GH Joint Flashcards
osteology
glenoid fossa + head of humerus
joint type
synovial; ball and socket
angle of inclination
130-150 degrees in frontal plane
retroversion
posterior orientation of humeral head with regard to the condyles
angle of torsion
- 30 degrees posterior in transverse plane
- also described as “30 degrees of retroversion”
increased humeral retroversion (greater than 30 degrees) may result in increased ____ ROM and reduced ____ ROM
- ER
- IR
the glenoid labrum enhances ____ and increases ____
- concavity
- articular surface
3 main functions of the glenoid labrum
- resists humeral head translations
- dissipates forces
- protects bony edges
the glenoid labrum is an attachment for what structures?
- GH ligaments
- tendon of biceps long head
what are the primary characteristics of the GH joint capsule?
- significant laxity, minimal stability
- potential vol. size is 2x the size of the humeral head
- reinforced by thicker external ligaments
- inferior portion is slack in ADducted position, creating axillary pouch
tightness in the posterior shoulder capsule may produce increased ____ which decreases the ____ space
- anterior humeral head translation
- subacromial space
superior GH ligament
- limits ER and anterior/inferior translation at 0 degrees of ABD
- slackens when ABducted beyond 35-45 degrees
middle GH ligament
-limits anterior translation from 45-90 degrees of ABD and extremes of ER
inferior GH ligament
- anterior band, posterior band, axillary pouch
- primary stabilizer beyond 45 degrees of ABD or with combined ABD and rotation
during ABD, what does the axillary pouch of the inferior GH ligament resist?
inferior and anterior/posterior translation
during ABD and lateral rotation, what does the anterior band of the inferior GH ligament resist?
- anterior translation
- also resists anterior translation in neutral position
during ABD and medial rotation, what does the posterior band of the inferior GH ligament resist?
posterior translation
coracohumeral ligament
limits inf translation and ER of humeral head with arm in dependent position
rotator cuff
- reinforces GH joint capsule
- protects and actively stabilizes GH joint with dynamic activities
2 areas where rotator cuff does not reinforce
- inferiorly
- region btw subscap and supraspinatus (rotator interval)
what reinforces the rotator interval?
- biceps long head
- coracohumeral ligament
- sup/middle GH ligaments
osteokinematics of the GH joint
- flexion/extension
- ABD/ADD
- ER/IR
arthrokinematics of the GH joint
- spin
- sup/inf glide
- ant/post glide
GH joint flexion AK
- superior roll, inferior glide (opposite bc convex humerus is moving on concave glenoid)
- causes tension throughout the capsule
slight ____ translation may occur at end range flexion due to ____ in posterior capsule
- anterior
- tension
GH joint extension AK
inferior roll, superior glide
GH joint ADD AK
inferior roll, superior glide
GH joint ABD AK
superior roll, inferior glide
ABD is usually accompanied by ____
ER
what does supraspinatus contraction do to the superior capsule?
tightens it
what happens to inferior GH ligament during ABD?
tightens
GH joint ER AK
posterior roll, anterior glide
GH joint IR AK
anterior roll, posterior glide
GH closed packed position
90 degrees ABD and full ER, or full ABD and ER
GH capsular pattern
ER > ABD > IR
