biomechanics elbow, forearm, wrist

Question 1

Flexion/extension, shorten/lengthen, upper extremity

Answer 1

humero ulnar joint
humero radial joint

Question 2

rotation- pronate/supination

Answer 2

proximal radioulnar joint
distal radioulnar joint

Question 3

functional range of motion of the elbow

Answer 3

30 to 130°

Question 4

capsular pattern for the elbow

Answer 4

Flexion greater than extension

Question 5

bony stability of the humeroulnar joint

Answer 5

interlocking of trochlea groove of humorous into ulnar trochlear

coronoid process into coronoid fossa
olecranon into olecranon fossa

Question 6

Coronoid process prevents

Answer 6

Posterior displacement with flexion

Question 7

olecranon prevents

Answer 7

Hyper extension

Question 8

elbow capsule

Answer 8

humeral ulnar, humero radial, proximal radioulnar joints

anterior and posterior are weak

Laterally reinforced with ligaments

Max volume is 70 to 80° of flexion

Question 9

Medial collateral ligament

Answer 9

anterior- 1° of valgus restraint through all elbow motion

Posterior - taught in full flexion

Transverse -no role in stability

Question 10

Lateral collateral ligament complex

Answer 10

lateral collateral ligament

Lateral ulnar collateral ligament

Annular ligament

Question 11

lateral (radial) collateral ligament

Answer 11

Fan shaped
lateral epicondyle to annular ligament

primary restraint to varus/ supination

Question 12

lateral ulnar collateral ligament

Answer 12

lateral epicondyle to supinator crest, ulna, and annular ligament

tight extreme flexion and any varus

secondary restraint to varus/supination

Question 13

annular ligament

Answer 13

Restraint- traction, lateral subluxation

Secondary restraint to varus/supination

Question 14

Axis of motion for the elbow

Answer 14

movement is through center of trochlea and capitulum

medial trochlea More distal

Carrying angle is about 13°

mediately deviate with flexion
Laterally deviate with extension

Increased angle may impact ulnar nerve

Question 15

Limits to elbow extension

Answer 15

anterior capsule
Flexor muscles
Bony olecranon process

Question 16

limits to elbow flexion

Answer 16

soft tissue
Posterior capsule
Extensor muscles
Bony- Radial head and coronoid process

Function limited with forearm in mid to full pronation

Question 17

humero ulnar joint positions

Answer 17

closed- full extension and supination
Open - 70° flexion and 10° supination

Question 18

humeroradial joint positions

Answer 18

closed- 90 degrees flexion 5° supination
Open -full extension and supination

Question 19

closed and open pack positions during elbow injury

Answer 19

Closed packed joints often fracture associated bones

Open packed joints often dislocate

Question 20

monteggia fx

Answer 20

fx proximal ulna
radial head dislocation

Question 21

role of interosseous membrane

Answer 21

binds radius to ulna
muscle attachments
Transfers force from radius to ulna

Question 22

Wight bearing from hand to forearm is through

Answer 22

the radius

The interosseous membrane distributes portion load to ulna

Question 23

Axis of motion for proximal and distal radio ulnar joints

Answer 23

Radial head through ulnar head

Question 24

proximal radial ulnar joint

Answer 24

within capsule with HU and HR joints

Annular ligament

Question 25

Annular ligament

Answer 25

allows spin Binds radius to ulna Prevents radial head displacement

Question 26

distal radioulnar joint

Answer 26

palmar RU lig dorsal RU lig articular disc

Question 27

palmar RU lig

Answer 27

tight in supination

Question 28

dorsal RU lig

Answer 28

tight in pronation

Question 29

articular disc (TFCC)

Answer 29

binds to distal radius ulna dual articular surface separates RU and RC joints central portion avascular

Question 30

RU joint arthro

Answer 30

pivot one dof rom-150 pronation- 75 supination-85 functional- 50 each capsular pattern- pro> sup

Question 31

pronation at RU jt

Answer 31

radial head spins in annular lig/radial notch radius rotates over ulna

Question 32

supination at RU

Answer 32

radial head spins in annular ligament radial notch radius unwinds from ulna

Question 33

treatment considerations for PRU and DRU

Answer 33

PRU- roll glide opposite (it only spins) DRU- roll glide same

Question 34

limits to supination

Answer 34

pronator teres pronator quadratus TFCC palmar DRUJ IOM

Question 35

limits to pronation

Answer 35

supinator biceps TFCC dorsal DRUL lig

Question 36

brachialis

Answer 36

prime mover- inserts close to joint of action unaffected by forearm position due to insertion on ulna

Question 37

biceps brachii

Answer 37

prime mover most effective 80-100 elbow flexion and with shoulder in extension good supinator at 90 flexion

Question 38

brachioradialis

Answer 38

stability muscle - inserts far from joint of action strongest at 90-120 elbow flexion with forearm in mid position

Question 39

pronator teres

Answer 39

small role in elbow flexion

Question 40

triceps

Answer 40

not influences by forearm position due to ulnar insertion max torque 90 flexion primarily medial head lateral and long head active with higher resistance or speed of contraction

Question 41

anconeus

Answer 41

helps initiate elbow extension may stabilize against varus force

Question 42

supinator

Answer 42

supinator functions regardless of elbow position

Question 43

biceps brachii- supination

Answer 43

used with higher force activity and when combined with flexion good supinator at 90 flexion

Question 44

radial wrist extensors

Answer 44

supination

Question 45

brachioradialis

Answer 45

can derotate forearm to neutral

Question 46

forearm pronators

Answer 46

pronator teres pronator quadratus flexor carpi radialis palmaris longus brachioradialis