Arm, elbow & forearm

Question 1

What are the three factors of the humerus alignment?

Answer 1

1. humeral torsion
2. anterior curve distal end
3. oblique inferomedial joint axis (causes valgus elbow alignment)

Question 2

what is the alignment of the elbow?

Answer 2

valgus (laterally deviated) 10-15 degrees

Question 3

what are the separate articulations within capsule of the elbow joint complex?

Answer 3

1. humeroulnar joint
2. humeroradial joint
3. proximal radioulnar joint

Question 4

what are the articulations of the humeroulnar joint?

Answer 4

trochlea of humerus and the trochlear notch of ulna

Question 5

what are the articulations of the radiohumeral joint?

Answer 5

capitulum of humerus and the head of the radius

Question 6

what is the difference between a primary and secondary constraint?

Answer 6

A primary constraint is defined as a constraint where release of that structure causes laxity of the joint. A secondary constraint is a constraint where release alone is insufficient to cause laxity, but where release after division of primary constraint increases the laxity of the joint.

Question 7

what are the primary constraints of elbow joint complex?

Answer 7

ulnohumeral articulation (valgus and varus) anterior medial collateral ligament (valgus) lateral collateral ligament complex (varus)

Question 8

what are the secondary constraints of the elbow joint complex?

Answer 8

radiohumeral articulation (valgus) common ext tendon (varus), capsule (valgus), common flex-pron tendon (valgus)

Question 9

what are the parts of the medial collateral ligament?

Answer 9

1. anterior band (AMCL) - well defined
2. posterior band (PMCL) - weaker
3. transverse band (TMCL) - no contribution to elbow joint stability

Question 10

what is the primary restraint to valgus force especially in flexion?

Answer 10

anterior medial collateral ligament

Question 11

what comprises the lateral collateral ligament complex?

Answer 11

1. lateral/radial collateral ligament (LCL or RCL)
2. annular ligament (AL)
3. lateral ulnar collateral ligament (LUCL)

Question 12

what is the primary varus constraint?

Answer 12

lateral collateral ligament complex

Question 13

which elbow flexors produce the most force (PCSA)?

Answer 13

1. brachialis
2. bicep brachial
3. pronator teres
4. brachioradialis

Question 14

which elbow flexors have the greatest moment arm?

Answer 14

1. brachioradialis
2. biceps brachii
3. brachialis
4. pronator teres

Question 15

what are the two primary elbow flexors?

Answer 15

biceps brachii and brachialis

Question 16

what are the three components of integrated forearm function?

Answer 16

1. proximal radioulnar joint and annular ligament
2. interosseous membrane/ligament
3. distal radioulnar joint and TFCC

Question 17

what are the articulations of the proximal radioulnar joint (PRUJ)?

Answer 17

head of the radius articulates with radial notch of ulna

Question 18

what type of joint is the proximal radioulnar joint and what is its primary and secondary stabilisers?

Answer 18

synovial pivot joint
primary stabiliser = annular ligament
secondary stabiliser = interosseous membrane

Question 19

what are the functions of the interosseous membrane and ligament?

Answer 19

1. attaché,ent site for muscles
2. hinge for forearm rotation
3. stabilise proximal and distal radioulnar joint
4. distribute load from radius to the ulna in the proximal forearm

Question 20

What are the articulations of the distal radioulnar joint (DRUJ)?

Answer 20

vertical part = distal ulna articulates with ulnar notch of radius
horizontal part = distal ulna articulates with triangular fibrocartilage disc

Question 21

what type of joint is distal radioulnar joint (DRUJ) and what are its primary stabilisers?

Answer 21

synovial plane joint
primary passive stabilisers = triangular fibrocartilage complex (TFCC) includes triangular fibrocartilage and dorsal & palmar radioulnar ligaments

Question 22

what are the supinator and pronator muscles?

Answer 22

supinators; biceps brachii & supinator
pronators: pronator teres & pronator quadratus
(brachioradialis is an accessory pronator from a supinated position to a neutral position)

Question 23

what are the superificial muscles of the forearm (anteromedial compartment)?

Answer 23

Pronator teres
FCR (flexor carpi radialis)
Palmaris longus
FCU (flexor carpi ulnaris)

Question 24

what are the cubical fossa margins?

Answer 24

line between later and medial epicondyles, bracioradialis, pronator teres