Shoulder Flashcards
What is normal retroversion angle of the humerus?
retroversion = angle of torsion, or degrees head is rotated back
- normal angle = 30 degrees
What athletes tend to have larger angles of torsion?
baseball players and volleyball players, giving them greater external rotation
Describe how the scapula and clavicle lie on the frontal plane.
- scapula lies 35 degrees anterior to frontal plane (angles forward)
- clavicle lies 20 degrees posterior to frontal plane (angles backward)
Your patient is having difficulty elevating their arm, and you believe it to be an SC joint issue. What exactly could be happening at the SC to prevent humeral elevation?
clavicle may not be sliding down while it’s rolling up, preventing the motion of arm elevation
T/F: With arm elevation, the clavicle protracts.
false: retracts
What arthrokinematic motions occur at the SC joint?
roll/slide (in opposite directions for elevation/depression)
roll/slide (in same directions for protraction/retraction)
spin (when post. rotation of clavicle occurs)
T/F: SC joint isn’t too important in ensuring full elevation.
false, need full motion of SC to get full elevation
Why are SC injuries so rare? When do they happen?
- due to strong ligaments protecting and good articulation
- could happen in traumatic injury: football, car accident, etc
What three ligaments keep the SC secure? What do they prevent?
1) sternoclavicular
- posterior portion: resists protraction
- anterior portion: resists elevation
2) interclavicular ligament: resists downward rotation
3) costoclavicular ligament: resists elevation and protraction
At what point does the clavicle posteriorly rotate?
after the costoclavicular ligament becomes taut, the clavicle rotates downward to keep elevating the arm
What’s the most important ligament in arm elevation?
costoclavicular ligament
What arthrokinematics occur during retraction for the SC?
transverse diameter, so concave on convex, so:
- posterior roll and slide
T/F: AC is convex acromion on concave clavicle.
- false, convex clavicle moves on concave acromion
T/F: Rolls and slides are in opposite directions for the AC.
true
Why might we be running into the acromion during elevation? (because of what specific accessory movement not happening)
- the scapula isn’t posteriorly tilting enough to bring the acromion back and out of the way
- this could be due to excessive anterior tilt; tight pec minor
How does the scapula sit at rest?
1) 35 degrees anterior to frontal plane (angled forward)
2) anteriorly tilted 10 degrees
3) slightly internally rotated
Anterior and posterior tilt of the scapula occur in what plane?
sagittal plane, about the frontal axis
Describe the scapulohumeral rhythm.
- scapula and humerus work together to allow extension at a 1:2 ratio, respectively
- first 30 degrees is from humerus, then scapula upwardly rotates 1 degree for every 2 from the humerus
• this ends with 60 degrees of rotation from scapula, and 120 degrees from the humerus
What motions occur at the AC during elevation? (think about what the clavicle is doing)
posterior roll, anterior slide (b/c clavicle retracts)
Upward and downward rotation of the scapula occur in what plane?
frontal plane along sagittal axis
What are 2 ligaments that become taught during elevation?
costoclavicular and coracoclavicular
What muscles elevate and depress the scapula?
1) elevate: levator scapulae, upper trap
2) depress: subclavius, lats, pec minor, lower trap
What muscles upwardly rotate and downwardly rotate the scapula?
- upward rotation: serratus anterior, upper and lower trap
- downward rotation: rhomboids, levator scapulae
What muscles protract and retract the scapula?
1) protract = serratus anterior, pec minor
2) retract = rhomboids, middle trap
With a weaker lower trap, what muscle is now utilized in elevation? How is this motion achieved, then?
upper trap used for elevation now
- since you’ve lost some upward rotation by losing some lower trap, you must rely on upper trap more, which means relying on elevation of scapula to get to full elevation vs upward rotation
What needs to happen at T-spine for full humoral elevation?
t-spine extension
What muscle opposes the serratus anterior during upward rotation of the scapula?
middle trap: serratus anterior pulls and abducts scapula for upward rotation, and middle trap pulls in and adducts, making sure not too much abduction occurs
Why is it more common to have anterior dislocation of the humerus?
b/c the labrumis thinner anteriorly and posteriorly, and the humerus already sits in a slightly anterior position
What 4 static stabilizers are there for the GH joint?
1) bony geometry
2) ligaments
3) labrum
4) capsule
What are the arthrokinematics for internal/external rotation at GH joint when it’s NOT at 90 degrees abduction?
GH internal rotation: roll anterior, slide posterior
GH external rotation: roll posterior, slide anterior
What does the coracohumeral ligament do?
resists adduction, inferior and anterior translation, external rotation
What GH ligaments prevent anterior and posterior translation of the humeral head?
SGHL and IGHL
What movements does the MGHL resist?
- anterior translation, esp. when arm is abducted to 45 degrees
- external rotation extremes
What does IGHL resist?
IGHL = 3 bands
- when abducted, resists extremes of ext/int rotation
- resists anterior and posterior translation
• esp. the anterior band
What is the rotator interval?
- space above subscap and below supraspinatus where no muscle overlap occurs
- more vulnerable area to dislocation (anteriorly)
At what degree of abduction of GH is there a spin at the joint when internal and external rotation occur?
90 degrees
If the scapula is fixed, how many degrees of humeral extension will you get?
120 degrees
Which manual muscle test would be stronger (thus producing more muscle torque), internal or external rotation for GH? Why?
internal is stronger because theres more CSA b/c more muscles do this motion than external
T/F: Internal rotation muscles control the velocity of external rotation muscles during pitching, spiking, etc.
true
What muscles begin abduction movement?
supraspinatus and middle delt
T/F: Deltoid can do internal and external rotation.
true; anterior does internal, posterior does external
Does spin occur in plain GH abduction/adduction?
no, just superior roll/inferior slide or inferior roll/superior slide
What acronym do we use to look for issues with the scapula?
- S - scapular malposition (too much tilt/wing/ downward)
- I - inferior medial border is prominent (winging)
- C - coracoid pain (or malpositioned)
- K - kinesia of scapula (correct movement)
What is open pack position for the GH?
70 degrees abduction, 30 degrees horiz adduction, neutral rotation
What is closed pack for the GH?
arm maximally abducted and externally rotated
What is loose pack for AC and SC?
arm at side
T/F: Closed pack for SC is when arm is maximally elevated.
true
What is closed pack for AC?
arm abducted 90 degrees
If you can guide your patient’s scapula through motion and your patient says that reduces pain, what should you work on strengthening?
scapular stabilizers like serratus anterior and rhomboids
If a Kibler scapular slide test is positive, what does that mean?
theres greater than 1.5cm difference between both sides, in movement or at rest (measured with tape measure)
What scapular movement do you need to get the last degrees of elevation?
external rotation
