Topic 3

Question 1

elbow joint

Answer 1

synovial, uniaxial, hinge
movements - flexion/extension in tranverse axis
articular surfaces - capitulum ofhumerusarticulates with capitulum of humerus and trochlea (proximal) notch of ulnar articles with trochlea of humerus.

Question 2

superior radioulnar joint

Answer 2

synovial, uniaxial, pivot
movements - pronation/supination in longitudinal axis
articular surfaces - head of radius and radial notch of ulnar.

elbow joint and superior RU joint make up elbow joint complex

articular capsule (shared) - attaches at articular margin of humerus, articular margin of ulnar, no direct attachment to radius, thickets and strongest at sides of joints, relatively weak anteriorly and posteriorly.

synovial membrane (shared) - common to both joints

extrasynovial fat pads - occupy fossae when the bony projections do not.

Question 3

ligaments of elbow joint complex

Answer 3

annular ligament - surrounds head of humerus, both attaches on ulnar, allows pronation/supination, funnel-shaped because it prevents inferior dislocation of radius but not cone-shaped in kids.

medial/ulnar collateral - prevents AB, anterior, posterior and transverse part.

lateral collateral - prevents AD

note - collateral ligaments are tense throughout flexion extension range.

Question 4

inferior RU joint

Answer 4

synovial, uniaxial, pivot
movements - pronation/supination in longitudinal axis.

articular surfaces - distal head of ulna and the ulnar notch of radius.

triangular fibrocartilage complex - load-bearing structure between the lunate, triquetrum, and ulnar head. The function of the TFCC is to act as a stabilizer for the ulnar aspect of the wrist.

Question 5

intermediate RU joint

Answer 5

fibrosis, syndesmosis
fibres pass downward from radius to ulnar - this allows force to travel up the radius and across to the ulnar, distributing the force (in order dissipate forces before it gets to sternoclavicular joint) force transfer

forces are transmitted from radius to ulnar, thence to humerus, shoulder girdle and thence axial skeleton.

interosseous membrane (and oblique cord) also acts as a fulcrum for pronation and supination, nerves and vessels lie on membrane, is also an attachment site for muscles.

Question 6

relationship between ulnar and radius

Answer 6

superior radioulnar joint - radial head spins on radial notch of ulnar.

at inferior radioulnar joint - 2 ways of doing pronation/supination
- pronation WITH translation - roll and slide of ulnar notch of radius on ulnar head.

• pronation WITHOUT translation - slight extension and abduction of ulnar - unlar basically gets out the way.

Question 7

mover and stabilizer muscle

Answer 7

mover - spurt - has a higher rotary component than transarticular component and proximal attachment is further away from fulcrum. - e.g. biceps.

stabilizer - shunt - has a higher transarticular component than rotary component, proximal attachment closer to fulcrum - e.g. brachioradialis.

Question 8

implications for recruitment of spurt and shunt muscles

Answer 8

where speed and load is decreased - use of a mover muscle

where speed and load is increased - use of mover muscle and recruit a stabiliser for joint stability.

Question 9

what are the rules for recruitment regarding spurt and shunt muscles

Answer 9

recruit a monokinetic muscle first - monokinetic means one movemnt, one joint.

recruit polynkinetic muscles as teh need for increased force increases.

recruit synergists as required.

recruit stabiliser muscles as load and or speed for increased stability.