Ch 4 - MSK: Shoulder Flashcards
Describe normal ROM of the shoulder
• Flexion: 180° • Extension: 60° • Abduction: 180° – 120° w/ thumb down • Adduction: 60° • IR: 90° (w/ arm ABD) • ER: 90° (w/ arm ABD)
Describe muscles and innervation involved with shoulder flexion. (4 muscles)
- Anterior deltoid
- Pectoralis major, clavicular portion
- Biceps brachii
- Coracobrachialis
Describe muscles and innervation involved with shoulder extension. (5 muscles)
- Posterior deltoid
- Lat
- Teres major
- Triceps, long head
- Pec major, sternocostal portion
Describe muscles and innervation involved with shoulder ABDuction. (2 muscles)
- Middle deltoid
* Supraspinatus
Describe muscles and innervation involved with shoulder ADDuction. (7 muscles)
- Pec major
- Lat
- Teres major
- Coracobrachialis
- Infraspinatus
- Long head of triceps
- Anterior and posterior deltoid
Describe muscles and innervation involved with shoulder internal rotation. (5 muscles)
- Subscapularis
- Pec major
- Lat
- Anterior deltoid
- Teres major
Describe muscles and innervation involved with shoulder external rotation. (4 muscles)
- Infraspinatus
- Teres minor
- Deltoid, posterior portion
- Supraspinatus
How is arm abduction achieved?
Glenohumeral and scapulothoracic joint motion
There are _____ for every ____ during arm abduction
2 degrees glenohumeral motion for ever 1 degree of scapulothoracic motion
What does scapulothoracic motion allow?
Glenoid to rotate and permits glenohumeral abduction without acromial impingement
What % of the humeral head articulates with the glenoid fossa?
30%
What does the labrum prevent (shoulder)?
Anterior and posterior humeral head dislocation
What % does the labrum increase humeral contact with the glenoid?
70%
What is the purpose the superior glenohumeral ligament?
– Prevents inferior translation
– Provides stability from 0° to 90° of abduction with middle GHL
What is the purpose the middle glenohumeral ligament?
Prevents anterior shoulder translation
What is the purpose the inferior glenohumeral ligament?
Primary anterior ligament stabilizer above 90°
What are the dynamic stabilizers of the shoulder? (6 parts)
- Rotator cuff muscles
- Long head of the biceps tendon
- Deltoid
- Teres major
- Latissimus dorsi
- Scapular stabilizers
What are the static stabilizers of the shoulder? (4 parts)
Glenoid
Labrum
Capsule
Glenohumeral ligament
What are the ligaments of the AC joint? (3 ligaments)
AC ligament
Coracoclavicular ligament
Coracoacromial ligament
What does the AC ligament provide?
Horizontal stability
What does the CC ligament prevent?
Prevents vertical translation of the clavicle
Describe a type I AC separation.
Clavicle not elevated
AC lig: mild sprain
CC lig: intact
Describe a type II AC separation.
Clavicle not above the superior border of the acromion AC lig: ruptured CC lig: sprain Joint capsule: ruptured Deltoid: min detached Trapezius: min detached
Describe a type III AC separation.
Clavicle elevated above the superior border of the acromion but coracoclavicular distance is less than twice normal (i.e. <25 mm) AC lig: ruptured CC lig: ruptured joint capsule: ruptured deltoid: detached trapezius: detached
Describe a type IV AC separation.
Posterior and superior into the trapezius, giving a buttonhole appearance AC lig: ruptured CC lig: ruptured joint capsule: ruptured deltoid: detached trapezius: detached
Describe a type V AC separation.
Clavicle is markedly elevated and coracoclavicular distance is more than double normal (i.e. >25 mm) AC lig: ruptured CC lig: ruptured joint capsule: ruptured deltoid: detached trapezius: detached
Describe a type VI AC separation.
Clavicle inferiorly displaced behind coracobrachialis and biceps tendons, which is rare AC lig: ruptured CC lig: ruptured joint capsule: ruptured deltoid: detached trapezius: detached
Describe the Cross-chest (horizontal adduction or scarf) test.
Passive adduction of the arm across the midline causing joint tenderness
*AC Joint Impingement test
What type of x-rays should be done for AC separation?
Weighted anterior-posterior (AP) radiographs of the shoulders (10 lb)
What is seen on radiographs in a type III and V AC separation?
– Type III: 25% to 100% widening of the clavicular–coracoid area
– Type V: widening >100%
Describe treatment for a Type I and II AC separation.
– Rest, ice, NSAIDs
– Sling for comfort for the first 1 to 2 wks
– Avoid heavy lifting and contact sports
– Shoulder–girdle complex stabilization and strengthening
– RTP: asx w/ full ROM
Type I: 2 weeks
Type II: 6 weeks
Describe treatment for a Type III AC separation.
Surgical for those indicated (heavy laborers, athletes)
Describe treatment for a Type IV, V and VI AC separation.
ORIF or distal clavicular resection with reconstruction of the CC ligament
What are complications of AC joint injuries?
- Clavicular fxs and dislocations
- Distal clavicle osteolysis
- AC joint arthritis
What is Distal clavicle osteolysis?
Degeneration of the distal clavicle with associated osteopenia and cystic changes
What is GHJ instability?
Translation of the humeral head on the glenoid fossa
What is GHJ subluxation?
Incomplete separation of the humeral head from the glenoid fossa with immediate reduction
What is GHJ dislocation?
Complete separation of the humeral head from the glenoid fossa without immediate reduction
What is the most common direction of GHJ instability?
Anterior inferior
What is the mechanism of anterior GHJ instability? (arm motions)
Arm abduction and ER
Who most commonly has anterior GHJ instability?
Younger population and has a high recurrence rate
What are complications of anterior GHJ instability?
Axillary nerve injury
What is the mechanism of posterior GHJ instability?
Landing on a forward flexed ADDucted arm
Seizures
How does a patient with posterior GHJ instability present?
Arm ADDucted and IR position
What are traumatic patterns of GHJ instability?
"T.U.B.S." T - Traumatic shoulder instability U - Unidirectional B - Bankart lesion S - Surgical management
What are atraumatic patterns of GHJ instability?
"A.M.B.R.I." A - Atraumatic shoulder instability M - Multidirectional instability B - Bilateral lesions R - Rehabilitation management I - Inferior capsular shift, if surgery
Describe a Bankart lesion.
Labral tear of the anterior glenoid allows the humeral head to slip anteriorly and may be associated with avulsion fx of glenoid rim
What direction of GHJ dislocation are Bankart lesions associated with?
Anterior dislocations
Describe a Hill-Sachs lesion.
Compression fracture of the posterolateral humeral head caused by abutment against the anterior rim of the glenoid fossa
What direction of GHJ dislocation are Hill-Sachs lesions associated with?
Anterior dislocations
When can Hill-Sachs lesions cause instability?
> 30% of the articular surface may cause instability
What lesions are associated with posterior GHJ dislocations?
– Reverse Bankart lesion
– Reverse Hill–Sachs lesion
What are the symptoms of Dead arm syndrome?
Early shoulder fatigue, pain, numbness, and paresthesia
What causes Dead arm syndrome?
Shoulder slipping in and out of place MC when the arm is placed in the ABD and ER (“throwing position”)
Who most commonly gets Dead arm syndrome?
Athletes such as pitchers or volleyball players who require repetitive overhead arm motion
Describe the apprehension test (shoulder).
Feeling of anterior shoulder instability with 90° shoulder ABD and ER, causing apprehension
*Anterior glenohumeral instability
Describe the relocation test (shoulder).
Supine apprehension test with a posterior-directed force applied to the anterior aspect of the shoulder relieves the feeling of apprehension
*Anterior glenohumeral instability
Describe the anterior drawer test (shoulder).
Passive anterior displacement of the humeral head on the glenoid
*Anterior glenohumeral instability
Describe the anterior load-and-shift test (shoulder).
Humeral head is loaded against the glenoid and then passively displaced anteriorly
*Anterior glenohumeral instability/labrum instability