Glenohumeral Joint Flashcards
What type of Joint?
ball and socket,
Glenoid fossa
covers 1/4-1/3 of humeral head
Glenoid Labrum
deepens socket by 50%, enlarges socket contact by 75%, LH of biceps attachment
What gives it stability?
ligaments/capsule- pulls head into socket
muscles- RC provide dynamic stability
Intra-articular process- negative pressure slight function of capsule
osteology- scapula and glenoid fossa upwardly rotated(static stability)
Joint Capsule
loose capsule, reinforced by ligs and muscle
2x size of humerus
two openings- LH of biceps and sub scapular fossa
weak inferiorly
Ligaments of Joint
Coracohumeral, coracoacromial
Coracohumeral
base of coracoid process- anterior greater tubercle
limits ER, extreme flex and ext and inferior displacement
Coracoacromial
roof of GH joint, superior translation of humerus
Coracoacromial Arch
created by coracoarcomial ligament, accordion and coracoid process
1-2 cm superior to head
when arm ABD/ Flex space decreased by 1/2, smallest between 60-120 degrees scaption
Subacromial Space
supraspinatus, subacromial bursa, LH biceps tendon, superior joint capsule
Position of Greater tubercle
ER then ABD: Gr. Tub under acromion
IR then ABD- Gr. tub under arch
superior GH ligament
12-1 glenoid rim - anatomical neck near IT groove
most taut with ER at 0 degrees ABD
prevents inferior translation with arm at side
middle GH ligament
2-3 glenoid rim- anatomical neck medial to lesser tubercle
most taut at 45 degrees ABD
prevents anterior translation
Inferior GH joint: anterior band
3-4 glenoid rim- inferior lesser tubercle
prevents inferior translation at 90 degrees ABD and ER
Inferior GH joint: posterior band
7-9 glenoid rim - axillary pouch
prevents posterior inferior translation at ABD of 90 degrees and IR
