Shoulder Mechanics and Counterstrain Flashcards
What 4 joints make up the shoulder joint?
Scapulothoracic articulation
glenohumeral hoint
acromioclavicular joint
sternoclavicular joint
What are the 6 major motions of the shoulder joint?
Flexion Extension Abduction Adduction External rotation Internal rotation
What is the glenohumeral joint ‘designed’ for?
Maximum motion at the expense of decreased stability. Minimal osseous support.
Where do the first 30 degrees of shoulder abduction occur?
At the glenohumeral joint
What is scapulothoracic rhythm?
First 30 degrees of shoulder articulation occurs at the glenohumeral joint
After that, for every 2 degrees of motion at the the glenohumeral joint there is 1 degree of motion at scapulothoracic joint
Sometimes there’s a 3:2 ratio
What can happen if the scapulothoracic articulation is restricted? What dysfunctions are frequently associated with the scapulothoracic articulation?
Glenohumeral joint may have compensate with increased motion.
Frequently associated with thoracic spine and rib dysfunction
What 4 things can a restricted scapulothoracic joint predispose someone to?
A compensated glenohumeral joint (increased motion):
- instability
- impingement
- rotator cuff tendonitis
- tears
What does somatic dysfunction of the scapulothoracic articulation contribute to?
Imbalance in the muscles affecting scapular motion and scapular stability
What is another small joint that moves in response to scapular motion?
Sternoclavicular joint
What are the motions of the sternoclavicular joint?
Anteroposterior
Superoinferior
Rotational motion
How can the sternoclavicular joint become restricted from a distal structure?
Restriction from shoulder injury
Why is posterior dislocation of the sternoclavicular joint be bad?
Compromises important neurovascular structures
What is a frequent mode of injury for the acromioclavicular joint?
Becomes separated when someone lands or is hit on the point of the shoulder
How does the acromioclavicular joint become restricted?
Usually with shoulder injury
What are the motions of the acromioclavicular joint?
Anteroposterior
Superoinferior
Rotational motion
In a general sense, what innervates the upper extremities?
Brachial plexus
C5-T1
What is the course of the brachial plexus?
Between anterior and middle scalenes
Between the first rib and clavicle
Underneath the pectoralis minor muscle
What SDs can have a negative impact on the brachial plexus and upper extremity functions?
SDs affecting the: cervical spine upper thoracic spine upper ribs scalene muscles clavicle pectoralis minor
What innervates the glenohumeral muscles?
Brachial plexus
C5-T1
What are the primary flexors of the glenohumeral joint?
Pectoralis major
Anterior deltoid
coracobrachialis
What are the primary extensors of the glenohumeral joint?
Latissimus dorsi
Teres major
Posterior deltoid
Long head of triceps brachii
What are the primary abductors of the glenohumeral joint?
Deltoids
Supraspinatus
What are the primary adductors of the glenohumeral joint?
Pectoralis major
Latissimus dorsi
Teres major
Long head of triceps brachii
What are the primary external rotators of the glenohumeral joint?
Infraspinatus
Teres minor
Deltoid muscle
What are the primary internal rotators of the glenohumeral joint?
Subscapularis Pectoralis major Latissimus dorsi Deltoids Teres major
What is the innervation of pectoralis major?
C5-T1
What is the innervation of the deltoids?
Axillary nerve
C5 and C6
What is the innervation of coracobrachialis?
Musculocutaneous nerve
C5, C6, C7
What is the innervation for latissimus dorsi?
Thoracodorsal nerve
C6, C7, C8
What is the innervation for teres major?
Lower subscapular nerve
C5 and C6
What is the innervation for triceps brachii?
Radial nerve
C6 C7 C8
What is the innervation for supraspinatus?
Suprascapular nerve
C4, C5, C6
What is the innervation for infraspinatus?
Suprascapular nerve
C5, C6
What is the innervation for teres minor?
Axillary nerve
C5 and C6
What is the innervation for subscapularis?
Upper and lower subscapular nerves
C5, C6, C7
How can SD affect the function of muscles?
Can affect their nerve roots, and all mm ‘downstream’ of that nerve root will be affected
- often produces weakness
What are the 4 rotator cuff muscles?
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
What do the rotator cuff muscles do?
Work together to keep the head of the humerus centered in the glenoid fossa
Analogous to a seal balancing a ball on its nose
What happens if a rotator cuff muscle is out of balance?
Glenohumeral joint is less stable and more prone to injury
Can also happen if scapulothoracic rhythm is off
What is the arterial supply for the upper extremities?
Left and right subclavian arteries
What is the course for the arterial supply for the upper extremities?
Subclavian arteries pass over the top of the first rib between the anterior and middle scalene mm
What can affect upper extremity arterial supply?
SD of: anterior and middle scalenes upper thoracic vertebrae cervical vertebrae upper ribs clavicles fascia of the neck fascia of upper extremity
What is the venous drainage of the upper extremities? What is their passage?
Subclavian and brachiocephalic veins
Pass anterior to scalenes
How does SD affect the veins of the upper extremity?
SD along the course can lead to swelling and congestion due to poor drainage.
Swelling affects proprioception and slows down rehab
What is the lymphatic drainage of the upper extremities?
Through the thoracic inlet, ultimately
What SD affects lymph drainage of the upper extremities?
SD affecting thoracic inlet
- produces a mechanical restriction to lymph flow
- produces congestion in upper extremities
- reduces healing
- negatively affects rehabilitation
Where are the preganglionic sympathetic cell bodies for the upper extremities?
In T2-T6, in upper thoracic spinal segments
What happens to the smooth muscles when they receive sym inn?
Smooth mm in lymph vessels contract
- impedes lymph return,, reduced lumen size
- causes congestion
How does upper thoracic SD affect the upper extremities?
Increases sym tone
Decreased lymph drainage
- can lead to increased swelling
- impairs function and recovery
Where is force transmitted during throwing?
Force is transmitted from the ground
- through the lower extremity
- through spine
- through shoulder
- through entire upper extremity
Requires integration of all of these structures, if 1 breaks then all are at risk, esp the shoulder.
During overhand throw, what percentage of kinetic energy is generated by legs and trunk?
50% - half from ground, half from shoulder
What is needed for optimal rotator cuff function?
Stable scapula
What is scapular retraction during throwing stimulated by?
Ipsilateral hip and trunk extension
What does ipsilateral mean?
Same side
What else is necessary for throwing?
Engagement of the gluteal mm to stabilize pelvis
- contributes to scapular stabilization and control
What stabilizes the scapula during throwing?
Engagement of the gluteal mm to stabilize pelvis
- contributes to scapular stabilization and control
Lower trapezius
lower rhomboids
serratus anterior
What can destabilize the scapula during throwing?
Weak gluteals
Altered mm firing patterns - from SD
Psoas major mm tension
- alters hip extension
- freq involved with shoulder/rotator cuff injury
What is the braking mechanism of throwing?
MM fire to stop the large angular velocity that throwing creates at the glenohumeral joint
What mm are responsible for the braking mechanism of the shoulder, i.e. for throwing?
Posterior shoulder mm
- posterior deltoid
- teres minor
What are some common areas of dysfunction associated with the shoulder?
Sacrum innominates lumbar spine latissimus dorsi - tightness reduces shoulder flexion thoracolumbar region
Where do you find SD in the thoracolumbar region?
T10-T12
What is SD of the thoracolumbar region associated with?
Altered function of the thoracolumbar fascia
latissimus dorsi mm
psoas major mm
diaphragm
What is a reflex pattern you see with shoulder dysfunction?
Reflex pattern involving the adrenal glands
- somatovisceral or viscerosomatic, T6-L2
- assoc. with adrenal fatigue in overtrained athletes
What changes happen with bad posture?
Increased kyphosis - sitting slumped forward
- protracts the scapula
- Pec minor and biceps mm tighten
- hamstrings and psoas major mm tighten
Alters scapular function and position
What is the net result of bad posture?
Rotator cuff imbalance
- greater predisposition to injury
- superior migration of humeral head = impingement on rotator cuff
How do you treat shoulder problems?
Combine OMM with ROM and strengthening exercises
- treat whole patient, look out for systemic disease
What is procedure for counterstrain?
- Locate a tender point
- Establish a pain scale
- Find a position that reduces the discomfort to 3/10 at least
- Hold position for at least 90 seconds
- Slowly return patient to starting position
- Reasses
What if the patient fails to respond to conservative treatment or has progressive neurological symptoms?
Consider referral for further evaluation, maybe surgery.
