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POTH 225: BIOMECHANICS > lecture 11: wrist and hand > Flashcards

lecture 11: wrist and hand Flashcards

1
Q

what carpal bones are in the proximal row

A

scaphoid. lunate, triquetrum, pisiform

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2
Q

what carpal bone sits on the triquetrum

A

pisiform

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3
Q

what carpal bones are in the distal row

A

trapezium, trapezoid, capitate, hamate

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4
Q

true or false: the capitate bone is part of the proximal roq

A

false, the distal row

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5
Q

what carpal bone sits at the base of the thumb

A

the trapezium

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6
Q

which carpal bone is the keystone/main anchor of the carpus

A

capitate

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7
Q

be able to name the carpal bones and if they are in the distal or proximal row

A
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8
Q

why is there such a tight fit of the carpal bones

A

to allow for stability

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9
Q

what are the smoothest lines of the wrist called

A

gilula lines

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10
Q

what percentage of force transmission occurs at the distal radius in the normal wrist

A

80%

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11
Q

true or false: the scaphoid has 2 regions

A

false, 3 regions

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12
Q

what are the 3 regions of the scaphoid

A

distal pole
proximal pole
wasit

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13
Q

what is another name for the scaphoid bone in the wrist

A

navicular

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14
Q

what region of the scaphoid is poorly vascularized

A

proximal pole

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15
Q

since the proximal pole of the scaphoid is poorly vascularized, what is it susceptible to

A

avascular necrosis

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16
Q

how is the scaphoid frequently fractured

A

by fall on hyperextended radially deviated wrist

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17
Q

true or false: the scaphois is frequently fractured by fall on hyperextended ulnar deviated wrist

A

false, radially

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18
Q

where can you palpate the scaphoid

A

snuff box

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19
Q

what bone is considered an important stabilizer of the carpus (not the scaphoid)

A

lunate

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20
Q

what carpus bone has very little movement

A

luante

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21
Q

true or false: the lunate has very limited movement

A

true

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22
Q

true or false: the scaphoid bone is the only bone vulnerable to avascular necrosis

A

false , the lunate as well

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23
Q

what is keinbocks disease

A

condition where the blood supply to one of the small bones in the wrist, the lunate, is interrupted.

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24
Q

true or false: the lunate is also vulnerable to avascular necrosis

A

true (keinbocks disease)

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25
Q

what are the regions of the hamate

A

proximal pole and hook and body

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26
Q

what carpus bone is the site of attachment of the flexor retinaculum

A

hammate

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27
Q

true or false: the capitate is the site of attachment of the flexor retinaculum

A

false, the hamate is

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28
Q

where can you palpate the hamate

A

near base of pinky

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29
Q

what is the bone that is saddle shaped at the base of the thumb

A

trapezium

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30
Q

what two carpus bones contribute to the anterior orientation of the thumb

A

trapezium and scaphoid

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31
Q

the trapezium and the scaphoid together contribute to what and why is that important

A

to the anterior orientation of the thumb
(important for grasp)

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32
Q

what is the larges carpal bone

A

capitate

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33
Q

where is the capitate located

A

orientated at the base of the long finger

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34
Q

what bone is the stable base for the index finger

A

trapezoid

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35
Q

what bone is located at the base of the index finger important for pimch

A

trapezoid

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36
Q

true or false: the capitate bone is important for pinch

A

false, the trapezoid

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37
Q

what carpal bone articulates with the fibrocartiligenous disc and pisiform

A

triquetrum

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38
Q

true or false; the pisiform is a sesamoid bone

A

true

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39
Q

what are the 3 main joints of the wrist

A

distal radioulnar joint (DRUJ)
radoiocarpal joint
mid-carpal joint

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40
Q

what is the force transmission at the radius-carpus during radial deviation

A

87%

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41
Q

what is the force transmission at the ulna-carpus during rotatio

A

37%

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42
Q

what is the force transmission at the mid carpal (neutral) of the scaphotrapezium-trapezoid

A

31%

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43
Q

what are the bony parts of the radoiocarpal joint

A

radius and the proximal carpal row

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44
Q

in the radoiocarpal joint, the radius articulates with what carpal boens

A

scaphoid and lunate

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45
Q

what motions does the radoiocarpal joint contribute to

A

flexion, extension and radial-ulnar deviation

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46
Q

what is the primary function of the distal radioulnar joint

A

forearm pronation and supination

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47
Q

what does the distal radioulnar joinnt facilitate

A

load transmission between radius-hand and ulna

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48
Q

true or false: the radio carpal joint facilitates load transmission between radius-hand and ulna

A

false, the distal radioulnar joint does

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49
Q

extrinsic ligaments of the wrist are orientaed towards where

A

midline

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50
Q

what does it mean for a wrist ligament to be extrinsic

A

from radius/ulna to carpal bones
(oriented towards the midline)

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51
Q

are the intrinsic or extrinsic ligs v shaped

A

extrinsic

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52
Q

are the volar ligaments or dorsal ligaments of the extrinsic ligaments on the wrist stronger

A

volar ligaments are stronger

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53
Q

what is the function of the extrinsic wrist ligaments

A

stabilize the carpus during extension (force transmission during weight bearing)

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54
Q

what are the static stabilizers of the DRUJ

A

TFCC
ECU (including sheath)
interosseous membrane

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55
Q

what are the dynamic stabilizers of the DRUJ

A

pronator quadratus
pronator teres
biceps brachii (inserion tuberosity of the radius and deep fascia of FA)
supinator (intertion lateral, proximal shft of radius)

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56
Q

what are the 4 things that make up the TFCC

A

dorsal radioulnar ligament (DRUL)
palmar radioulnar ligament (PRUL)
ECU
articular disk

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57
Q

what does the article disk of the TFCC function

A

increases the surface area of distal ulna and shock absorption

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58
Q

what are the 4 functions of the TFCC

A

stabilization of the DRUJ and ulnar side of carpus
cushion ulna on carpus
allows axial loading of ulna on forearm
increases articular surface of carpus

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59
Q

true or false: The TFCC stabilizes the DRUJ and radial side of the carpus

A

false, ulnar

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60
Q

where is the mid carpal joint formed

A

between two carpal rows (b/w distal and proximal)

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61
Q

what does the mid carpal joint contribute to

A

flexion
extension
radial-ulnar deviation

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62
Q

how is the mid carpal joint stabilzied

A

stabilization via ligaments and capsule

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63
Q

accord to garcia ellas, 2013, which joint is more important: the mid carpal or radoiocarpal joint

A

midcarap

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64
Q

true or false: the proximal row has no tendinous inserions

A

true

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65
Q

where does wrist mvovment start

A

distal row of carpus

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66
Q

explain wrist movement and how mid carpal is more important that radoiocarpal joint

A

proximal row has no tendinous insertions

wrist movement starts at distal row of carpis

movement pulls mid carpal ligaments taut, creates a compressive load and moves proximal row

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67
Q

what is the orientation of the intrinsic ligaments of the wrist

A

transverse orientation

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68
Q

what does it mean to be an intrinsic ligament of the wrist

A

carpal to carpal

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69
Q

what are the two important intrinsic ligaments

A

scapholunate (interesses) ligament
lunotriquetral interosseous ligament

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70
Q

in an xray, if there is space between the scaphoid and lunate, what ligament is ruptured

A

scapholunate

71
Q

what is the most common wrist ligament injury

A

SL ligament (scapholunate)

72
Q

true or false: The SL lig rupture is most common wrist ligament injury

A

true

73
Q

what is a common cause of carpal instability and the most common wrist lig injury

A

SL ligament rupture

74
Q

true or false: there is higher SL lig tensile force in flexion

A

false, extension

75
Q

in what position is there higher SL ligament tensile force

A

extension

76
Q

what is the common name of an Scapholunate ligament tear

A

terry thomas sign (space between scaphoid and lunate)

77
Q

what are the two types of intrinsic ligament dissociation

A

volar
(volar intercalary segment instability(

dorsal
(dorsal intercalary segment instability)

78
Q

explain volar intercalary segment instability

A

L-T ligament rupture (plus dorsal radoiocarpal and volar radiocarpal)
=lunate points in a volar direction

79
Q

explain dorsal intercalary segment instability

A

SL ligament rupture (plus scaphotrapeziumtrapezoid or dorsal inter carpal)
-lunate points in a dorsal direction

80
Q

VISI is associated with LT or SL ligament rupture

A

LT

81
Q

DISI is associated with LT or SL ligament rupture

A

SL ligament

82
Q

in the study of incidence of carpal instability two years after fall on outstretched hand, what percentage had clinical evidence of carpal instability

A

44%

83
Q

in the study of incidence of carpal instability two years after fall on outstretched hand, 44% had clinical evidence of carpal instability, of those 44% how many had scapho-lunate dissocaiteion

A

24%

84
Q

what happens if you get an untreated scapholunate ligament injury

A

scapholunate advanced collapse (SLAC wrist)
=capitate will descend and fill in the empty spot

85
Q

are ligaments the only wrist stabilizers

A

no , we are able to surpass the tensile strength of wrist ligaments without rupture

86
Q

true or false: scapholunate ligament is more than just a passive restraint

A

true

87
Q

explain how the scapholunate ligament is more than just a passive restraint

A

there are mechanoreceptors in ligaments that signal joint perturbation and influence surrounding muscles
=reactions are protection

88
Q

the centre of rotation in the wrist goes through what bone

A

capitate

89
Q

with a distal radius fracture, which movement would be more problematic

A

extension because it has a greater contribution of radiocapral

90
Q

during flexion, explain the joint contribution of the radoiocarpal and mid carpal

A

40% radiocapral
60% mid carpal

91
Q

during extension, explain the joint contribution of the radoiocarpal and mid carpal

A

33.5% mid carpal
66.5% radoiocarpal

92
Q

there is a higher contribution from radoiocarpal or midcarpal during extension

A

radoiocarpal

93
Q

explain the movement of the carpals during flexion

A

distal and proximal carpal rows both move into flexion

94
Q

explain the movement of the carpals during extension

A

distal and proximal carpal rows both move into extension

95
Q

explain the symbolic movement of wrist flexion and extension

A

carpal rows act like 2 cylinders rolling in the same direction

96
Q

explain the carpal kinematics during radial deviation

A

1) proximal row flexes and translates ulnarly
2) lunate pronates
3) triquetrum rides proximally and dorsally on hamate

97
Q

explain the carpal kinematics during ulnar deviateion

A

1) proximal row extends and translates radially
2) lunate supinates
3) triquetrum rides distally and volarly on hamate

98
Q

a terry thomas sign is a radiographic indicator of what

A

scapholunate ligament rupture

99
Q

there is greater mobility with what finger bones

A

with ring and little finger metacarpals

100
Q

why is there different metacarpal lengths

A

cascade/convergence
=natural cascade towards base of thumb

101
Q

what are the 3 arches of the hand

A

fixed transverse proximal arch
movile distal transverse arch
longitudinal arch

102
Q

where is the fixed transverse proximal arch

A

mid point = capitate

103
Q

the proximal transverse arch is fixed or movile

A

fixed

104
Q

the distal transverse arch is fixed or mobile

A

mobile

105
Q

what is the midpoint of the mobile distal transverse arch

A

3rd metacarpal

106
Q

which is mobile: the distal or proximal transverse arch

A

distal

107
Q

along what metacarpal does the longitudinal arch of the hand lie

A

3rd metacarpal

108
Q

since the metacarpals are different lengths what does that mean

A

there is a volar arch

109
Q

what type of joint is the MCP (in fingers)

A

condylyar

110
Q

what are the movements possible for MCP

A

flexion/extension
abduction/adduction

111
Q

what type of joint are the PIP and DIP joints

A

hinge

112
Q

what are the movements possible at the PIP and DIP joints

A

flexion and extension

113
Q

true or false; the finger joints are synovial

A

true

114
Q

what are the finger ligaments

A

ulnar and radial collateral ligaments (cord and accessory(

volar (palmar plate)

115
Q

in which position are the collateral ligaments of the finger most taut

A

PIP and DIP closed pack position is in full extension
collaterals at MCP are tight when flexion

116
Q

what is the MCP ROM (in fingers) during flexion extension

A

flexion: 90
extension 0

117
Q

what is the PIP ROM during flexion extension

A

flexion: 100
extension: 0

118
Q

what is the DIP ROM during flexion

A

flexion: 80
extension 00

119
Q

true or false: the MCP gets 100 degrees of flexion

A

false, the MCP gets 90
the PIP gets 100

120
Q

which joint has most flexion ROM: the MCP< PIP or DIP

A

PIP

121
Q

according to evans, whas is the minimal DIP flexion needed

A

70

122
Q

thumb makes up what percentage of hand function

A

60%

123
Q

what type of joint is the MCP joint at the thumb

A

biaxial joint

124
Q

what are the motions possible at the MCP joint of the thumb

A

flexion/extension
abduction/adduction

125
Q

what type of joint is the IP joint at the thumb

A

hinge joint

126
Q

what are the movements possible at the IP joint of the thumb

A

flexion/exnesion

127
Q

what type of joint is the CMC of the thumb

A

saddle joint

128
Q

what movements are possible at the CMC joint of the thumb

A

flexion/extension
abduction/adduction
circumfuction and opposition

129
Q

what is the normal ROM in the MCP joint of the thumb

A

flexion: 55 degrees
hyperextension: 10 degrees

130
Q

what is the normal ROM of the IP joint of the thumb

A

flexion: 80
extension: 0

131
Q

what is the normal ROM of palmar abduction of the thumb

A

45 degrees

132
Q

what are the dynamic stabilizers of the CMC joint of the thumb

A

ADD
APD
OPP
FPB
APL
FPL
EPB
EPL

133
Q

what are the static stabilizers of the CMC

A

16 ligaments
most important arte palmar oblique (beak) ligament and dorsoradial ligament

134
Q

with more lateral pinch force, what happens do the CMC joint contract force

A

it increases

135
Q

what can happens with erosive chagnes with osteoarthritic

A

CMC subluxation

136
Q

what is shoulder sign indicative of

A

dorsal radial dislocation of 1st MC (CMC)
tilting in dorsal radial direction

137
Q

what are the extrinsic musculotendinous structure flexors

A

flexor digi superficualis (FDS)
flexor digi profundus (FDP)
flexor pol longus (FPL)
palmaris longus (PL)

138
Q

what position would allow for optimal differential glide of FDS and FDP

A

hook fist
=flexion of PIP and DIP with no flexion of MCP

139
Q

what position would allow for optimal glide of FDS

A

straight fist
=fexion of MCP and PIP but extension of DIP

140
Q

what position would allow optimal glide of FDP

A

full fist (full flexion)

141
Q

true or false: the full fist allows optimal glide of the FDS

A

false, FDP

142
Q

hook fist allows optional differential glide of what

A

FDP FDS

143
Q

straight fist allows optimal glide of what

A

FDS

144
Q

full fist allows optimal flide of what

A

FDP

145
Q

what are the extrinsic musculotendinous structures for extension and abduction

A

extensor digitorum communis (EDC)
indiex proprius
extensor digiti mini
extensor pollicis longus/brevis
abductor pollicis longus

146
Q

what fingers have individual extensor tendons

A

indépendant active extension of the index and little fingers

147
Q

true or false: active extension of the long and ring fingers is difficultt when the MCP joints of index and little fingers are flexed

A

true

148
Q

what is the juncture tendinae

A

the tendons of the extensor digital to the fingers are connected to one another by the junctura tendinae

149
Q

what is the function of the juncturae tendinae

A

increase extension to individual fingers

if one of two fingers passively flexed at MP, pulls EDC of other fingers along

150
Q

what muscles make up the thenar eminence

A

flexor pollicus brevis
opponens pollicus
abductor pollicis brevis
adductor polices

151
Q

what muscles make up the hypothenar eminence

A

flexor digiti minimi
opponents digiti minimi
abductor digiti minimi

152
Q

what are the intrinsics of the hand

A

lumbricals and itnerosseus structures

153
Q

explain the diamond of stack during flexion and extension

A

during flexion, diamondss is larger
during extension, diamond is tighter

154
Q

explain boutineires deformity

A

disruption of central slip insertion (causes slip in the volar direction of the lateral bands)
=PIP flexion and DIP extension

155
Q

why does MP flexion cause IP extension

A

because the lateral slips of the EDC tighten and pull the lateral bands
(flexion of MPs and etension of PIP/DIP)

156
Q

EXPLAIN FINGER movement segment during digital flexion

A

extrinsic FDS initiates flexion at the PIP joint
extrinsic FDP then flexes the DIP joint
intrinsics then flex MP joint

157
Q

explain finger movement segment during digital extension

A

extrinsic EDC extends MP joint
intrinsic lumbricals and interosseus muscles extend PIP and DIP joint

158
Q

explain the tenodesis pattern

A

wirst Extension = finger flexion

wrist flexion = finger extension

159
Q

what are the 3 functions of the retinacular system (flexor retinaculum)

A

prevent bowstringing of flexor tendons
maintains capral arch
optimizes flexor forces

160
Q

what structure forms the roof of the carpal tunnel

A

flexor retinaculum

161
Q

what needs to be cut open in carpal tunnel syndrome surgery

A

flexor retinaculum

162
Q

what is the function of the extensor retinculum

A

functions as a pulley for the extensor tendons
maintains constant moment arm

163
Q

what is the test for DeQuervains tendonitis

A

finklesteins test

164
Q

what is the finklesteins tes

A

to test for dequervains syndrome
=wrist ulnar deviation and thumb flexion

165
Q

what is dequervains syndrome

A

swelling of the tendons that run along the thumb side of the wrist and attach to the base of the thumb
(abductor pollicus longus and extensor polloicus brecvis)

1st dorsal comparement of the extensor retinaculum

166
Q

what is the function of the the digital flexor tendon pulley system

A

prevents bowstringing
=increase torque and decrease excursion

167
Q

how can a patient optimize FDS glide

A

make a straight fist

168
Q

what are the fucntions of the pulley excision

A

there are 4 normal annular bullies facilitate normal flexion

169
Q

what are the 3 most useful pulleys

A

a2, a4 and a3

170
Q

what bands make up the diamond of stack in fingers

A

lateral bands

171
Q

the lateral bands in the finger make up a shape, what is that shape called

A

diamond of stack

172
Q

what three structures contribute to form the lateral and central bands of the fingers

A

EDC (extensor digi)
interossei
lumbricals

173
Q

flexion of MCP and simultaneous extension of PIP/DIP relies mostly on what muscels

A

intrinsics (ex : lumbricals)

POTH 225: BIOMECHANICS (15 decks)

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