Please enable JavaScript.
Coggle requires JavaScript to display documents.
Functions of the Wrist Complex - Coggle Diagram
Functions of the Wrist Complex
Movements of the radio carpal
and mid carpal joints
The wrist is considered as a 3 segment linkage and the proximal row of
carpals act as an intercalated segment
Proximal row of carpals functions as a
mechanical link between the radius and the distal carpals
No muscular forces are directly applied to the proximal row articular surfaces
When a compressive force is applied,
the proximal carpal row will move towards
the opposite direction
from the above and below segment
Application of compressive muscular extension at the wrist complex will cause
an unstable scaphoid to collapse into flexion
while the distal row is still extended
Scaphoid in such circumstances
will be stabilized by the
passive ligamentous connections
and the movement of adjacent carpals
The 3 bones of the proximal row
do not move as a unit
and results in a
counterrotation movement
Under compression
scaphoid flexes
the lunate and triquetrum extends
because of the ligamentous connections
the movement is translated as
a flexion and pronation of the whole row.
Flexion/Extension of the wrist
Capitate as the center of rotation
for the Coronal axis movements
Scaphoid moves the most
and lunate moves the least
from the proximal row
during flexion and extension
scaphoid-capitate,
scaphpoid-lunate and
radio-scaphoid
motion happens
A sequence of events occur for the relative motions of the various segments of wrist complex
From full flexion to full extension
Distal carpal row moves on the proximal row
Initiated by the wrist extensors
The scaphoid and distal row
move on the
lunate/triquetrum
The carpals move as a unit
on the radius and TFC
to achieve full extension
From full extension to full flexion
the reverse sequence would occur
Radial/Ulna deviation of the wrist
The proximal row displays a reciprocal motion
with radial and ulnar deviation
In Radial deviation
Carpals move ulnarly on the radius
Simultaneous flexion of proximal carpals
with extension of distal carpals
Radiocarpal and midcarpal joints
are in close packed position
at full deviation
The magnitude of scaphoid flexion
during radial deviation
was related to
the laxity of ligaments
More laxity of the ligaments meant
that more flexion/extension by scaphoid
and less deviation
Laxity is more common in women
In Ulnar deviation
Carpals move radialy on the radius
Simultaneous flexion of distal carpals
with extension of proximal carpals
ROM of radial and ulnar deviation is greatest when the hand is in neutral position
(flexion/extension)
Wrist instability
Injury to
ligaments attached to the scaphoid or lunate
will impair the stabilization
of the lunate and scaphoid
Scaphoid behaves as an unconstrained segment
Collapse into flexion
on the volarly inclined surface
of the distal radius
Base of the scaphoid
slides dorsally on the radius
and subluxes
Released from scaphoid stabilization,
the lunate and triquetrum together
act as an unconstrained segment
Extend together and
forces the distal row to flex
with the forces applied from musculature
The dorsal carpals will glide dorsally
on the lunate and triquetrum,
making the unconstrained segment extension more prominent
This creates a zigzag pattern known as intercalated segmental instability
Scaphoid – lunate/triquetrum – distal carpal row
Dorsal intercalated segmental instability (DISI)
Lunate released from fixed scaphoid
Lunate extends on the radius
Capitate moves in the opposite direction (flexion) on top of the lunate
Scapholunate advanced collapse (SLAC wrist)
Progressive degenerative problem that rises from an untreated DISI
Radioscpahoid joint
shows more degenerative changes when compared to
radiolunate articulation
Radiolunate articular surface
has a more spherical configuration,
force distribution is better across the facets
Volar intercalated segmental instability (VISI)
Injury to the ligamentous union
between the lunate and triquetrum
Lunate is no longer linked to the triquetrum
Lunate and scaphoid
fall into flexion on the radius
Triquetrum and distal carpal row extended
Also known as the Ulna perilunate instability
Not as common as DISI