The Wrist- Palastanga Flashcards
What joints functionally comprise the wrist
Intercarpal, midcarpal and radiocarpal articulations
Classification of the radiocarpal joint
Synovial ellipsoid
Articular surfaces of the radiocarpal (rc) joint
Distal radius and articular disc with scaphoid, lunate and triquetral of the proximal row of carpals
When combined with supination/ pronation at the forearm the hand appears to move as
A ball and socket
Why is there great inherent stability at the wrist/ hand
Because of the separation of the 3 axes about which movement occurs
Also because of the flexor retinaculum and many tendons crossing the region
Describe the joint capsule of the rcj
Fibrous completely enclosing the joint
Thickened anteriorly and posteriorly and hence strengthened in these regions
Blends with collateral carpal ligaments medially and laterally
Capsular ligaments of the rcj
Dorsal radiocarpal
Palmar radiocarpal
Palmar ulnocarpal
Functions of the capsular ligaments of the rcj
Strengthen the capsule and determine that the hand follows the radius in its movements and displacements
Are taut in flexion and extension
Other supporting ligaments of the rcj
The collateral ligaments
Radial collateral carpal ligament is taut and limits adduction
Ulnar collateral carpal ligament is taut and limits abduction
Movements possible at the rcj
Flexion/ extension
Abduction/ adduction
Describe flexion/ extension at the rcj
Occur about a transverse axis more or less in the sagittal plane
Flexion freer than extension
ROMs of flexion/ extension at the rcj
Flexion max 50d
Extension max 35d
Describe abduction/ adduction at the rcj
Also referred to as radial and ulnar deviation respectively
Movement of proximal row of carpals in relation to the distal radius
Which movement of ab/adduction at the rcj is more limited and why
Abduction/ radial deviation is more limited due to the further extension of the radial styloid process compared to the ulnar styloid process
ROMs of ab/adduction of the rcj
Abduction/ radial deviation = 7d
Adduction/ ulnar deviation = 30d
How are the carpal bones arranged
Into 2 rows, proximal and distal, between which lies the midcarpal joint
Classification of the intercarpal joints (icj)
Most are plane synovial and have various ligaments between them permitting very little movement
Articular surfaces of the midcarpal joint (mcj)
Laterally - trapezium and trapezoid with scaphoid forming a slight convexity
Medially/ centrally - capitate with scaphoid and lunate, also hamate with lunate and triquetral forming a slight concavity
Describe the joint capsule of the mcj
Composed primarily of irregular fibrous bands running between the 2 rows of bones
Anteriorly and posteriorly these fibres constitute the palmar and dorsal inetrcarpal ligaments
Describe the synovial cavity of the mcj
Is large and complex extending between the bones and may be interrupted by interosseous ligaments
Ligaments associated with the mcj
Palmar intercarpal ligament is the largest
Dorsal intercarpal
Radial and ulnar collaterals
Movements possible at the midcarpal joint
Flexion/ extension
Abduction/ adduction
Which movement of flexion/ extension if freer at the mcj
Extension
opposite to the rcj
ROMs of flexion/ extension of the mcj
Flexion 35d
Extension 50d
Abduction/ adduction at the mcj is accompanied by what
Torsion between the 2 rows of bones
ROM of ab/adduction at the mcj
Abduction 8d
Adduction 15d
What is the principal structure responsible for maintaining the transverse arch of the 2 rows of carpal bones
The flexor retinaculum
The rows of carpals + the flexor retinaculum form what important structure
The carpal tunnel
What passes through the carpal tunnel
MEDIAN nerve
Tendons of flexor pollicis longus, flexor digitorum profundus, flexor digitorum superficialis
A fall onto an outstretched hand may result in a dislocation where
Radiocarpal and/or midcarpal joints
What is important about the movements occurring at the wrist
Movements occurring at the radiocarpal and midcarpal joints are happening at the same time so combine to give the wrist its full ROM
What is the total range of flexion/ extension possible at the wrist
85d in each direction
Flexion - 50d at rcj and 35 at mcj
Extension - 35d at rcj and 50d at mcj
Where does the axis of flexion/ extension of the wrist fall through
The head of the capitate
When is flexion least effective and what limits this movement
Limited by tension in the extensor tendons and is greatly reduced if fingers are flexed
I.e. wrist flexion is greatest when fingers are extended
What are the total ROMs for ab/adduction at the wrist complex
Abduction - 15d
Adduction - 45d
Muscles producing wrist flexion
Flexors carpi radialis and ulnaris
Palmaris longus
Flexor digitorum profundus/ superficialis
Flexor pollicis longus
Muscles producing wrist extension
Extensors carpi ulnaris and radialis longus and brevis Extensor digitorum Extensor indicis Extensor digiti minimi Extensor pollicis longus
Muscles abducting the wrist
Flexor carpi radialis
Extensor carpi radialis longus and brevis
Muscles adducting the wrist
Flexor carpi ulnaris
Extensor carpi ulnaris
What happens at the wrist during flexion/ extension of the fingers
The carpal flexors/ extensors fix the wrist preventing loss of digital power
n.b. grip is not as strong when wrist strongly extended or flexed
Why is the wrist slightly extended when powerful grip is needed
This extension stretched the digit flexors allowing a powerful grip
This is the position the wrist is fused in to allow the maintenance of grip power
