Shoulder Joint Flashcards
What reduces the disproportion between the head of humerus and the glenoid fossa?
Fossa is deepened by a fibrocartilage rim - the glenoid labrum
What is the glenohumeral joint formed by?
Head of humerus with glenoid cavity of scapula
What is a bursa?
A fluid filled sac which acts as a cushion between tendons and other joint structures
Name two clinically important bursa in the joint and where they are located
Subacromial - inferior to deltoid and acromion, superior to supraspinatus tendon and joint capsule.
Subscapular - between subscapularis tendon and the scapula.
Name three ligaments of the joint and the aspect that they stabilise
Glenohumeral - anterior
Coracohumeral - supports the superior part
Transverse humeral - holds the tendon of the long head of the biceps in the intertubercular groove
What forms the coraco-acromion arch? What is its function?
Coracoacromion ligament
Prevents superior displacement of the humeral head
Which arteries supply the glenohumeral joint?
The posterior and anterior circumflex humeral arteries
Which nerves supply the joint?
Axillary, suprascapular and lateral pectoral nerves
What are all the movements of the glenohumeral joint?
Extension and flexion
Abduction and adduction
Medial and lateral rotation
What muscles extend the shoulder?
Posterior deltoid
Latissiumus dorsi
Teres major
Which muscles perform flexion?
Biceps brachii
Pec major
Anterior deltoid
Coracobrachialis
Abduction?
0-15: supraspinatus
15-90: middle deltoid
90*+: trapezius and serratus anterior
What muscles do adduction?
Pec major, latissiumus dorsi and teres major
Muscles for medial rotation?
Subscapularis, pec major, latissimus dorsi, teres major
Lateral rotation
Infraspinatus, teres minor
Name the rotator cuff muscles
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
What factors contribute to the stability of the joint?
Rotator cuff muscles
Glenoid labrum
Ligaments
Attachments of the supraspinatus?
Supraspinatus fossa on posterior surface of scapula
Greater tuberosity of humerus
Innervation of supraspinatus?
Suprascapular nerve
Actions of the supraspinatus?
First 15* of abduction
Attachments of infraspinatus?
Infraspinous fossa
Greater tubercle of humerus
Innervation of infraspinatus?
Suprascapular nerve
Actions of the infraspinatus?
Lateral rotation of the arm
Attachments of the subscapularis?
Subscapular fossa on costal surface of scapula
Lesser tubercle of humerus
Innervation of the subscapularis?
Upper and lower subscapular nerves
Action of the subscapularis?
Medially rotates the arm
Innervation of the teres minor?
Axillary nerve
Action of the teres minor?
Lateral rotation of the arm
What causes pain in rotator cuff tendonitis?
When the arm is abducted, the tendon of the supraspinatus muscle rubs against the coracoacromial arch.
Degenerative changes in the subacromial bursa and tendon cause friction.
What is the characteristic sign of rotator cuff tendonitis?
Painful arc - pain during middle of abduction
Which muscles carry out protraction and retraction of the scapula?
Protraction - serratus anterior
Retraction - (middle fibres of) trapezius and rhomboids
Which muscles carry out depression and elevation of scapula?
Elevation - trapezius, levator scapulae
Depression - relaxation of these muscles
Which muscles carry out lateral/upward rotation of scapula?
Lateral - Upper and lower fibres of trapezius
Medial (tilt glenoid cavity inferiorly) - latissimus dorsi, levator scapulae, rhomboids
What are the clinical effects of a torn supraspinatus tendon?
Failure of initiation of adduction in first 15 degrees
During adduction, limb will suddenly drop after 90 degrees
