Lecture 10: Joint Muscle Interaction Test 3

Question 1

what parts of the brachial plexus supply the upper, middle, and lower trunks

Answer 1

upper = C5-6

middle = C7

lower = C7-T1

Question 2

sensory innervation of the joints of the shoulder girdle

Answer 2

SC = C3-4 via cervial plexus

AC and GH = C5-6 via supra scapular and axillary nerves

Question 3

nerves from the posterior cord of brachial plexus

Answer 3

axillary
sub scapular
thoracodorsal

Question 4

nerves from the proximal segments of the brachial plexus

Answer 4

Dorsal Scapular
Long Thoracic
Pectoral
Suprascapular

Question 5

muscles supplied by axillary N

Answer 5

deltoid

teres minor

Question 6

muscles supplied by thoracodorsal N

Answer 6

Lats

Question 7

muscles supplied by the upper sub scapular N

Answer 7

upper fibers of subscapularis

Question 8

muscles supplied by lower sub scapular N

Answer 8

lower fibers of subscapularis

teres major

Question 9

muscles supplied by lateral pectoral N

Answer 9

pectorals major

pectoralis minor (occasionally)

Question 10

muscles supplied by medial pectoral N

Answer 10

pectorals major

pectoralis minor

Question 11

muscles supplied by supra scapular N

Answer 11

supraspinatus

infraspinatus

Question 12

muscles supplied by subclavian N

Answer 12

subclavius

Question 13

muscles supplied by the dorsal scapular N

Answer 13

Rhomboids

levator scapula

Question 14

muscles supplied by the long thoracic N

Answer 14

serratus anterior

Question 15

what are proximal stabilizers

Answer 15

originate on spine/ribs/cranium and insert on scapula or clavicle

Question 16

what are distal mobilizers

Answer 16

originate on scapula/clavicle and insert on humerus or forearm

Question 17

ST elevator muscles

Answer 17

upper trap
levator scapulae
Rhomboids

Question 18

retractors of the ST joint

Answer 18

middle trap
Rhomboids
lower trap

Question 19

depressors of the ST joint

Answer 19

lower trap
lats
pec minor
subclavis

Question 20

upward rotators of the ST joint

Answer 20

serratus anterior
upper and lower trap

Question 21

protractors of the ST joint

Answer 21

serratus anterior

Question 22

downward rotators of the ST joint

Answer 22

rhomboids
pec minor

Question 23

generalized function of elevators of the ST joint

Answer 23

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)

Question 24

generalized function of depressors of the ST joint if arm/scapula movement is blocked

Answer 24

can raise the thorax if arm is physically blocked or the scapula is stabilized/fixed

Question 25

describe what happens with upper trap paralysis

Answer 25

occurs with polio

superior dislocation at SC

inferior sublux at GH joint (loss of upward fossa)

capsular ligaments are damaged

common with flaccid hemiplegia

Question 26

generalized function/importance of the retractors of the ST joint

Answer 26

proximal stabilizations anchoring scapula to axial skeleton

essential for pulling activities

Question 27

what muscles elevate the humerus at the GH joint

Answer 27

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

Question 28

describe the compressive forces at the GH joint with ABD

Answer 28

large compression force 80-90% BW at 90 deg

130% BW with 2kg held at 90 deg

Question 29

describe the dynamic stability of the shoulder with ABD

Answer 29

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

Question 30

roles of the upward rotators of the ST joint

Answer 30

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

Question 31

what is scapular dyskinesia and what are the clinical manifestations

Answer 31

any abnormal position/movement of the scapula

manifestations
-reduced upward RT
-excessive downward RT, IR, anterior tilt, or elevation

Question 32

what are the 3 categories of scapular dyskinesis

Answer 32

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

Question 33

what do the rotator cuff muscles do at the GH joint during ABD

Answer 33

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

Question 34

muscles that adduct and extend the shoulder

Answer 34

posterior deltoid
lats
teres minot
LH triceps
sternocostal head pec major
infraspinatus
teres minor

Question 35

muscles that internally rotate the shoulder

Answer 35

subscapularis
pec major
lats
teres major
anterior deltoid

Question 36

muscles that externally rotate the shoulder

Answer 36

infraspinatus
teres minor
posterior deltoid