Question

Highlight the movements at the; Radio Carpal Joint, Intercarpal joints, Carpometacarpal joint and Mid carpal joints. High light the muscles involved in bringing about the movements listed above. Make reference to their proximal and distal attachment sites (origins and insertion sites)

Answer 1

The radiocarpal joint is where the radius bone of the forearm meets the first row of carpal bones in the lower hand.
The radiocarpal joint itself cannot rotate. It can only move side to side and up and down.
Its other movements include:

Flexion -This is the movement created when the wrist is bent so that the palm of the hand is angled closer to the inside of the wrist.
Extension -The opposite of flexion, this movement raises the back of the hand so that it’s closer to the top of the wrist and forearm.
Radial deviation -This movement involves tilting the wrist toward the thumb.
Ulnar deviation -This movement occurs when the wrist is tilted toward the little finger.

The primary movements of the radiocarpal joint are flexion, extension, abduction and adduction.
All the movements of the wrist are performed by the muscles of the forearm.

Flexion is mainly produced by the flexor carpi ulnaris and flexor carpi radialis, with the support from the flexor digitorum superficialis.
Extension is mainly produced by the extensor carpi radialis longus, extensor carpi radialis brevis, and extensor carpi ulnaris muscles, with assistance from extensor digitorum.
Adduction is produced by the extensor carpi ulnaris and flexor carpi ulnaris.
Abduction is produced by the abductor pollicis longus, flexor carpi radialis, extensor carpi radialis longus and extensor carpi radialis brevis.

The carpal bones are in two rows, a proximal and a distal. The bones in each row are attached closely to one another. The four bones of the proximal row are the scaphoid, the lunate, the triquetral, and the pisiform, which sits by itself on the triquetral. The scaphoid, the lunate and part of the triquetral articulate with the distal end of the radius, to form the radio-carpal joint.

The distal surface of the proximal row forms a deeply concave notch, which the bones of the distal row fit into. The bones of the distal row are the trapezium, the trapezoid, the capitate, and the hamate. The capitate and part of the hamate project proximally.

The bases of the five metacarpals articulate with the distal row of carpal bones. The first, the one for the thumb, articulates by itself with the trapezium. The other four articulate in a row, here. The distal row of carpal bones articulates with the proximal row here, to form the midcarpal joint. The projecting capitate and hamate fit into the notch in the proximal row.

When flexion and extension occur at the wrist, the movement happens partly at the radiocarpal joint ,and partly at the midcarpal joint. When radial deviation and ulnar deviation occur, the action happens mainly at the radio-carpal joint.

The intercarpal joints (joints of the carpal bones of the wrist) can be subdivided into three sets of joints (also called articulations): 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.
The bones in each carpal row interlock with each other and each row can therefore be considered a single joint. In the proximal row a limited degree of mobility is possible, but the bones of the distal row are connected to each other and to the metacarpal bones by strong ligaments that make this row and the metacarpus a functional entity.

The articulation of the hand and wrist considered as a whole involves four articular surfaces:

(a) the inferior surfaces of the radius and articular disk
(b) the superior surfaces of the scaphoid, lunate, and triangular, the pisiform having no essential part in the movement of the hand
(c) the S-shaped surface formed by the inferior surfaces of the scaphoid, lunate, and triangular
(d) the reciprocal surface formed by the upper surfaces of the bones of the second row.

These four surfaces form two joints:

(1) a proximal, the wrist-joint proper; and

(2) a distal, the mid-carpal 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.
The CMC joint of the thumb or the first CMC joint, also known as the trapeziometacarpal (TMC) joint, differs from the other four CMC joints.
The carpometacarpal joint of the thumb (pollex), also known as the first carpometacarpal joint, or the trapeziometacarpal joint (TMC) because it connects the trapezium to the first metacarpal bone, plays an irreplaceable role in the normal functioning of the thumb.The movements of the first CMC are limited by the shape of the joint, by the capsulo-ligamentous complex surrounding the joint, and by the balance among involved muscles.

In this articulation the movements permitted are flexion and extension in the plane of the palm of the hand, abduction and adduction in a plane at right angles to the palm, circumduction, and opposition.

It is by the movement of opposition that the tip of the thumb is brought into contact with the volar surfaces of the slightly flexed fingers. This movement is effected through the medium of a small sloping facet on the anterior lip of the saddle-shaped articular surface of the greater multangular (trapezium). The flexor muscles pull the corresponding part of the articular surface of the metacarpal bone on to this facet, and the movement of opposition is then carried out by the adductors.Flexion of this joint is produced by the flexor pollicis longus and brevis, assisted by the opponens pollicis and the adductor pollicis.Extension is effected mainly by the abductor pollicis longus, assisted by the extensores pollicis longus and brevis.Adduction is carried out by the adductor; abduction mainly by the abductor pollicis longus and brevis, assisted by the extensors.

Fingers The second metacarpal articulates primarily with the trapezoid and secondarily with the trapezium and capitate.The third metacarpal articulates primarily with the capitate,The fourth metacarpal articulates with the capitate and hamate.The fifth metacarpal articulates with the hamate.
The carpometacarpal joints of second through fifth digits are arthrodial. The movements permitted in the second through fifth carpometacarpal joints most readily observable in the (distal) heads of the metacarpal bones. The range of motions in these joints decrease from the fifth to the second CMCs.

The second to fifth joints are synovial ellipsoidal joints with a nominal degree of freedom (flexion/extension). The second and third joints are essentially immobile . These two CMC provide the other three CMCs with a fixed and stable axis. While the mobility of the fourth CMC joint thus is perceptible, the first joint is a saddle joint with two degrees of freedom which except flexion/extension also enable abduction/adduction and a limited amount of opposition. Together the movements of the fourth and fifth CMCs facilitates for their fingers to oppose the thumb.

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. 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.

It permits movements in three planes - extension/flexion, ulnar deviation/radial deviation, and pronation/supination - and allows complex patterns of motion under significant strain.
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).