wrist joints Flashcards
primary role of the wrist
control the length-tension relationship
permit fine adjustment of grip
wrist complex is composed of how many joints
2 compound joints
when the wrist cant do its job
nothing can do its job
nothing can compensate for the wrist
radiocarpal joint
articulation of the radius and radioulnar disk proximally w/ the scaphoid, lunate and triquetrum distally
does the ulnar articulate with the carpal bones
NO
separated by the radioulnar disk
the proximal surface is _______
biconcave
radius and the disk
parts of the proximal surface
lateral radial facet
medial radial facet
radioulnar disk
lateral radial facet
articulated w/ the scaphoid and accounts for approximately 46% of the articular surface
medial radial facet
articulates with the lunate and accounts for approximately 43% of the articular surface
radioulnar disk
articulates w/ the triquetrum and accounts for approximately 11% of the articular surface
which way does the biconcave surface face
volarly (palmarly) and ulnarly
tilted down and out
allows for more flexion than extension and more ulnar deviation than radial deviation
what bony architecture also limits motion in the wrist
dorsal lip on the radius –> limited extension ROM
radial styloid process extends further than ulnar styloid –> radial deviation is limited
midcarpal joint
articulation b/w scaphoid, lunate and triquetrum proximally
trapezium, trapezoid, capitate and hamate distally
considered a functional rather than an anatomic unit
no single continuous articular surface
midcarpal joint articular surface has
2 parts
medial joint surface
radial joint surface
medial joint surface
articulation of lunate and triquetrum proximally w/ the capitate and hamate distally
lunate and triquetrum are concave (proximal surface)
hamate and capitate are convex (distal surface)
how does the medial joint surface move
distal moves on proximal surface
bone motion and roll in the same direction
glide opposite direction
lateral joint surface
articulation of scaphoid proximally with the trapezium and trapezoid distally
scaphoid is convex
trapezium and trapezoid are concave
how does the lateral joint surface move
bone motion, roll and glide in the same direction
intercarpal joints
articulation b/w individual carpal bones
play a small role in overall wrist movement
these joints primarily glide on each other
what kind of joint is the radiocarpal joint
bi-axial joint with 2 degrees of freedom of motion
movements of the radiocarpal joints
allows for flexion and extension in the sagittal plane around a frontal (x-axis)
allows for radial deviation in the frontal plane around a sagittal (z) axis
allows for circumduction (combination of all the movements), not a true degree of freedom
what is the midcarpal joint
a condyloid joint with two degrees of freedom
what motions does the midcarpal joint allow
allows for flexion and extension in the sagittal plane around a frontal (x-axis)
allows for radial deviation in the frontal plane around a sagittal (z) axis
arthrokinematics of radiocarpal joint
convex moving on concave
biconvex (scaphoid, lunate and triquetrum) moving on biconcave (radius and disk)
radiocarpal flexion arthrokinematics
bone motion and role –> anterior
glide –> posterior
radiocarpal extension arthrokinematics
bone motion and roll –> posterior
glide –> anterior
radiocarpal joint radial deviation arthrokinematics
bone motion and roll –> radial direction
glide –> ulnar direction
radiocarpal joint ulnar deviation arthrokinematics
bone motion and roll –> ulnar direction
glide –> radial direction
midcarpal joint arthrokinematics
medial surface is convex (hamate and capitate) moving on concave (lunate and triquetrum)
bone motion and roll same direction
glide opposite direction
convex moving on concave
flexion of the midcarpal arthrokinematics (medial)
bone motion and roll –> anterior
glide –> posterior
extension of the midcarpal arthrokinematics (medial)
bone motion and roll –> posterior
glide –> anterior
radial deviation of the midcarpal joint (medial) arthrokinematics
bone motion and roll –> radial direction
glide –> ulnar direction
ulnar deviation of the midcarpal joint (medial) arthrokinematics
bone motion and roll –> ulnar direction
glide –> radial direction
lateral surface of midcarpal joint surface
concave (trapezoid and trapezium) moving on convex (scaphoid)
glide, bone motion and roll are in the same direction
lateral midcarpal joint flexion
everything goes anterior
lateral midcarpal joint extension
everything goes posterior
lateral mid carpal joint RD
everything goes radially
lateral midcarpal joint UD
everything goes ulnarlly
how do the midcarpal and radiocarpal joints move
no muscles that exert direct force at the radiocarpal joint
this joint acts as a mechanical link b/w the radius and the distal carpals (b/c these areas do have muscle force actually applied)
motions at the wrist are caused by a combination of active and passive forces
extension of the wrist
events occurs from full flexion to full extension
full flexion
neutral flex/ext
neutral to 45 degrees of extension
45 degrees of extension towards full extension
full flexion (first step in extension)
initiated as the distal carpal row (capitate, hamate, trapezoid and trapezium) glide on the relatively fixed proximal row
wrist extensors then contract –> midcarpal joint moves –> distal row glides onto the proximal row
neutral flexion/extension (step 2 of extension)
the capitate and scaphoid link together into a close packed position via ligamentous tension
the scaphoid is now considered a part of the distal carpal row
as the wrist continues to move, the scaphoid will move with the distal carap row
neutral to 45 degrees of extension (3rd step to extension)
this distal carpal row and the linked scaphoid move on the relatively fixed lunate and triquetrum
still midcarpal joint motion
45 degrees of extension towards full extension (4th step)
the scaphoid and lunate and brought into a close-packed position
this unites all the carpals and causes them to function as a solid unit
all the carpal will now move together as one unit
full extension (last step of extension)
wrist extension is completed as the proximal articular surface of the carpals moves as a solid unit on the radius and radioulnar disk
the entire wrist complex is in a close packed position when full extension is reached
normal ROM for extension
0-70 or 80 degrees
35 degrees from radiocarpal joint
40-45 degrees from midcarpal
axis of movement for extension
changes throughout the ROM
what limits extension
anterior capsule
volar radiocarpal ligament
ulnar-carpal ligament
what happens if there is a tear or trauma to the wrist
none of this process of extension will happen
muscle has to work harder d/t no assistance from the ligaments
ex: tennis elbow
wrist flexion
sequence is reversed from extension
wrist flexors contract to move radiocarpal joint –> midcarpal joint
progress to an unlocked (open-packed position)
normal ROM for flexion
0-85 degrees
axis of movement for flexion
changes throughout the ROM
what limits flexion
posterior capsule
dorsal radiocarpal ligament
radial deviation sequence
distal carpal row moves radially on the proximal row (midcarpal joint)
as motion continues, the carpals will lock together d/t ligamentous tension and begin to move as a single unit
this single unit will slide ulanrly on the radius and radioulnar disk
scaphoid and lunate will flex, while the distal row will extend, to accommodate for narrowing space b/w trapezium and the radial styloid process
normal ROM RD
0-25
axis of movement RD
through the capitate in anterior to posterior direction
what limits RD
ulnar collateral ligament
medial capsule
bony contact
ulnar deviation sequence
distal carpal row moves ulnarly until checked by ligaments
simultaneously the hamate is pulled proximally, causing the proximal carpals to spread and slide radially until checked by the radial ligaments
the scaphoid and lunate will extend while the distal carpals will flex
normal ROM UD
0-45
axis of movement UD
through the capitate in anterior to posterior direction
what limits UD
radial collateral ligament
lateral capsule
what joint is most important
MIDCARPAL JOINT!!!!!
what gives us motion
not only active forces that gives us motion, but also passive movement by the ligaments so that other muscles can do their jobs
no active muscles working on the radiocarpal joint
linked by ligamentous tension
