Lecture 14: Wrist osteology and Arthrology Final Flashcards
where is listers tubercle
dorsal radius
describe the distal articular surface of the radius
concave in both M-L and A-P with facets in the articular surface
what are the 2 important biomechanical configurations of the wrist
distal end of the radius is 25 deg toward ulna = “ulna tilt”; allows more ulnar dev than radial
palmar tilt = 10 deg allows more flexion than ext of wrist
describe the carpals
proximal row = scaphoid, lunate, triquetrum, and pisiform; loosely joined
distal row = trapezium, trapezoid, capitate, and hamate; tightly bound by ligaments
describe the scaphoid bone
looks like a boat
associated with both carpal rows
undersurface rides on radius
75% is lined with articular cartilahe
cargo area of the scaphoid holds what
head of capitate
scaphoid has synovial joints with how many other carpals
4
describe teh 2 poles of the scaphoid
2 convex poles
proximal articulates with radius; distal with trapezium and trapezoid
small concavity on scaphoid holds what
lunate
where can you palpate the scaphoid tubercle
thenar musculature
most frequent fractured carpal
scaphoid
midway between poles
proximal can develop AVN
what is kienbocks disease
softening of lunate AVN
describe the lunate
moon shaped
central bone in prox row
most unstable carpal due to lack of strong ligaments and no muscle attachments
fits into radius
describe triquetrum
triangular bone
most ulnar just distal to ulna
articular facet that accepts pisiform
describe pisiform
pea shaped
loose articulation with triquetrum
movable/palpable
embedded in FCU tendon
acts as sesamoid
attachment for abd digiti minimi and transverse carpal ligament
describe capitate
largets/central; means head
articulates with 7 bones
articulates with concavity of scaphoid and lunate
well stabilized by stong/short ligaments
joined to 2-4 metacarpal
provides longitudinal stability
describe trapezium
asymmetrical
concave at scaphoid
distal saddle like surface
tubercle = attachment for trans carpal lig
FCR groove
describe trapezoid
small
wedged between capitate and trapezium
firm attachment to 2nd metacarpal
describe hamate
large hooklike process
4th and 5th metacarpals
functional mobility “cupped hand”
attachment for trans carpal lig
what is carpal tunnel
thick fibrous band of connective tissue = trans carpal lig
connected on 4 raised points
attachment site for many intrinsic muscles in the hand and palmaris longus
what 4 raised points is the carpal tunnel attached to
pisiform
hook of hamate
tubercles of scaphoid and trapezium
what is the joint structure of the radiocarpal joint
concave radius and disc and convex scaphoid and lunate
triquetrum contacts with ulnar dev
when is there greatest contact at the radiocarpal joint
at slight ext and ulnar dev
how much force is present at the disc of the radiocarpal joint
20% compressive force
joint structure of mid carpal joints
between proximal and distal rows
continuous capsule
lateral and medial compartmetns; more movement in medial
how many intercapral joints
13
small gliding and rotatory motions
ligaments help disipate force
importance of ligaments of wrist
essential to maintain carpal alignment and transfer forces
stretched ligaments hold muscle produced energy and help with arthrokinematics
mechanoreceptors in ligaments; especially dorsal
describe the fibrous capsule of the hand/wrist
surrounds wrist and distal radioulnar joint
ligaments embedded in capsule
describe what you might see where the TFCC is on a radiograph
looks like empty space
osteokinematics of the wrist
2 degrees of freedom
flx/ext
radial/ulnar dev
what is wrist circumduction
combo of movements; not a 3rd degree of freedom
where is the axis of the wrist
through head of capitate
M-L axis for flexion and extension
A-P for radial/ulnar dev
axis migrates through ROM
Rt of capitate directes osteokinematics of the whole hand
movement of wrist in sagittal plane
130-160 total
flexion = 0-70/85
ext = 0-60/75
greater than normal palmar tilt of radius may limit ext
movements of wrist in frontal plane
50-60 total
ulnar dev = 0-35/40
radial dev = 0-15/20
ROM required for ADLs
40 deg flexion and extension in each direction
10 deg radial dev
30 deg ulnar dev
position of function of wrist
10-15 degree of ext
10 deg ulnar dev
what movements naturally occur with radial and ulnar dev
extension naturally occurs with radial dev
flexion naturally occurs with ulnar
arthrokinematics of wrist ext
convex lunate rolls dorsally (distal surface) and slides in a palmar direction
head of capitate rolls dorsally on lunate and slides in palmar direction
combination of both
closed packed position of wrist
full extension
arthrokinematics of wrist flexion
convex lunate rolls palmarly and slides dorsally
head of capitate rolls palmarly on lunate and slides in dorsal direction
arthrokinematics of ulnar deviation
metacarpal more than radiocarpal
RC: scaphoid, lunate, and triquetrum roll in ulnar direction and slide radially
radial deviation arthrokinematics
roll radially and slide ulnarly
carpals run into radius
80% mvmt at MC joint
what is carpal instability
excessive mobility between carpals
usually laxity/ruptured lig
can be static or dynamic
describe rotational collapse of the wrist
mechanically proximal carpals are a row of mobile bone between 2 relatively rigid segments
may collapse due to compression
lunate is most frequently dislocated carpal bone
radial n supplies what
all muscles that cross dorsal side of wrist
ECRB, ECRL, ECU
median and ulnar nn supply what
all muscles that cross the palmar side of the wrist
median = FCR, PL
ulnar = FCU
sensory innervations of wrist joint
RC and MC = C6 and C7
MC = C8
primary wrist extensors
act only on wrist
extensor carpi radialis longus and brevis
extensor carpi ulnaris
secondary wrist flexors
act on wrist and hand
extensor digitorum
extensor indicis
extensor digiti minimi
extensor pollicis longus
what structure secures extensor tendons into place
extensor retinaculum
prevents bowstringing up
how many fibro-osseus compartments are in the wrist/hand
6
can develop tenosynovitis
what compartment does de quervains tenosynovitis occur
in compartment I
pressing on power tools, gripping, or wringing out clothes
each muscles moment arm for a particular action is equal to what
perpendicular distance between the particular axis and the position of the muscles tendon
describe the muscle mechanics involved with producing a string grip
contraction of extrinsic finger flexors = flexion of fingers and creates wrist flexion torque
activation of wrist extensors = block wrist flexion caused by activated flexors
wrist extensors maintain optimal length of finger flexors to effectively flex fingers
when does maximal grip force occur
about 30 deg extension
sxs of lateral epicondylitis
painful/weak grip
pain with passive wrist flexion and pronation
tender over lateral epicondyle
can see degeneration/inflammation
what happens with lateral epicondylistis
light grasp ECRB
force increases with ECR and ECRL
primary wrist flexors
flexor carpi ulnaris and radialis
palmaris longus (absent in 15%)
palmar carpal ligament stabilizes/prevents bowstringing
secondary flexors of the wrist
flexor digitorum profundus and superficialis
flexor pollicis longus
abductor pollicis longus
extensor pollicis longus
what muscle provides the greatest wrist flexion torque of all 3 flexors
FCU
what muscles work together as synergists opposing deviations
FCU and FCR
force comparison between wrist flexors and extensors
wrist flexors are able to produce at 70% greater isometric torque than extensors
peak wrist flexion torque is when
at 40 deg flex
peak wrist ext torque is when
30-70 deg of ext
muscles that radially deviate
Extensor carpi radialis loggus and brevis
Extensor pollicis longus and brevis
abductor pollicis longus
flexor pollicis longus
radial deviators are greater than ulnar by 15%
muscles that ulnarly deviate
extensor carpi ulnaris
flexor carpi ulnaris
flexor digitorum profundus and superficialis
extensor digitorum
