Lecture 10: Joint Muscle Interaction Test 3 Flashcards
what parts of the brachial plexus supply the upper, middle, and lower trunks
upper = C5-6
middle = C7
lower = C7-T1
sensory innervation of the joints of the shoulder girdle
SC = C3-4 via cervial plexus
AC and GH = C5-6 via supra scapular and axillary nerves
nerves from the posterior cord of brachial plexus
axillary
sub scapular
thoracodorsal
nerves from the proximal segments of the brachial plexus
Dorsal Scapular
Long Thoracic
Pectoral
Suprascapular
muscles supplied by axillary N
deltoid
teres minor
muscles supplied by thoracodorsal N
Lats
muscles supplied by the upper sub scapular N
upper fibers of subscapularis
muscles supplied by lower sub scapular N
lower fibers of subscapularis
teres major
muscles supplied by lateral pectoral N
pectorals major
pectoralis minor (occasionally)
muscles supplied by medial pectoral N
pectorals major
pectoralis minor
muscles supplied by supra scapular N
supraspinatus
infraspinatus
muscles supplied by subclavian N
subclavius
muscles supplied by the dorsal scapular N
Rhomboids
levator scapula
muscles supplied by the long thoracic N
serratus anterior
what are proximal stabilizers
originate on spine/ribs/cranium and insert on scapula or clavicle
what are distal mobilizers
originate on scapula/clavicle and insert on humerus or forearm
ST elevator muscles
upper trap
levator scapulae
Rhomboids
retractors of the ST joint
middle trap
Rhomboids
lower trap
depressors of the ST joint
lower trap
lats
pec minor
subclavis
upward rotators of the ST joint
serratus anterior
upper and lower trap
protractors of the ST joint
serratus anterior
downward rotators of the ST joint
rhomboids
pec minor
generalized function of elevators of the ST joint
support posture of shoulder girdle and UE
if there is a problem with them, gravity determines resting position (usually protracted and excess downward RT of scapula)
generalized function of depressors of the ST joint if arm/scapula movement is blocked
can raise the thorax if arm is physically blocked or the scapula is stabilized/fixed
describe what happens with upper trap paralysis
occurs with polio
superior dislocation at SC
inferior sublux at GH joint (loss of upward fossa)
capsular ligaments are damaged
common with flaccid hemiplegia
generalized function/importance of the retractors of the ST joint
proximal stabilizations anchoring scapula to axial skeleton
essential for pulling activities
what muscles elevate the humerus at the GH joint
anterior (FLX/ABD) and middle deltoid (ABD)
supraspinatus (ABD)
coracobrachialis (FLX)
biceps brachii (FLX)
extreme upper fibers of infraspinatus and subscapularis slightly abd at GH
describe the compressive forces at the GH joint with ABD
large compression force 80-90% BW at 90 deg
130% BW with 2kg held at 90 deg
describe the dynamic stability of the shoulder with ABD
part of the SS tendon blends with superior capsule
active contraction pulls capsule tight to prevent it from being pinched between humerus and underside of acromion
at 90 deg ABD humeral head stretches the ICL (axillary pouch) which acts like a hammock supporting the head of the humerus
roles of the upward rotators of the ST joint
drive upward RT and furnish rotational adjustments of the scapula (posterior tilt and ER with full ABD)
provide stable attachments for the more distal mobilizers
what is scapular dyskinesia and what are the clinical manifestations
any abnormal position/movement of the scapula
manifestations
-reduced upward RT
-excessive downward RT, IR, anterior tilt, or elevation
what are the 3 categories of scapular dyskinesis
prominence of inferomedial border of scapula = type I
prominence of entire medial border of scapula = type II
prominence of superomedial border = type III
types I and II commonly associated with labral lesions; type III is associated with impingements and rotator cuff lesions
what do the rotator cuff muscles do at the GH joint during ABD
SS rolls the humeral head superiorly toward ABD while also compressing the joint for added stability
the rest of the muscles exert a downward force on the humeral head to counteract the excessive superior translation (especially that caused by deltoid contraction)
IS and teres minor can ER the humerus to increase clearance of greater tubercle and acromion
muscles that adduct and extend the shoulder
posterior deltoid
lats
teres minot
LH triceps
sternocostal head pec major
infraspinatus
teres minor
muscles that internally rotate the shoulder
subscapularis
pec major
lats
teres major
anterior deltoid
muscles that externally rotate the shoulder
infraspinatus
teres minor
posterior deltoid
