Elbow, forearm, wrist Flashcards
Elbow complex
anatomically two articulations
Humeroulnar joint is what type?
simple hinge
Humeroradial joint is what type?
pivot joint resembling very shallow ball and socket; radius is the socket
Humoral ulnar joint movement
-single degree of freedom in sagittal plane
-0-140 degrees flex/ext
Forearm motion
-1 degree of freedom
-transverse plane
-involves 3 joints (humeroradial spins, proximal and distal radio-ulnar glide)
Which humeral condyle is longer? What does it create?
medial; carrying angle (normal 5-15 degrees)
Collateral ligaments: medial vs. lateral
-medial collateral sprains more common than lateral w/ fall onto outstx hand
Annular ligament
constrains radial head while allowing spin (band that secures radial head onto ulna)
What is a universal concern after elbow trauma/immobilization?
stiffness
Compensatory motion for pronation
shoulder abd and IR
Compensatory motion for supination
none
What to anticipate w/ epicondylar fracture?
flex/ext contractures
What to anticipate w/ radial head fracture?
pro/sup hurdles
Casting after elbow trauma should bias towards…
flex and sup
What insufficiency occurs w/ passive wrist extension
-fist = more extension
-fingers extended = less (flexors are passively insufficient b/c lengthened)
Muscles of elbow
-brachialis: inserts into ulna, originates on humerus (pure flexor)
-biceps: inserts into radius; flexor and supinator
-brachioradialis: inserts into distal radius; type III lever w/ elbow in mid range flex
-triceps: extensors
Medial mass forearm muscles
pronators, wrist and finger flexors
Lateral mass forearm muscles
supinators, wrist and finger extensors
Major proximal artery/vein in shoulder complex
axillary
Two major mixed nerves proximally
axillary, musculocutaneous
3 major nerves distally at elbow (2 ant. and 1 post. to joint axis)
-anterior: radial, median
-posterior: ulnar
Where can nerve entrapments occur? What damage can they cause?
-ulnar in cubital tunnel (damage causes claw hand)
-median travels in carpal tunnel, entrapment ant. forearm (damage thumb muscles)
-radial entrapment in fascia(?) damage causes wrist drop
Mobility/stability in RA? What deviation?
more mobility, less stability into ulnar deviation
Thrower’s elbow
repetitive valgus stress on medial collateral ligament
Little League elbow
stress on cartilage growth plate
Nursemaid’s elbow
dislocate radial head out of annular ligament
Active insufficiency
muscles too shortened and no longer has ability to generate effective muscular force
Passive insufficiency
muscles too lengthened and no longer has ability to generate optimal muscular force
Radial nerve palsy does what to long finger flexors?
active insufficiency
Hand rules of 1/2’s
thumb is 1/2 and sensation is 1/2 hand function
Digit alignment
each finger naturally flexes to center of wrist (lunate; combined flexion is system of stability)
Degrees of freedom in MP joint
2; flex/ext, abd/add
Degrees of freedom in DIP joint
1; flex/ext
Degrees of freedom in C-MC joint
3; flex/ext, abd/add, opposition
Ligaments of hand
-collateral ligaments at all articulations
-transverse ligaments across heads of finger metacarpals
Collateral ligaments in flexion and extension
-flexion = closed pack
-extension = loose pack
Carpal-metacarpal joint arthrokinematics
-flex/ext: distal concave moving on proximal convex (trapezium convex)
-abd/add: distal convex moving on proximal concave (trapezium concave)
think saddle
What is the resting hand position?
30 degree wrist ext, 80 degrees MP flex, full IP ext
What are the extrinsic finger muscles?
MP extensors, long finger flexors
What are the intrinsic finger muscles?
lumbricals, interossei
What are the extrinsic thumb muscles?
FPL, APL, EPL and EPB
What are the intrinsic thumb muscles?
thenar eminence (FPL, APB, OP)
Grips for power and what muscles
power and hook; extrinsic muscles, long finger flexors
Grips for precision and what muscles
pinch/precision grip; intrinsic muscles and thumb
