Elbow, wrist & hand - final Flashcards
what does HU joint contribute to?
flex/ext
much of the stability
what does the HR jt contribute to?
flex/ext
ligaments support the radial head against the capitulum
what type of joint is HU?
modified hinge joint because ulna has a small amount of axial rotation
what axis is flex/ext of the elbow?
M-L
why does the ulna deviate laterally relative to humerus?
medial lip of trochlea is longer
what is carrying angle (cubitus valgus)? what’s the average carrying angle?
frontal plane angle
13 deg
true or false. carrying angle is greater on dominant side and greater with age
true
what is considered an excessive carrying angle?
20-25 deg
what 3 joints encompasses the capsule of elbow?
HR, HR, prox RU
what are the ligaments at the elbow? what are they good for?
MCL/UCL - medially
LCL/RCL - laterally
annular ligament - below LCL
good for multiplanar stability
what happens with a WB injury to MCL? what can it cause?
extended and valgus force
can cause compression fx, ulnar nerve injury, anterior capsule, medial musculature at epicondyle
what happens with a NWB injury to to MCL?
repetitive valgus producing strain, overhead athletes (esp baseball pitchers)
what is tommy john surgery?
repair of anterior fibers through a tendon graft from palmaris longus, gracilis or plantaris
how does the terrible triad injury happen? what is the terrible triad injury?
FOOSH and supinated
1. elbow joint dislocation
2. fx radial head
3. fx coronoid process
what problems can occur with a terrible triad injury even with surgery?
persistent instability
nerve damage
heterotopic ossification
stiffness
in full flexion of elbow, where does the coronoid process of ulna fit?
what axis is showing through center of trochlea?
coronoid fossa of humerus
M-L
HR joint rolls and slides in the _____ direction for flx/ext
same
HR joint provides _____ % lateral stability to ____ force
50
valgus
one joint capsule shares which joints?
RU, HU, HR
how is the radial head held with the ulna?
fibro-osseous ring
radial notch and annular ligament
what ligament has attachments of capsule, radial collateral and supinator?
annular ligament
where does the quadrate ligament run?
radial notch of ulna to radius
in the distal RU joint, the _____ ulna attaches into the _____ radius
convex
concave
what does the triangular fibrocartilage do?
holds head of ulna to radial notch during pronation/supination
what are the stabilizers of the distal RU joint?
triangular fibrocartilage complex
pronator quadratus
ECU tendon
distal oblique fibers of interosseous membrane
during supination, what rotates?
radius and carpal bones rotate around fixed humerus and distal ulna
during supination, what does the proximal radial head do?
rotates in fibro-osseous ring
does not slide/roll
during supination, what does the distal radius do?
rolls and slides in the same way around ulna head
during pronation, what rotates?
radius and carpal bones rotate around the fixed humerus and ulna
during pronation, what does the proximal surface of disc do?
slides across ulnar head
where is the axis of rotation during pronation/supination and what does it limit? what does it act like?
axis of rotation nearly parallel to interosseous membrane
limits tension
acts like isometric - stabilizer - constant level of stability
during pronation, what does distal radius do?
rolls and slides in the same way around ulna head
what joint is linked with any movement of elbow and forearm?
HR
what muscle pronates the forearm and pulls radius against capitulum (increases compression)?
pronator teres
when pulling something, what simultaneous motions occur? what muscles are fired?
90 deg elbow flx with 45 deg shoulder ext
biceps and post. delt fire
to push open a door, _____ extends and _____ flexes.
what muscle produces ext force? what muscle oppose & exceeds extensor torque?
elbow extends
shoulder flexes
triceps - extensor force
ant delt opposes extensor force
what two muscles supinate?
biceps
supinator
what is the relationship between elbow angle and force?
elbow flex at 30 degrees produces less force for the biceps to supinate vs elbow flex at 90
what is the relationship between elbow angle and force?
elbow flex at 30 degrees produces less force for the biceps to supinate vs elbow flex at 90
what muscle activates isometrically to neutralize strong elbow flx of biceps?
triceps
what’s happening in an open chain position to produce a pronation torque?
pronator rotates the radius relative to a fixed ulna
what’s happening in a closed chain position to produce a pronation torque?
infraspinatus rotates the humerus relative to a fixed scapula
pronator rotates the ulna relative to a fixed radius
what is the most frequently fractured carpal
scaphoid
what is the most unstable/most frequently dislocated carpal? why?
lunate
lack of strong ligs to capitate
no muscle attachment
what things work together to oppose deviation?
FCU and FCR
which has the strongest wrist flexion torque?
FCU
what is the position of comfort for elbow?
80 deg flx
open pack position
what carpal bones make up the proximal row? how are they joined?
scaphoid, lunate, triquetrum and pisiform
loosely joined
what carpal bones make up distal row? how are they joined?
trapezium, trapezoid, capitate, hamate
bound tightly by strong ligaments
arthrokinematics of Radiocarpal?
concave radius and disc
convex scaphoid and lunate
in what position is there the greatest contact at radiocarpal jt?
slight ext
ulnar dev
where is the midcarpal located?
between prox and distal rows
what space does the triangular fibrocartilage complex fill?
ulnocarpal space
how many degrees of freedom for the wrist?
2
flx-ext
ulnar-radial deviation
- also does wrist circumduction but not a DOF
where is the axis of the wrist?
what axis for flx/ext? ulnar/radial dev?
through head of capitate
M-L
A-P
what directs the osteokinematics of the entire hand?
rotation of the capitate
what is the position of function for ext and ulnar deviation?
10-15 ext
10 ulnar dev
what motions work together in the wrist?
flex - ulnar dev
ext - radial dev
what forms the central column of the wrist?
linkages between radius and lunate, medial compartment of midcarpal jt
describe the roll and slide of wrist ext (capitate and lunate)
convex on concave
rolls dorsally, slides palmar direction
what motion is closed pack position of wrist?
full extension
describe the roll and slide of wrist flx (capitate and lunate)
convex on concave
rolls palmar direction, slides dorsally
with ulnar deviation, RC rolls in ______ direction and slides in _______ direction
** same at MC jt
** reverse for radial dev
ulnar
radial
–opposites
what is carpal instability?
excessive motion between carpals usually due to laxity or rupture ligaments
when you make a fist, which groups of muscles contract? why is it important clinically?
flexors and extensors
when you address grip strength, you need to work on both flexors and extensors
when does max grip force occur?
30 deg ext
CMC thumb abduction arthrokinematics:
convex on concave
roll palmar slide dorsal
** reversed for adduction kinematics
which way does metacarpal move in flexion?
metacarpal rolls and slides in ulnar direction
which way does metacarpal move in extension?
metacarpal rolls and slides in lateral direction
what motions depend on opposition
pinching and gripping
opposition is combination of:
thumb MC abducts
flexion and medial rotation toward small finger, trapezium also spins slightly, small and ring finger cup to help
what position is full opposition?
closed pack
