Muscle and Joint Interaction Flashcards
What innervates the entire UE?
Brachial plexus
What are the divisions of the brachial plexus?
Roots/Trunks/Subdivisions/Cords/Nerves
What innervates upper trunk, middle, and lower trunk?
C5-6 upper
c7 middle
C7- T1 lower
Where do the anterior and posterior divisions cross
around the clavicular level
What are the roots of the ventral rami of the brachial plexus?
C5-T1 roots
What is the sensory innervation of the SC joint?
C3-4 via cervical plexus
What is the sensory innervation of AC and GH joints?
C5-6 via suprascapular and axillary nerves
What are the nerves from the posterior cord of the brachial plexus?
Axillary
Subscapular
Thoracodorsal
What are the proximal segments of the brachial plexus?
Dorsal scapular
long thoracic
pectoral
suprascapular
What muscles are supplied by the axillary nerve?
Deltoid and teres minor
What muscles are supplied by the thoracodorsal nerve?
Latissimus dorsi
What muscles are supplied by the upper subscapular nerve?
Upper subscapularis
What muscles are supplied by the lower subscapular nerve?
Lower fibers of subscapularis and teres minor
What muscles are supplied by the lateral pectoral nerve?
Pectoralis major and occasionally the pec minor
What muscles are supplied by the medial pectoral nerve?
Pec major and pec minor
What muscles are supplied by the suprascapular nerve?
supraspinatus and infraspinatus
What muscles are supplied by the subclavian nerve?
Subclavius
What muscles are supplied by the long thoracic nerve?
Serratus anterior
What are the originations and insertions of proximal stabilizers of the shoulder muscles?
Originate on spine/ribs/cranium and insert on the scapula or clavicle
What are the originations and insertions of distal mobilizers of the shoulder muscles?
Originate on the scapula/clavicle and insert on the humerus or forearm
What does optimal function of the shoulder muscles require?
Coordinated interaction between proximal stabilizers and distal mobilizers
What muscles elevate the scapulothoracic joint?
Upper trap
levator scapulae
rhomboids
What muscles depress the scapulothoracic joint?
Lower trap
lat dorsi
pec minor
subclavius
What muscle protracts the scapulothoracic joint?
Serratus anterior
What muscles retract the scapulothoracic joint?
Middle trap
rhomboids
lower trap
What are the muscles that perform upwards rotation at the scapulothoracic joint?
Serratus anterior
upper and lower trap
What are the muscles that perform downward rotation at the scapulothoracic joint?
Rhomboids
pec minor
What is the innervation of the elevators of the shoulder?
Upper trap (CN X!)
Levator scapular ( dorsal scapular)
Rhomboids (dorsal scapular)
What will happen if there are issues with the elevator muscles of the ST?
Depressed and protracted and excessively downwardly rotated scapula
** can damage underlying structures over time
What innervates the depressors of the scapulothoracic ?
Lower trap (CNXI)
lat dorsi (thoracodorsal)
Pec minor (medial pectoral)
Subclavius (subclavian)
What can predispose someone to a subacromial impingement?
Scapula being inernally rotated and anteriorly tilted
What are the innervations of the protractors?
Serratus anterior (long thoracic)
pec minor (medial pectoral)
What is one way to work the protractors?
Push up plus
What is the innervations of the retractors?
Middle trap (CN XI)
rhomboids (dorsal scapular)
Lower trap (CN XI)
What do the retractors do? What are the retractors essential for?
Anchor scapula to axial skeleton
essential for pulling activities
What muscles elevate the humerus at the GH joint?
Anterior and middle deltoid
supraspinatus
coracobrachialis
biceps brachii
What does the anterior deltoid do? (Action of the shoulder)
Flexion and abduction
What does the middle deltoid do? (Action of the shoulder)
abduction
What does supraspinatus do? (Action of the shoulder)
abduction
What do the coracobrachialis and biceps brachii do? (Action of the shoulder)
Flexion
What compression forces do we have during abduction? (percentage of Body weight)
80-90% body weight at 90 degrees, 130% body weight holding 2kg at 90 degrees
What plane do the anterior deltoid, coracobrachialis, and long head of the biceps flex the GH joint in?
pure sagittal plane
What are the upward rotators of the ST joint?
Serratus anterior
upper and lower fibers of trapezius
What are the roles of the upward rotators of the ST joint?
Drive upward rotation and rotational adjustments of scapula
Provide stable attachments for more distal mobilizers
What force couple posteriorly tilts the scapula?
serratus anterior and lower trapezius
What force couple externally rotates the scapula?
Serratus anterior and middle trap
What happens with trapezius weakness while performing ST joint movements?
thoracic spine wont extend the normal 10-15 degrees
elevation can happen with excessive protraction
abduction very difficult
What are some consequences of the serratus anterior being weak?
scapula is abnormmally anteriorly tilted and internally rotated
scapula not properly stabilized against thorax; cannot resist pull of delt/SS ( -> causes downward roation of scapula and partial elevation of humerus )
What is scapular dyskinesis?
Any abnormal position or movement of the scapula
What are some common clinical manifestations of scapular dyskinesis?
- Reduced upward rotation
- excessive downward rotation, internal rotation, anterior tilt or elevation
What effect can scapular dyskinesis have on measurements at the shoulder?
Makes accurate and reliable measurements diffcult
What are the prominance of the inferomedial border of the scapula or the entire medial border of the scapula associated with?
Labral lesions
What is the prominence of the superomedial border of the scapula associated with?
impingement and rotator cuff lesions
What do the rotator cuff muscles do when activated?
form a protective cuff for the GH joint, actively rotate humeral head; compress & stabilize to centralize it in the fossa
What does dynamic stability require?
Healthy neuromuscular/ MSK systems
What integrates the neuromuscular and musculoskleletal systems?
proprioceptive sensory receptors within GH periarticular tissues
What does the supraspinatus do to the humeral head during abduction of the GH joint?
Supraspinatus rolls the humeral head superiorly while also compressing the joint for stability
What do Subscapularis, infraspinatus, and teres minor do during abduction of the GH joint?
exert a downward translational force on the humeral head to counteract excessive translation
** esp by the deltoid contracting
What do infraspinatus and teres minor do for the humerus during abduction?
Externally rotate humerus to increase clearance of greater tubercle and acromion
What muscles adduct and extend the shoulder?
Posterior deltoid
lat dorsi
teres major
long head of triceps brachii
Sternocostal head of pec major
** infraspinaus, teres minor assist
What does the humerus do to the pelvis when it is stable?
Brings pelvis upward
What stabilizes the scapula during adduction and extension of the shoulder?
Rhomboids
What muscles internally rotate the shoulder?
Subscapularis
pec major
lat dorsi
teres major
anterior deltoid
What muscles externally rotate the shoulder?
Infraspinatus
teres minor
posteror deltoid
When is the greatest moment of internal rotation? (degrees of elevation)
30 degrees of elevation
Does internal rotation or external rotation have greater mass/ torque?
Internal rotation 40-70% more torque
What can large internal torque throwing sports cause just before max external rotation?
Shear on the humerus
What does external rotation require from the humerus?
Must be stable
What has the lowest max effort torque of all shoulder but high velocity?
External rotation
Can muscles sustain more force eccentrically or concentrically?
eccentrically
