Functional anatomy of the shoulder Flashcards
Bones of the shoulder
Scapula
Humerus
Clavicle
What type of bone is the scapula
Irregular
Anatomical neck of humerus
Site of attachment of capsule
Site of epiphyseal plate in childhood
Surgical neck of humerus
Between the tubercles and the shaft and more frequently fractured then anatomical neck
Articulation of shoulder girdle
Sternoclavicular
Acromioclaviculr
Glenohumeral
Scapulothoriacuc
What type of joint is the shoulder joint
Ball and socket
Synovial joint
Most mobile
Least stable
What deepens the glenoid cavity
Labrum
What is responsible for the mobility of the shoulder joint
Shallow glenoid fossa
Disproportion of articular surface
Lax capsule, especially inferiorly
What are the static stabilisers of the shoulder joint
Glenoid labrum
Joint capsule
Intracapsular ligaments
Extracapsular ligamements
Dynamic stabilisers of shoulder joint
Rotator cuff muscles
Muscles
- deltoid
- coracobrachialis
- long head of biceps
- long head of triceps
What are the intracapsular ligaments
3 glenohumeral ligaments
- superior
- middle
- inferior
What are the extracapsular ligaments
- coracoacromial ligament
- coracohumeral ligament
- transverse humeral ligament
- holds tendon of long head of biceps in place during shoulder movement
What is the coracoacromial arch comprised of
Coracoid process
Coracoacromial ligament
Acromion process
What does the coracoacromial arch prevent
Superior dislocation of the humerus
What are the muscles of the rotator cuff
SITS
Supraspinatus
Infraspinatus
Teres minor
Subscapular is
What muscles of the rotator cuff arise on the dorsal aspect of the scapula
Teres minor
Supraspinatus
Infraspinatus
All insert into greater tubercle of humerus
Which muscles arises from the ventral aspect of the scapula
Subscapularis inserts into lesser tubercle of humerus
Actions of rotator cuff muscles
Stabilise the shoulder joint, holding the head of the humerus in the glenoid cavity
Action of supraspinatus
Initiation and first 15 degrees of abduction
What nerve innervates the supraspinatus
Suprascapular nerve - C5,6
Action of infraspinatus
Lateral external rotation of arm
What nerve innervates the infraspinatus
Suprascapular nerve
C5,6
Action of teres minor
Lateral rotation of the arm, weak adductor
What nerve innervates the teres minor
Axillary nerve
C5,6
Action of subscapularis
Medial and internal rotation of the arm
What nerve innervates the subscapularis
Upper and lower subscapular nerves
C5,6
What other muscles stabilise the joint
Deltoid
Coracobrachialis
Long head of biceps
What is the subacromial space
Space between acromion and head of humerus 1-1.5 cm
Blood supply to shoulder joint
Anterior circumflex humeral artery
Posterior circumflex humeral artery
Suprascapular artery
What is responsible for 0-15 degrees of abduction at the glenohumeral joint
Supraspinatus
What is responsible for 15-90 degrees of abduction at the glenohumeral joint
Deltoid
What is responsible for rotation of scapula at scapulothororacic joint
Trapezium and serrated anterior
Nerve supply to deltoid
Axillary nerve
What do the anterior fibres of the deltoid do
Flex and internally rotate the arm at the shoulder
Central fibres of deltoid
Abduct the arm from 15-90 degrees takes over from supraspinatus
Posterior fibres of deltoid
Extend and laterally rotate the arm at the shoulder
What do the upper fibres of the trapezius do
Rotate acromion of scapula upwards during abduction of shoulder
Lower fibres of trapezius role
Rotate medial spine of scapula downwards
Action of serratus anterior
Protraction of scapula
Rotation of scapula during abduction of shoulder form 90 - 150 degrees
Nerve supply to serratus anterior
Long thoracic nerve
C5,6,7
What muscles extend the shoulder
Posterior fibres of deltoid- axillary C5,6
Lattisimus dorsi- thoracodorsal nerve C6, 7,8
Teres major - lower subscapular nerve C5, 6
What does lasttisimus dorsi do
Extends, adducts and medically rotates te shoulder
What does teres major do
Adducts, extends and medially rotates the shoulder
What muscles flex the shoulder
Clavicular head of pec major
Anterior fibres of deltoid
Coracobrachialis
Biceps brachii
Actions of biceps bracii
Weak contribution to flexion of shoulder
Strong supination of foreman
Flexor of elbow
Adduction of the shoulder
Pec major
Lattisimus dorsi
Teres major
Medial rotation of the shoulder
Sternocostal head of pec major
Subscapularis
Teres major
Lattisimus Doris
External rotation of shoulder
Infraspinatus
Teres minor
