Wrist Complex

Question 1

shoulder function in wrist complex

Answer 1

base of support
-provides a stable base onto which to move the arm

Question 2

elbow function in wrist complex

Answer 2

dictates the distance my hand will be from object of interest

Question 3

forearm function in wrist complex

Answer 3

adjustment of hand position

Question 4

carpal joints function in wrist complex

Answer 4

length tension changes
-influence length-tension relationship of the long forearm muscles that move our fingers

Question 5

describe organization of the carpal bones

Answer 5

-proximal row
-distal row

Question 6

proximal row carpal bones

Answer 6

-scaphoid
-lunate
-triquetrum
-pisiform

Question 7

distal row carpal bones

Answer 7

-trapezium
-trapezoid
-capitate
-hamate

Question 8

shape of carpal tunnel

Answer 8

arched

Question 9

what ligaments form arch of carpal tunnel

Answer 9

-transverse carpal ligament
-intercarpal ligaments

Question 10

radiocarpal joint

Answer 10

joint between radius + proximal row of carpals

Question 11

describe concave/convex of radiocarpal joint

Answer 11

-proximal row of carpals is concave
-distal row of carpals is convex

Question 12

do any muscles act solely on radiocarpal joint

Answer 12

no
-so, movement is influenced by activity of muscles that attach in different places
-ex: extensor carpi muscles attach to distal row of carpals + pull on distal row of carpals/metacarpals + move those structures first, then the proximal row of carpals will be moved on the radius

Question 13

midcarpal joint

Answer 13

located between the proximal + distal rows of the carpal bones
-anatomically separate from radiocarpal joint

Question 14

configuration of midcarpal joint

Answer 14

concave-convex-concave confirguration
-shape means these carpals can’t move medially/laterally very well
-aka can’t get a lot of movement to radial side of capitate or ulnar side of hamate due to shape

Question 15

describe movement of wrist extension from flexion

Answer 15

1ST PART OF MOVEMENT- distal carpals glide on proximal carpals in the same direction as motion
* recall that wrist extensor muscles attach to metacarpals distal row, so when I begin to extend my wrist, the first thing that moves is the distal row of metacarpals -> wrist extensors pull distal row of carpals to dorsal side of hand

2ND PART OF MOVEMENT- in neutral, capitate (distal row) + scaphoid (proximal row) come into close packed position
* stable now
* as wrist extensors continue to pull, they will pull capitate into scaphoid, which starts moving on the radius

3RD PART OF MOVEMENT- scaphoid + distal row now glide on lunate + triquetrum

Question 16

wrist extension from flexion- describe at 45 degrees of extension

Answer 16

at 45 degrees of extension, the scaphoid + lunate are in a close-packed position
-all carpals now function as a unit

Question 17

wrist extension from flexion- extension is completed from what

Answer 17

motion of proximal carpal row on radius + TFC
-proximal row of carpals presents convex surface to radius
-so, as I’m extending, the carpals will roll to dorsal side but the proximal row will slide to palmar side

Question 18

wrist extension from flexion- describe closed-packed position of the wrist

Answer 18

full extension

Question 19

describe going into full wrist flexion from extension

Answer 19

opposite of wrist extension from flexion
-proximal row will roll down + glide up
-scaphoid + lunate will become loose-packed so now it is the distal row on the scaphoid
-once I get to neutral, things unlock + it becomes the distal row now going down into the palmar surface that slides down

Question 20

describe roll/glide of proximal carpals on radius during wrist extension

Answer 20

proximal row of carpals
-slides towards us
-rolls away from us

Question 21

describe radial deviation

Answer 21

-distal row moves on proximal row
-the 2 rows lock together for motion of proximal row on radius + radioulnar disk in an ulnar direction

additional explanation:
-flexor/extensor carpi radialis pulls carpals in radial direction trying to radially deviate
-because of its shape, capitate will bang into scaphoid + they will lock together very quickly to act as a single block of carpals moving on the radius
-proximal row is convex, so the whole hand + carpals will roll to radial side + glide to ulnar side

Question 22

in full radial deviation…

Answer 22

both carpal joints are in the close-packed position

Question 23

describe ulnar deviation

Answer 23

-distal row moves ulnarly until limited by ligaments
-hamate is pulled proximally (toward ulnar border), spreading the proximal row + moving them radially -> as this happens, becomes loose-packed + more spread out
-ligaments limit the motion

Question 24

ulnar/radial deviation has more variaibility

Answer 24

ulnar deviation
-because moves into a loose-packed position, more DOF

Question 25

describe how ulnar deviation has more variability

Answer 25

carpals can slide on top of eachother as you move towards ulnar side

Question 26

in ulnar deviation, the proximal/distal row moves first

Answer 26

distal row -similar to radial deviation in this aspect -because that is where extensor/flexor carpi ulnaris are attached

Question 27

what limits the motion of ulnar deviation

Answer 27

ligaments

Question 28

also read class notes from 9/17 on this information