1the elbow mainly has what roles
mobility
positions the hand in space
stability
acts as a stable platform for forceful tasks
2capitulum
articulating surface for the radius
3the trochlea is not horizontal which causes
some normal amount of valgus - carrying angle
4in extension, there is ___ space between the humerus and the radial head
more
5the fibrous joint capusle blends with what ligaments?
annular and collateral ligaments
6the ligaments are what anteriorly?
loose and reduntant
but can get stiff very quickly
7anterior band of the MCL restrains
valgus forces from 20-120 degrees of elbow flexion
8posterior band of MCL restrains
valgus forces at greater than 90 degrees elbow flexion
9lateral radial collateral ligament provides restraint to what 2 things?
varus forces
supination
10lateral ulnar collateral ligament does what?
works with extensor/supinator muscles to help provide dynamic support of the lateral elbow
11annular ligament
helps to stabilize radial head
12posterolateral rotary instability
combined supination, valgus, and axial load
13What does FOOSH disrupt?
the Lateral collateral ligament complex
Lateral ulnar and radial collateral
-Excessive supination with axial load
14arthrokinematics of proximal radioulnar joint?
convex radial head
concave notch of the ulna
15annular ligament function
holds radial head on the notch
16what is the annular ligament lined with
hyaline cartilage -> less friction so the head can spin
17arthrokinematics at distal radioulnar joint
concave ulnar notch of the radius
convex ulnar head
18TFCC
similar to meniscus
helps with load bearing forces
19distal radioulnar joint ligaments
dorsal and palmar radioulnar ligaments
20dorsal radioulnar ligament is tensioned in
pronation
21palmar radioulnar ligament is tensioned in
supination
22how is the palmar ligament related to the ulna?
pulla ulna towards the palm, in supination the styloid goes inside
23how does the radioulnar interossei contribute to joint stability?
the fibers are oriented superior and laterally (upward from ulna to the radius), so the forces are initially absorbed by the bigger radius and then transferred down to the larger ulna superiorly
-fiber orientation prevents the radius from translating up
24work horse of elbow flexion
brachialis
25what is useful about the brachialis?
large CSA and inserts close to the joint axis
-can produce force and ROM
force generation does NOT depend on the position of the forearm or shoulder
26the biceps brachii has the potential for
active insufficiency
27the biceps brachii is most active when there is little resistance to elbow
flexion with the forearm in supination or neutral
28the biceps brachii is active is all positions of the forearm when there
is resistance
29the brachioradialis only active with
fast or loaded movement when the forearm is in neutral or pronation
30function of brachioradialis
helps pronate in supination and supinate in pronation
31wrist flexors and wrist extensors are both weak
elbow flexors
32all heads of the triceps are active during
quick or resisted elbow extension
33pronator teres helps with
forceful pronation
weak elbow flexor
stabilie the PRUJ and HRJ
34which pronator does the body prefer?
pronator quadratus because it won't contribute to elbow flexion, otherwise would need an extensor to counteract
35pronator quadratus
involved in both fast/slow and resisted / unresisted pronation
excellent stabilizer of the DRUJ - compressive line of pull
36supinator
can function alone in unresisted, slow supination or in fast supination with the elbow extended
-not good with force production
37biceps brachii and supination
always involved in resisted supination
involved in fast unresisted supination when the elbow is in flexion
38forceful supination - synergist of biceps
biceps with LH of the Triceps so that there is no shoulder and elbow flexion
39pronation synergist
pronator teres and SH of triceps
40bicep curl synergist
biceps and post delt and lats (offset shoulder flexion)
41triceps dip synergist
triceps and ant delt and pec major
offset shoulder extension