatomy

Osteology

The bones constituting the wrist are represented by the lower end of the radius, the ulna (or ulna), of the first line (arranged proximale) and the second line of the bones of the carpus.

The lower end of the radius bulky, is slightly flattened d´avant behind. Its articular surface is called the radial glene . Its external face is prolonged by l´apophyse styloïde radial. Its lower face has two articular surfaces: an external surface for the scaphoïde and a surface intern for the semilunar . Its inner face has an articular surface for the head of the ulna. The lower end of the ulna (head of the ulna) presents two osseous projections. The head of the ulna, which with the shape d´un segment of sphere is covered by the triangular Ligament wrist. The former and external part s´articule with the radius, on the level of ulnar incisure. L´apophyse styloïde of the ulna is located as an postéro-intern.

The first line of the Os of the carpus is made up of the scaphoïde, of the semilunar (or lunatum), of the pyramidal (or triquetrum), and of the pea-shaped Os.

The second line (arranged distal) is made up of the trapezoid (or trapezium), of the trapezoidal (or trapezoidum), of the large-bone (or capitatum) and of the hooked bone (or hamatum).

Arthrology

The radiocarpal articulation

The radiocarpal articulation links on the one hand the Cavité glénoïde of the lower end of the radius, the head of the ulna and, on the other hand, the condyle carpien composed of articular surfaces of the scaphoïde, the semilunar , and the pyramidal .

It is consisted of the radial Cavité glénoïde , of the head of the ulna. These two elements articulate on this level by the means of the complex fibro cartilagineux triangular, also called triangular Ligament) and the first line of the Os of the carpus.

Articular surfaces higher of the scaphoïde and the semilunar respectively articulate with the radial Cavité glénoïde by the means of the articular small cavity scaphoïdienne and the articular small cavity lunarienne.

The Cavité glénoïde is prolonged towards the inside by the lower face of the complex fibro cartilagineux triangular, which the higher articular surface of the pyramidal answers. It is about an articulation of the type condylienne having two degrees of articular mobility.

The articular capsule is loose and thin behind and is reinforced by many Ligament S.

Articulation médio-carpienne

It joins together as for it the two lines of the carpus. Its articular line space is in form of " S".

The first curve, convex to the bottom, represents the articular line space between the scaphoïde and the block trapezoid - trapezoidal.

The second curve, concave downwards, represents as for it the articular line space between the large-bone and the hooked bone on the one hand and the scaphoïde, the semilunar and the pyramidal on the other hand.

The Os constituting the line proximale have a certain mobility the ones compared to the others, contrary to the distal line whose bones are plain between them and to the métacarpiens by rather rigid Ligament S.

The articular capsule is enough " serrée" ahead, but coward behind.

Articulations carpo-métacarpiennes

It is about different the articulation S between the five métacarpiens and the second line from the bones from the carpus.

The system ligamentaire

The system Ligament surface of the wrist must be a right balance between the constraints necessary to the maintenance of the stability of the wrist and the great handiness which characterizes this area.

No Muscle fitting on the line proximale of the Os of the carpus, the stability of this one depends exclusively on the Ligament S which stick to it or which cross it.

The palmar ligamentaire plan (former) is thick and resistant whereas the dorsal plan (posterior) is finer and less important. The majority of the ligaments of the wrist is palmar and intra-capsulaire. The function of different the Ligament S is explained by the orientation of their fibers.

The ligaments of the wrist were the subject of many studies. Descriptions and Nomenclature S, just as classifications, are numerous; this because of a great variability enters the individuals.

Palmar system ligamentaire (former)

It includes/understands Ligament S known as extrinsic which link both Os of the Avant-bras to the bones of the carpus and the ligaments known as intrinsic , which links the bones of the carpus the ones with the others.

The general configuration of the palmar ligaments is a structure in " V" with a zone of potential weakness (the space of Pear tree) located above the articulation luno-capital (articulation enters the semilunar and the large bone).

The palmar ligamentaire plan is made up various often intricate formations the ones with the others and difficult to differentiate.

Extrinsic ligaments

They gather the radiocarpal ligaments (between the radius and the bones of the carpus) and the ligaments ulno-carpiens (between the ulna and the bones of the carpus).

The radiocarpal ligaments have a whole a insertion proximale on the level of the lower end of the radius and a distal insertion on one or more bone of the carpus:

the ligament radio-scapho-capital takes its origin on the level of the former edge of articular surface radial. It is directed to the bottom and the inside, and will fit into the level of the scaphoïde. Fibers will intersect with those of the ligament ulno-capital. A small portion of this ligament will fit as for her on the large bone.
the radio-lunar ligament fits in inside of the ligament radio-scapho-capital. Its starting point is located on the former edge of articular surface radial, its fibers are parallel to those of the ligament radio-scapho-capital. It passes above the scaphoïde without sticking to it. It is divided into two beams: the long portion and the short portion.
the radio-scapho-lunar ligament (or ligament of Testut), whose origin is between the long and short portion radio-lunar ligament, sees its fibers being lost in the scapho-lunar interosseux ligament. It corresponds to the former brake of the semilunar .

The ligaments ulno-carpiens include/understand:

the ligament ulno-capital takes its origin directly on the level of the head of the ulna, on the level of the fovea. It is oblique to the bottom and the outside. During its way, it will reinforce the palmar portion of the interosseux ligament luno-triquetral; then, on the level of the articulation médio-carpienne, it will be directed radially and its fibers go intriquer to those of the ligament radio-scapho-capital. It also will leave some fibers for the large bone.
the ulno-lunar ligament takes as for him its origin of the palmar radio-ulnar ligament. It is located beside the radio-lunar ligament court of which it follows the direction, then fits on the palmar face of the semilunar .
the ligament ulno-triquetral also takes its origin of the palmar radio-ulnar ligament, apart from the precedent, and will fit on the pyramidal .

Intrinsic ligaments

They gather the Ligament S scapho-trapézo-trapézoidien, scapho-capital, triquetro-capital and triquetro-hamatien.

the ligament scapho-trapézo-trapézoidien fits on the distal pole of the Scaphoïde, then is divided into two in the form of a " V" reversed whose branches will fit respectively on the trapezoid and the trapezoidal .
the ligament scapho-capital also has its origin on the distal pole of the scaphoïde, is oblique to the bottom and the inside, and will fit on the external edge of the body of the large bone.
the ligament triquetro-capital takes its proximale insertion on the level of the pyramidal , is oblique to the bottom and the outside, and fits on the external edge of the body of the large bone.
the ligament triquetro-hamatien fits on the pyramidal , into external compared to the precedent, and will join the palmar face (former) of the hooked bone.

Dorsal system ligamentaire (posterior)

Extrinsic ligaments

The dorsal Ligament radiocarpal is tightened posterior edge of lower articular surface radial. It is oblique to the bottom and of inside, and will fit on the posterior tuber of the pyramidal by giving up fibers for the semilunar and on the dorsal portion of the interosseux ligament luno-triquetral. It was also referred by certain authors under the term of dorsal radio-triquetral ligament and dorsal radio-luno-triquetral ligament, whose lunar beam corresponds to the posterior brake of the semilunar .

Intrinsic ligaments

The ligament inter-carpien dorsal takes its origin of the scaphoïde, sticks on the posterior horn of the semilunar to go to finish with the posterior face of the pyramidal . It is sometimes described giving fibers towards the large bone, the trapezoid or the trapezoidal . For other authors, these last fibers constitute another ligament with whole share.

There exists an inconstant reinforcement capsulaire, which is then called ligament triquetro-hamatien dorsal, tightened between the pyramidal and the hooked bone.

Interosseux ligaments

Proximaux ligaments

They are two. They cover the face proximale, palmar and dorsal of their respective articulation S. Each part has histological characteristics different which make it possible to divide them into palmar, dorsal area and proximale.

the scapho-lunar interosseux ligament is tended between the scaphoïde and the semilunar . Its palmar beam is fine and its fibers are directed obliquely. Its dorsal beam consists of solid fibers of Collagène transversely directed. Its beam proximal is fibro cartilagineux.
the interosseux ligament luno-triquetral is tended between the semilunar and the pyramidal . Its palmar beam is made of transverse fibers. Its dorsal beam is finer; its fibers pass in bridge above the ligament luno-triquetral. Its beam proximal is fibro-cartilagineux. It is more powerful and less flexible than the scapho-lunar ligament and authorizes only few movements between the bones which it joins together.

Distal ligaments

They are represented by:

the Ligament interosseux trapézo-trapézoidien linking the trapezoid with the trapezoidal ,
the interosseux ligament trapézoïdo-capital linking of the trapezoidal to the large bone,
the ligament triquetro-capital, linking the pyramidal with the large bone,
the interosseux ligament capito-hamatien linking the large bone with the hooked bone.

Each one of them is divided into a palmar component and a dorsal component, the two last having moreover one deep component.

The whole of the Ligament S previously described linking the large bone with the other bones of the carpus form a spangled structure called radiated ligament of Pear tree .

It should be noted that there does not exist direct connection between the semilunar and the bones of the distal line and in particular of ligament luno-capital, this decreasing the stability of semilunar on the head of the large bone.

Biomechanics of the wrist

From the home position, the wrist has two degrees of mobility:

movements of laterality: the Abduction (or radial slope ) and the Adduction (or cubital slope ),
the Inflection (or palmar inflection) and the Extension (or dorsal inflection).

The combination, to various degrees, from these movements will allow the wrist a broad sector of mobility.

Movements of laterality

At the time of the movements of laterality, the Os of the first line of the carpus describe a harmonious and synchronous movement of rotation around a dorso-palmar axis passing by the head of the large bone.

These movements take place on the level of the articulation S radiocarpal and médio-carpienne according to a variable distribution.

Abduction

Still called radial deviation, this movement has an amplitude from approximately 15 with 25°, two thirds of the movement taking place on the level of the articulation médio-carpienne.

The scaphoïde rocks according to its main roads and horizontalise, its pole proximal moving backwards, involving a reduction in " space utile" between the block trapézo - trapézoïdien and the radial glene , which allows the trapezoid and the trapezoidal to approach the radius. The trapezoidal and the second Métacarpien being firmly linked, this causes a traction on this functional unit. The semilunar slightly will rock its posterior horn forwards (palmar inflection). The pyramidal , as for him, slips along its common articular surface with the hooked bone, putting him also in palmar inflection.

All these individual movements will result in a setting into Flection of the first line of the bones of the carpus.

At the time of this movement, the mechanical constraints on the level of the scapho-lunar interosseux ligament are important.

Adduction

Still called cubital deviation, this movement has an amplitude from approximately 40 with 50°, half of this movement taking place on the level of the articulation médio-carpienne.

The scaphoïde goes verticaliser, accompanied by a light palmar rocker of its pole proximal, involving a radial slip of the first line of the bones of the carpus: the semilunar is thus seen imposing a dorsal rocker (extension), while rocking towards the inside, which moves away it from the Scaphoïde. The large bone will rock in inside on the level of its distal end and will tend to drive out the Scaphoïde radial side, which increases the difference between the Scaphoïde and the semilunar . The pyramidal also goes, at the time of this movement, to slip along its articular interface with the hooked bone, movement which will be translated this time by a dorsal inflection.

The association of these individual movements will result in a setting into Extension of the first line of the bones of the carpus.

Movements of inflection - extension

The movements of Inflection and Extension take place on the level of the articulation S radiocarpal and médio-carpienne according to a variable distribution.

The bones of the first line of the carpus move forwards during the extension and the back at the time of the inflection, in a joint way even if the amplitude of movement of the scaphoïde is more important than that of the semilunar or of the pyramidal (this because of the structure of the scapho-lunar Ligament interosseux which is looser in its former part than posterior).

The amplitude of the movements of inflection and extension is of approximately 85°. The movement of inflection takes place for 40% in the radiocarpal articulation and 60% in the articulation médio-carpienne. The movement of extension takes place for 70% in the radiocarpal articulation and 30% in the articulation médio-carpienne.

In inflection, the scaphoïde rocks behind on the level of its pole proximal, and thus tends to horizontaliser. The semilunar , as for him, rocks in inflection. In extension, the scaphoïde goes verticaliser and the semilunar one will rock in extension. The scapho-lunar angle thus opens in extension and is closed in inflection.

At the time of the movement of inflection, the inflection of the Scaphoïde is accompanied by a pronation and that by the semilunar of a supination. What tends to bring closer the two bones. In extension, the Scaphoïde describes on the contrary a movement of supination and the semilunar , a movement of pronation, which thus tends to move away these two bones.

The axes of movements are transverse and pass by the semilunar for the first line and by the large bone for the second line.

Associations of movements

The movements of inflection, of extension as well as the movements of laterality are not simple movements which are carried out around one only axis but are generally associated.

Thus, at the time of the Abduction, a dorsal inflection occurs in the first line of the bones of the carpus, but this movement is not apparent because it is compensated by a palmar inflection of the second line. Moreover, the first line is put in Supination, while the second line is put in Pronation, movements which are also cancelled.

The Adduction, as for it, is accompanied by an inflection and Pronation of the first line and by an extension and Supination of the second line. These movements are cancelled thus.

The Flection is automatically associated with a radial slope while the Extension is associated with a cubital slope.

Certain limitations of amplitude are related to the structure of the massive carpien. Thus a movement of abduction is not possible in the maximum palmar inflection, because the first line of the bones of the carpus cannot then move, nor to rock.

Pathologies of the wrist

Fractures

fracture of the scaphoïde: it constitutes 70% of the Fracture S interesting the bones of the carpus,
fracture of Pouteau-Adhesives: most frequent, it corresponds to a fracture of the lower end of the radius and ulnar head with dorsal and radial displacement, secondary with a fall on the hand with elbow tended, the Avant-bras in Pronation and wrist in Extension and radial deviation,
fracture of Goyrand-Smith: fracture lower end of the radius with palmar, secondary displacement with a fall on the hand with elbow tended, before arm in Supination and wrist in Flection and ulnar deviation,
perish-lunar Luxation of the carpus: under this term is gathered a large range of lesion S which in common has the loss of contact between the large bone and the semilunar , and a disorganization of the line proximale of the carpus.

Others

distorsion S,
Tendinitis S,
Pseudarthrose,
Osteoarthritis,
Algodystrophie,
rupture of the Tendon of the long bungee cord of the inch 2-3 month post fracture of Pouteau-Adhesives.

See

Articulation (anatomy)
Radius
Ulna
Carp

External bond

Imagery of the wrist - Ostéo-Articular Center of Imagery - Private clinic of the sport of Bordeaux Mérignac

References

Bonnel F., Allieu Y. radio-cubito-carpienne articulations and médio-carpienne. Anatomical organization and biomechanical bases. Ann Chir Hand 1984 ; 3 (4): 287-296.
Kapandji A. Biomécanique of the carpus and the wrist. Ann Chir Hand 1987 ; 6 (2): 147-169.
Oberlin C. instabilities and désaxations of the carpus. Anatomical bases, clinical study and radiological. Conferences of Teaching of the SOFCOT 1990 ; 38: 235-250.
Shepherd R.A. The anatomy and BASIC biomechanics off the wrist joint. J Hand Ther 1996 ; 9: 84 93.
Shepherd R.A. distal The anatomy off the joined ligaments off the wrist and radioulnar. Orthop Covering joint 2001 ; 383: 32-40.
Viegas S.F. Dorsal The ligaments off the wrist. Hand Covering joint 2001 ; 17 (1): 65-75.

Fiu-vro: Käejakk Simple: Wrist

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