Shoulder Joint Flashcards
What are both the articulating surfaces of the glenohumeral joint covered in?
Hyaline cartilage
Where does the joint capsule of the shoulder extend to?
From the border of the glenoid fossa to the anatomical neck of the humerus
What kind of membrane lines the fibrous sheath of the joint capsule? What is the benefit of this?
Synovial membrane
Produces synovial fluid which reduced friction between articulating surfaces
How is friction reduced in the shoulder joint?
There are several synovial bursae
What is a synovial bursae?
Synovial fluid filled sac which acts as a cushion between tendons and other joint structures
Name the two clinically important bursae
Subacromial and subscapular
What does the subacromial bursae do?
Supports the deltoid and supraspinatus muscles
What does the subscapular bursae do?
Reduced wear and tear on subscapularis tendon during movement at the shoulder joint
Name the 3 ligaments of the shoulder joint
Glenohumeral ligaments (superior,middle, inferior)
Coracohumeral ligament
Transverse humeral ligament
Coracoacromial ligament
What are the attachments of the glenohumeral ligaments?
Run with the joint capsule from the joint capsule to the anatomical neck of the humerus
What is the action of the glenohumeral ligaments?
To stabilise the anterior aspect of the shoulder joint
What is the attachment of the coracohumeral ligament?
Attaches to the base of the coracoid process to the greater tubercle of the humerus
What is the action of the coracohumeral ligament?
Supports the superior part of the joint capsule
What are the attachments of the transverse humeral ligament?
Spans distance between the two tubercles of the humerus
What is the action of the transverse humeral ligament?
Hold the tendon of the long head of the bicep in the bicipital groove
What are the attachments of the coracoacromial ligament?
Runs between the acromion and the coracoid process of scapula (forms coraco-acromial arch)
What is the action of the coracoacromial ligament?
Prevents superior displacement of the humeral head
What is different about the coracoacromial ligament compared to the other 3 ligaments of the shoulder joint?
It is not a thickening of the joint capsule
What is the arterial blood supply to the shoulder joint?
Anterior and posterior circumflex humeral arteries
Suprascapular artery
What is the innervation of the shoulder joint?
Supplied by the axillary, suprascapular and lateral pectoral nerves (derived from roots C5 and C6)
What kind of injury would affect the innervation of the shoulder joint function?
An upper brachial plexus injury (Erb’s palsy)
What muscles permit extension at the shoulder?
Posterior deltoid, latissimus dorsi and teres major
What muscles permit flexion at the shoulder?
Bicep brachii, pectoralis major, anterior deltoid and coracobrachialis
What muscles permit adduction at the shoulder?
Pectoralis major, latissimus dorsi, teres major
What muscles permit abduction at the shoulder?
0-15 degrees- supraspinatus
15-90 degrees- middle deltoid fibres
90 + degrees - trapezoid and serratus anterior (rotate scapular)
What muscles permit medial rotation at the shoulder?
Subscapularis Pectoralis major Latissimus doris Teres major Anterior deltoid
What muscles permit lateral rotation at the shoulder?
Infraspinatus and teres minor
What are the factors contributing to the mobility of the shoulder joint?
- the fact that it is a ball and socket joint
- the disproportionate size of articulating surfaces
- laxity of joint capsule
What are the factors that contribute to the stability of the shoulder joint?
Rotator cuff muscles
Glenoid labrum
Ligaments
How are dislocation of the shoulder joint described?
By where the humeral head lies in relation to the infraglenoid tubercle
What is the more common type of shoulder dislocation?
Anterior dislocation
What is anterior dislocation usually caused by?
Excessive extension and lateral rotation of the humerus
Humeral head is forced anteriorly and inferiorly- into the weakest part of the joint capsule
Which two nerves can be effected by dislocations?
Axillary and radial
What does injury to the axillary nerve cause?
Paralysis of deltoid and loss of sensation over regimental badge area
What does rotator cuff tendinitis do to the shoulder joint over time?
Causes degenerative changes in the subacromial bursa and subsequently the supraspinatus tendon- increased friction between structures
What is a characteristic sign of rotator cuff tendonitis?
Painful arc pain in the middle of abduction (where affected area comes into contact with the acromion)
Posterior shoulder dislocations are less common and can easily be missed clinically and on x-ray. But how could these sort of breaks occur?
Electric shock, seizures
How would someone present clinically with a posterior shoulder dislocation?
They wouldn’t be able to externally rotate at the shoulder because it is fixed in internal rotation
How would you fix a clavicle fracture? What are the risks of this?
Wires and surgery
Wires may break and cause damage elsewhere
Name a common degenerative condition of the shoulder joint
Calcification tendonitis- calcium hydroxyapatite deposit- tendon turns to bone
What is popeye muscle? How is it treated
When the long head of the bicep ruptures and causes a bulging in the arm.
This is just cosmetic there is no need for surgery
How would someone with impingement of the shoulder joint present clinically?
Low painful arc (once arm is past 90 degrees its fine)
Tender over tuberosity
Hawkins test +ive
How would you treat someone with impingement of the shoulder joint?
Steroids and physio
Or surgical decompression
What complications may occur after anterior dislocation of the shoulder?
Damage to axillary nerve. Axillary nerve runs posteriorly to head of humerus so dislocation anteriorly will pull on the axillary nerve.
How would examine a patient who had dislocated their shoulder to determine the integrity of the axillary nerve?
What would you not do and why?
Test for sensation at regimental badge area (where injections happen)
Test for motor function in acute trauma
