Shoulder Anatomy Flashcards
SH Rhythm: Phase 1, part 1
0-30deg
GH contributes all motion, scapula does nothing
SH Rhythm: Phase 1, part 2
30-90deg
GH contributes 30
Scapula contributes 30
SH Rhythm: Phase 1, part 2 scapula motion is…
a) SC > AC
b) AC > SC
a) SC > AC
SH Rhythm: Phase 2 scapula motion is…
a) SC > AC
b) AC > SC
b) AC > SC
SH Rhythm: Phase 2
90-180deg
GH contributes 60
Scap contributes 30
SH Rhythm: overall, what is the ratio of GH:ST motion?
2:1
Phase 1: what scapula motions?
elevation
up rotation
post tipping
ER
At 90deg, why is GH ER important?
If no ER = jt would “lock” bc greater tub against acromial arch.
ER allows greater tub to clear arch.
Max elevation of GH frozen
60deg
Max elevation if no GH ER
90deg
CT contribution for unilateral elevation
last 10-20deg
contralat side bend
CT contribution for bilateral elevation
last 10-20deg
extension
Rhomboids action
Concentric: down rotates scap.
Eccentric: controls up rotation (generated by concentric action of Trap & Serratus Ant).
Upper trap is coupled with ____ Serratus Anterior
Lower
and vice versa
RC muscles are most active at _____deg elevation
0-115
painful arc SIS
60-120
painful arc AC
170-180
resting position of scapula
ribs 2-7
10-20deg ant tip
10-20deg up rotated
30-40deg IR
how is the resting position of the scapula affected with fwd head posture?
Scap down rotated
Slack on sup GH capsule
less flex ROM
RC musc contract to maintain jt integrity
causes of scap dyskinesis
musc weakness/imbalance
nerve, AC, or RC injury
sup labral tear
Anterior tip: what does it look like?
inf angle more prominent.
Anterior tip: weak muscles
lower trap
lats
serr ant
Anterior tip: tight muscles
pecs
Winging: what does it look like?
med border more prominent.
Winging: weak muscles
traps
rhomboids
serr ant
Winging: tight muscles
humeral rotators
Winging: other injuries that may cause it
SLAP
long thoracic nerve lesion
Elevated scapula: what does it look like?
sup angle elevated.
Elevated scapula: muscles involved
Overactive levator & upper trap.
Imbalanced up/low trap force couple.
Elevated scapula commonly seen w/ what conditions?
SIS
RC lesions
SC frontal plane motions
elevation (45)
depression (15)
SC frontal plane: what is convex/concave?
vex = clavicle cave = manubrium
SC transverse plane motions
protraction (15)
retraction (15)
SC transverse plane: what is convex/concave?
vex = manubrium cave = clavicle
SC sagittal plane motions
upward rotation (30-45)
AC ligaments
Coracoclavicular (Trapezoid & Conoid)
Acromioclavicular
Capsule
trapezoid lig checks what motion?
lateral movement of clavicle
conoid lig checks what motion?
superior movement of clavicle (upward rotation)
AC joint movements (and named for what?)
Ant/post tipping: direction of acromion
IR/ER: direction of glenoid
Up/down rotation: direction of glenoid
HH faces what directions in anatomic position?
medial
posterior
superior
Glenoid faces what directions in anatomic position?
lateral
anterior
superior
Orientation of glenoid/HH provides the most stability where?
posterior
inferior
GH joint capsule fiber pattern & purpose
Cross-liked pattern = tightens w/ ER/IR forces
GH Close-Pack position
full ABD
full ER
GH resting position
55 ABD
30 horiz ADD
GH lig: transverse humeral
holds BLH tdn in groove
GH lig: coracohumeral
stabilizes BLH tdn
provides inf stability from 0-50° ABD (w/ SGHL).
GH lig: coracoacromial
superior stability
SGHL stability
provides inferior stability
limits inferior translation of HH
0-50 ABD
MGHL stability
provides anterior stability
limits anterior translation of HH
45-60 ABD
limits ER (from 0-90 ABD)
IGHL anterior band
limits ant/inf translation at 90° ABD & ER
IGHL posterior band
limits post translation with ABD & IR
IGHL axillary pouch
like a hammock
supports HH in ABD.
ABD + ER = resists ant dislocation.
ABD + IR = resists post dislocation.
what is the rotator interval
Ant/sup space btwn subscap & supraspin tdns
contents of rotator interval
CHL
SGHL
BLH tdn
ant jt capsule
purpose of rotator interval
stability to GH & BLH tdn
limits excessive GH motion
contracture of rotator interval may lead to…
adhesive capsulitis
laxity of rotator interval may lead to…
GH instability
labrum purpose
deepens fossa by ~50%, increase surface area for HH.
Allows GH lig attachments to glenoid.
Limits HH translation.
labrum blood supply
only to periphery
cannot heal on its own without surgery
bursa purpose
alleviate friction by creating space btwn 2 tightly opposed structures
T/F: bursa cannot be strengthened/stretched
TRUE
non-contractile tissue