Anatomy Of The Shoulder Joint Flashcards
What are the 3 main bones of the shoulder joint?
Clavicle
Scapula
Humerus
What are the 4 joints that make up the shoulder complex?
Sternoclavicular joint
Acromioclavicular joint
Glenohumeral joint
Scapulothoracic joint
What 2 joints of the shoulder complex make up the shoulder girdle?
Sternoclavicular joint
Acromioclavicular joint
What is the Sternoclavicular joint?
Where the sternum meets the clavicle
What is the Acromioclavicular joint?
Where the Acromium of the scapula meets the clavicle
What type of joint is the Sternoclavicular joint?
Synovial joint
Saddle type joint
The Sternoclavicular joint is highly mobile, why is dislocation rare?
Very strong ligament
What type of joint is the acromioclavicular joint?
Synovial joint
Plane type joint
What is the function of the acromioclavicular joint?
Helps move scapula around rib cage in protraction and retraction
What ligaments give the acromioclavicular joint lots of strength?
Coracoclavicular ligaments
What is the Scapulothoracic joint?
Not an actual bony articulation
Where scapula floats over the thorax
What is the Glenohumeral joint?
The head of the humerus in the Glenoid fossa of the scapula
Why is the Glenohumeral joint considered unstable?
The head of the humerus is relatively large so only a small portion of it is accepted into the glenoid fossa (shallow)
What helps reduce the instability of the Glenohumeral joint?
Glenoid labrum
What is the Glenoid labrum and its function?
Ring of Fibrocartilage that helps deepen the glenoid fossa maximising the amount of articulating surface area of the humeral head in the glenoid fossa
Where does the tough but loose fibrous joint capsule of the Glenohumeral joint run from?
The rim of the glenoid cavity glenoid labrum to the anatomical neck of the humerus and dips medially down to surgical neck of humerus
What reinforces the loose fibrous capsule of the Glenohumeral joint?
Glenohumeral ligaments
What ligament prevents the superior displacement of the humerus?
Coracoacromial ligament
What is the structure called that the coracoacromio ligament forms which prevents the superior displacement of the humerus?
Osseoligamentus arch
What is the technical term for describing the movement the shoulder does with shrugging and then relaxing?
Shrug = Elevation
Relaxing = Depression
What is another way of describing retracting of the shoulders/scapula?
ADduction
What is another way of describing protracting of the shoulders/scapula?
ABduction
What is the most superficial back muscle and what is its function?
Trapezium/trapezius/trapezoid
Rotates scapula
What is the origin and insertion of the trapezium?
Origin = Ligamentum Nuchae + Skull + Spinous processes C7 - T12
Insertion = Clavicle + Acromium and scapular spine of scapula
What is the origin of the levator scapulae?
Transverse processes of C1-C4
What is the insertion of the Levator scapulae?
Inner/medial border of the scapula
What is the origin of Rhomboid minor?
C7-T1 transverse process
What is the origin of rhomboid major?
T2-T5
Where do both the rhomboid major and rhomboid minor insert?
Medial border of scapula
What movement does rhomboid major and rhomboid minor allow for?
Retraction
What innervates both rhomboids (major and minor) and the Levator Scapulae?
Dorsal scapular nerve
What are the main movements that the Glenohumeral joint allow for?
Flexion + Extension
Abduction + Adduction
Medial + Lateral rotation
What parts of the joint capsule of the Glenohumeral joint are lax allowing for movement?
Anterior and inferior parts
How many intracapsular ligaments are there in the joint capsule of the Glenohumeral joint?
3
What are the 3 intracapsular ligaments of the Glenohumeral joint?
(Not visible from outside capsule)
Superior Glenohumeral Ligament (SGHL)
Middle Glenohumeral Ligament (MGHL)
Inferior Glenohumeral Ligament (IGHL)
Where do the 3 intracapsular ligaments (SGHL, MGHL and IGHL) run from and to?
Glenoid labrum to the Humerus
Which part of the fibrous joint capsule do the intracapsular ligaments reinforce and therefore prevent dislocation in which direction?
Anterior part of capsule
Prevents anterior dislocation
What are the 3 extracapsular ligaments of the shoulder joint?
Coracoacromial ligament (CAL)
Coracohumeral ligament
Transverse humeral ligament
Where does the coracoacromial ligament (CAL) run between?
Acromion (scapula) and coracoid process (scapula)
Where does the Coracohumeral ligament run between?
Base of coracoid process (Scapula) to anterior part of greater tubercle (humerus)
What is the function of the corcoacromial ligament and the Coracohumeral ligament?
Prevent upward displacement of joint
Why is the coracoacromial ligament significant?
Forms coraco-acromial arch which prevents superior dislocation of the humeral head
Where does the Transverse humeral ligament run between?
Sits across bicipital/intertubercular groove
Where is the intertubercular/bicipital groove?
On humerus between the greater and lesser tubercles
What is the function of the transverse humeral ligament?
Holds the tendon of the long head of biceps in place in the intertubercular groove during shoulder movement
What is the Coraco-Acromial arch?
Strong Osteo-Ligamentous structure composed of:
-Coracoacromial ligament
-Acromion
-Coracoid process
Overlies humeral head prevent upper displacement of the humerus
What are the 4 muscles that blend with the joint capsule to the humerus to strengthen the capsule?
Rotator cuff muscles:
-Supraspinatus
-Infraspinatus
-Teres minor
-Subscapularis
How do the rotator cuff muscles stabilise the shoulder joint?
Their tone helps hold head of humerus in glenoid cavity
What is a bursa?
A fluid filled sac found between two moving surfaces that contains lubricating fluid
What are 2 clinically important shoulder joint bursae?
Subacromial bursa
Subscapular bursa
What is the function of the subacromial bursa?
Reduce friction underneath deltoid allowing for free motion of rotator cuff tendons
What is subacromial bursitis and how does this present?
Inflammation of the subacromial bursa
Shoulder pain
Where is the subacromial bursa?
Below acromion and deltoid
Where is the subcoracoid bursa?
Below coracoid process
Where is the subscapular process?
Between scapular and Subscapularis tendon
What is the function of the subscapular bursa?
Reduce friction/wear and tear of the Subscapularis tendon
What muscle does internal rotation of Glenohumeral joint?
Teres minor (axial nerve)
What 4 muscles contribute to internal rotation of the Glenohumeral joint?
Sternal head of Pectoralis major (Medial and Lateral pectoral nerves)
Subscapularis (Upper + Lower subscapular nerves)
Teres major (Lower subscapular nerve)
Latissimus dorsi (Thoracodorsal nerve)
What is the origin of the Sternal head of Pectoralis major?
Originates from the anterior surface of the sternum, the superior six costal cartilages and the aponeurosis of the external oblique muscle.
What is the origin of Latissimus dorsi?
Lower part of the trunk of the back:
T6-T12 spinous processes, thoracolumbar fascia, iliac crest, and the inferior three ribs.
What is the insertion of Latissimus dorsi?
Fibres converge into tendon inserts at Intertubercular groove
What muscles are involved of Abduction of the shoulder joint?
Supraspinatus (initiates)
Deltoid (takes it to 90º)
Trapezius (upper fibres) and serratus anterior (rotate scapula)
What joint does rotation of the scapula for shoulder abduction happen at?
Scapulothoracic joint
What is the origin of the Deltoid?
Lateral 1/3 of clavicle
Acromion (scapula)
Spine of scapula
Where does the deltoid insert?
Deltoid tuberosity on the Humerus
What innervates the deltoid?
Axial nerve
What muscles do Adduction of the shoulder joint?
Pectoralis major (medial and lateral pectoral nerves)
Latissimus dorsi (thoracodorsal nerve)
Teres major (lower subscapular)
Coracobrachialis
What innervates coracobrachialis?
Musculocutaneous nerve
What innervates Latissimus dorsi?
Thoracodorsal nerve
What does extension of the shoulder joint (moving arms behind us)?
Deltoid (posterior fibres)
Latissimus dorsi
Teres major
Long head of triceps (Radial nerve)
What innervates long head of triceps?
Radial nerve
What is the origin of the clavicular head of Pectoralis major?
Anterior surface of medial clavicle
What is the insertion of the clavicular head of Pectoralis major?
Intertubercular groove with sternal costal head of Pectoralis major
What does Flexion at the shoulder joint?
Clavicular head of Pectoralis major
Anterior fibres of Deltoid
Coracobrachialis
Biceps brachii
What are both the coracobrachialis and biceps brachii innervated by?
Musculocutaneous nerve
What is the blood supply to the shoulder joint?
Anterior and Posterior humeral arteries
Suprascapular artery
What artery does the brachial artery come from?
Subclavian artery
What is the nerve supply to the shoulder joint?
(Think Hiltons law)
Axial nerve
Suprascapular
Lateral pectoral nerves
What innervates infraspinatus?
Suprascapular nerve
