Scapula/shoulder Flashcards
Elevators of the scapula (4)
Upper trapezius
Levator scapulae
Rhomboid minor
Rhomboid major
Depressors of the scapula (6)
Levator scapula Rhomboid minor Rhomboid major?? Pectoralis minor Lower pectoralis major Latissimus dorsi
Upward rotators of the scapula (3)
Upper trapezius
Lower trapezius
Serratus anterior
Downward rotators of the scapula (7)
Anterior:
Lower pectoralis major
Pectoralis minor
Subclavius
Posterior: Latissimus dorsi Lower serratus anterior Lower trapezius Rhomboids
Shoulder facts
- Mobility at the expense of stability
- Shoulder girdle is composed of seven joints
- There are structures within the suprahumeral space
Clavicle facts
- clavical stability–> from ligaments
- clavical mobility–> from crank shape
Scapulohumeral rhythm
- scapular rotation
- glenohumeral movements
Shoulder girdle 7 joints
- glenohumeral
- scapulothoracic (or scapulocostal)
- suprahumeral* (pseudo-joint)
- acromioclavicular
- sternoclavicular
- costosternal
- costovertebral
Suprahumeral
*pseudo-joint
between head of humerus and arch formed by coracoacromial ligament (CA ligament)
Joint definition
union of two bones that permit movement at their junction
Suprahumeral “joint” function
- prevents upward dislocation of humerus
- protects glenohumeral joint from trauma above
Structures within the suprahumeral “joint”
- portion of subacromial bursa
- subcoracoid bursa
- supraspinatus muscle and tendon
- superior portion glenohumeral capsule
- portion of biceps tendon
- loose connective tissue
*vulnerable to compression by greater tuberosity during abduction (need to externally rotate)
Role of clavicle
- to keep the arm away from the body
- strong ligaments for stability
- “crank” shape of clavicle for mobility
Clavicular ligaments
- coracoclavicular ligment: trapezoid ligament & conoid ligament
- costroclavicular ligament: important fulcrum for shoulder girdle; between the clavicle and the underlying rib
- sternoclavicular ligament
Coracoacromial (CA) ligament
often cut out in athletes to give more room
AC joint separations (“shoulder separations”)
I- AC ligament partially torn
II- AC ligament completely torn
III- AC ligament and CC ligament completely torn
IV- type III with avulsion of CC ligament from clavicle
V- type III with vertical displacement of the clavicle and 100% increased of the coraco-clavicular space
VI- type III with inferior dislocation of distal clavicle
AC joint separations (“shoulder separations”) MCC?
Direct impact to the shoulder from a fall
Crank shape of the clavicle for mobility
Rotation of the clavicle begins after 90 degrees of abduction of the arm
- 60 degrees glenohumeral
- 30 degrees scapular rotation (2:1 ratio)
As scapula rotates next 30 degrees, the clavicle must rotate about its long axis.
In movements of the arm, sternoclavicular joint motion is a/w reciprocal motion in the AC joint.
TRUE
A congenital absence of the clavicle will result in little or no loss of functional ability in use of the shoulder.
TRUE
Glenohumeral abduction
supraspinatus
deltoid
*BOTH muscles are active throughout abduction
What happens when supraspinatus is paralyzed?
There is no difficulty raising arm above head, there is simply a decrease in strength and endurance.
What happens when deltoid is paralyzed?
- They attempt to raise arm by upward rotation of scapula and lateral bending of truck.
- Also frequently externally rotate so can use long head of biceps.
*Important: always check shoulder abduction with both internal and external rotation of shoulder!
Long head of biceps in external rotation
If the biceps long head is the muscle causing abduction (and thus, covering up loss of deltoid and supraspinatus), the patient will be able to abduct ONLY when in external rotation.
*All abduction will be lost when the shoulder is internally rotation!
Codman scapulohumeral movement
2:1 ratio
For every 15 degrees of abduction of the arm…
- 10 degrees occur at glenohumeral
- 5 degrees from rotation of scapula upon chest wall
Scapular rotation purpose
- mechanical stability of the glenohumeral joint
- to maintain optimal deltoid length (length-tension relationship)
Rotation of the scapula as in full abduction of the arm is produced by..?
trapezius and serratus anterior
Glenohumeral movement
- gliding of two incongruous surfaces
- large humeral head/small glenoid fossa
- glenoid fossa faces lateral/anterior/upward–> VERY important for this to be facing the correct way!
Glenoid capsule
- Arm at side hanging: superior capsule is taut, inferior is loose
- Arm in full abduction: superior capsule is loose, inferior is taut
- Arm half abducted: both superior and inferior capsule are slack so this is a position of instability
Scapula position affects inclined plane
-Ball compressed against inclined plane (glenoid fossa)
-Compressive forces created by:
superior capsular ligament
coracohumeral ligament
tendon of supraspinatus
Anterior capsule of the glenoid
- loose (humerus can be drawn 3 cm from fossa)
- reinforced by ligaments:
1. superior glenohumeral ligament
2. middle glenohumeral ligament
3. inferior glenohumeral ligament
*Between the superior and middle ligament is an opening called the Foramen of Weitbrecht
Foramen of Weitbrecht
When the humerus pops out, this is usually where is occurs.
*Between the superior and middle glenohumeral ligaments
Long head of the biceps brachii
- attaches to superior rim of the glenoid fossa
- invaginates glenohumeral capsule
- does not enter synovial cavity–> intracapsular but extrasynovial
Abduction range of the glenohumeral joint
- Active abduction to 90 degrees– an additional 30 degrees can be gained passively if the humerus rotates externally (external rotation allows the greater tuberosity to pass behind the acromion).
- With the arm internally rotated, the greater tuberosity impinges against the coracoacromial arch and blocks abduction at 60 degrees.
With the humerus internally rotated, the glenohumeral motion in abduction will be…
60 degrees
Arthrodesis of the Shoulder
- Takes away movement at the glenohumeral joint via fusion
- Recommendation: fixate in 20 degrees forward flexion, and 50 degrees abduction
What are two purposes of scapular rotation during arm abduction?
- keep the glenohumeral joint in the correct position
2. rotation of the scapula helps maintain optimal length/tension of the deltoid
Weakness of the deltoid (lateral part) is most easily demonstrated by testing abduction when the arm is…
In internal rotation
*When the arm is in external rotation, the long head of the biceps kicks in.
Glenohumeral joint fusion position of function?
- 20 degrees flexion
- 50 degrees abduction
The relationship of scapular to humeral motion is constant throughout the range of abduction.
TRUE
Abduction of the arm above the horizontal requires integrity of the trapezius.
FALSE- the trapezius is an upward rotator
In the normal individual in the anatomical position, a download subluxation at the glenohumeral joint is prevented by deltoid muscle tone.
FALSE- prevented by ligament and tendon (see compressive forces)
Rotation of the scapular as in full abduction of the arm is produced by the:
trapezius and serratus anterior
Rotator cuff muscles (SITS)
Supraspinatus
Infraspinatus
Teres minor (external rotation)
Subscapularis
Shoulder extension is performed by:
- posterior deltoid
- triceps, long head
- teres major
Teres major innervation
Lower subscapular nerve
The Putti-Platt operation is used for?
recurrent shoulder dislocation
Biceps Brachii Origin?
Short head- coracoid process
Logn head- superior rim of glenoid fossa
Biceps Brachii insertion?
Common tendon inserts on ulnar side of radius
Biceps Brachii action?
- Primary fx: supination
- Secondary fx: elbow flexion, shoulder flexion
*Can substitute for deltoid by external rotation of humerus so line of pull of biceps long head results in some abduction (example- polio pt)
Biceps mechanism
- passive
- bicipital groove moves under the biceps tendon which remains stationary
- overlying transverse humeral ligament
*Note: long head ligament gets worn out over time due to the groove moving under the biceps tendon–> elderly pts have the popeye biceps.
Supraspinatus
- MC rotator muscle to be torn
- fixes head of humerus to glenoid fossa
- active during entire abduction of arm (remember this!)
- paralysis will result only in slight decreased strength and endurance (still will be able to abduct full range)
What are the short rotators?
Infraspinatus, teres minor, subscapularis
*These muscles have a more downward pull so they tend to depress the head of the humerus in a downward rotatory direction
What takes place to abduct the arm?
Rotator Cuff
- rotate head of humerus into abduction
- glide humeral head downward
- fix head of humerus against glenoid fossa (especially supraspinatus)
- externally rotate humerus so greater tuberosity passes posterior to acromial process
Deltoid
-with above the deltoid angle of pull is such that it becomes a powerful abductor (instead of just vertical humeral pull)
Why does the hemiplegic shoulder sublux?
Theories:
- loss of “seating” function
- downward rotation of scapula
- functional scoliosis (so relative scapula depression)–> patient leans toward hemiside
- spasticity of latissimus dorsi
- weak serratus anterior
- secondary brachial plexus stretch injury
Pathomechanics of shoulder impingement syndrome
- repetitive overhead stress
- holding objects in front of body for long period
- round back posture increases proximity of acromion and greater tubercle
What makes the supraspinatus tendon vulnerable to rupture?
Relatively avascular critical zone in the tendon
Physical exam finding in impingement syndrome?
- Painful ARC of abduction
- When asked to abduct, patient will shrug to replace painful glenohumeral movement with excessive scapular movement
- point tenderness over
- point tenderness over acromion
Impingement Tests
- forcibly flex arm forward to extreme elevation (Neer’s)
- internally rotate arm and flex to 90 degrees (Hawkin’s)
*Positive test is pain
Hesitation test
pain at beginning and end of motion
Empty can test (another impingement test)
- Tests for supraspinatus impingement
- A positive test is pain and/or weakness
*Note: Pain alone is less accurate than actual weakness as pain can be the result of supraspinatus tendonitis.
Apley scratch test
- a method for assessing the ROM of the shoulders
- assesses external rotation and abduction
- reach behind head and place hand on tip of opposite shoulder–> pain
History of acute rotator cuff tear
- Acute event in someone with chronic shoulder symptoms (tendinitis)
- Acute event= direct fall upon extended arm, direct blow to forward flexed arm, attempt to lift heavy object outward
- Patient reports acute shoulder pain that progresses over the next few hours, felt snap in shoulder, and noted unable to abduct
Physical exam of patient with a COMPLETE rotator cuff tear?
- pt cannot actively abduct or externally rotate arm at all
- if arm is put in abducted position, can be weakly sustained by deltoid
Physical exam of patient with a INCOMPLETE rotator cuff tear?
-arm can be abducted but pain esp 45-90 degrees (same as tendonitis)
-strength of abduction is proportional to size of tear
-if increased pain on abduction…
when internally rotated- tear is in posterior superior position
when externally rotated- tear is in anterior position
-arm frequently “catches” at certain angle of abduction (both on way up and down)
Physical exam of patient with a COMPLETE OR INCOMPLETE rotator cuff tear?
- attempt to substitute for abduction with shoulder shrug
- drop arm test= minimal pressure on abducted arm causes it to drop (thus, also unable to lower arm slowly to side)
Complete rotator cuff tear
- Deltoid pulls shoulder vertical
- with external rotation, can get some abduction from the biceps
Suprascapular nerve entrapment anatomy
- C5/6 root
- upper trunk of brachial plexus
- muscles innervated: supraspinatus, infraspinatus
- carries sensation from posterior capsule of glenohumeral joint–> cause of posterior shoulder pain
- passes through suprascapular notch on superior border of scapular with overlying suprascapular ligament
Clinical features of suprascapular nerve entrapment
- presents as dull posterior shoulder pain; usually does not radiate down arm
- weakness of abduction (supraspinatus) and external rotation (infraspinatus)
- atrophy noted in infraspinatus; atrophy of both, but the trapezius covers the supraspinatus
- at rest arm assumes slight internal rotation
Functional limitations of of suprascapular nerve entrapment
- unable to scratch back of head
- unable to unlock the door with outstretched arm
- unable to write long series of words
- injury of suprascapular nerve is 10-15% impairment of shoulder
Etiology of suprascapular nerve entrapment
-Nerve compression from acute forceful or repetitive shoulder depression (i.e. gymnasts, football lineman)
Diagnosis of suprascapular nerve entrapment
-EMG
Treatment of suprascapular nerve entrapment
- avoid repetitive trauma from forceful or repetitive shoulder depression
- surgical release- resection of suprascapular ligament
Anatomy of quadrilateral space
Inferior- teres major
Superior- teres minor and subscapularis
Medial- long head of triceps
Lateral- surgical neck of humerus
What’s within the quadrilateral space?
- Axillary nerve
- Small veins
- Branches to triceps have already come off the radial nerve and lie close to axillary nerve at this point so the radial nerve is SPARED, but the TRICEPS branches may be involved
Clinical presentation of quadrilateral space syndrome?
-weakness of shoulder (axillary n.) and elbow (triceps)
Mechanism of injury of quadrilateral space syndrome?
- local trauma from falling backwards onto area or direct blow in that area
- frequently large hematoma develops in area but is kept localized
- extensive yet localized hematoma favors scar formation
Physical exam of quadrilateral space syndrome?
- deltoid paralysis obvious
- triceps weakness may be missed if not specifically checked
- rest of radial innervated muscles okay
- axillary sensory changes?
Surgical procedures for recurrent anterior shoulder dislocation?
Most common:
- bankart
- putt-platt
