The Shoulder Flashcards
What are the origins of pectoralis major?
Clavicular head
- from the medial half of the anterior surface of the clavicle
Sternocostal head
- anterior surface of the sternum
- upper 6 costal cartilages
- External Oblique Aponeurosis
Where is the insertion of the pectoralis major?
Humerus (lateral ITG) (lateral lip of bicipital groove)
What are the actions of pectoralis major?
- Adduction and medial rotation of the arm (the whole muscle)
- Clavicular head: flexion of the arm
- Sternocostal head: extends the flexed arm
- Acts as accessory respiratory muscle by elevating the ribs
What is the innervation of the pectoralis major muscle?
Medial (C8-T1) and Lateral (C5-C7) pectoral nerves
What is the origin of the trapezius muscle?
- SP C7-T12
- Occipital protuberance
- Ligamentum nuchae
Where is the insertion of trapezius?
Clavicle, scapula (acromion spine)
What is the action of trapezius?
Rotating the scapula
What is the innervation of trapezius
CN XI
Where is the origin of serratus anterior?
Ribs 1-9
Where is the insertion of serratus anterior?
Scapula (ventral medial)
What is the action of serratus anterior?
Prevents winging of the scapula
What is the innervation of serratus anterior?
Long thoracic nerve
What are the origins of deltoid?
Lateral clavicle
scapula
Where is the insertion for deltoid?
Humerus (deltoid tuberosity)
What is the action of deltoid?
Anterior fibres - flexion and medial rotation
Posterior fibres - extension and lateral rotation
Middle fibres - major abductor of the arm (after 15 degrees)
What is the origin for subscapularis?
Ventral scapula (subscapular fossa)
Where does the subscapularis insert?
Humerus (LT)
What is the action of subscapularis?
Internally rotates the arm
Provides anterior stability
What is the innervation of the subscapularis?
Superiorand Inferior subscapular nerves
Where is the origin of supraspinatus?
Superior scapula (supraspinatus fossa)
Where does the supraspinatus insert?
Humerus (greater tuberosity)
What are the action of supraspinatus?
Abducting
Providing stability
Externally rotating the arm
What is the innervation of supraspinatus?
Suprascapular nerve
Where is the origin of infraspinatus?
Dorsal scapula (infraspinatus fossa)
Where is the insertion of infraspinatus?
Humerus (greater tuberosity)
What is the action of infraspinatus?
Provides stability
Externally rotates the arm
What is the innervation of infraspinatus?
Suprascapular nerve
Where is the origin of Teres minor?
Scapula (dorsolateral)
Where does teres minor insert?
Humerus (greater tuberosity)
What is the action of teres minor?
Providing stability
externally rotating the arm
What is the innervation of teres minor?
Axillary nerve
What are the borders of the triangular interval?
Superior - teres major
Medial - long head of triceps
Lateral - lateral head of triceps
What structures are found in the triangular interval?
Radial nerve
Deep artery of the arm
What are the borders of the triangular space?
Superior - teres minor
Inferior - teres major
Lateral - long head of triceps
What passes through the triangular space?
Circumflex scapular artery
What are the boundaries of the quadrangular space?
Superior - teres minor
Inferior - teres major
Medial - long head of triceps
lateral - medial border of humerus
What structures pass through the quadrangular space?
Axillary nerve
posterior humeralcircumflex artery
What divides the axillary artery into parts?
the pectoralis minor
1st part medial to pec minor
2nd part deep to pec minor
3rd part lateral to pec minor
What are the branches of the axillary artery?
Screw the Lawyer, Save a Patient
Superior thoracic artery (1st part)
Thoracoacromial artery (2nd part)
Lateral thoracic (2nd part)
Subscapular artery (largest branch - from 3rd part)
Anterior humeral circumflex artery (3rd part)
Posterior humeral circumflex artery (3rd part)
What is the course of the superior thoracic artery?
Medial to serratus anterior and pectoral muscles
What is the course of thoracoacromial artery?
Has four branches - deltoid, acromial, pectoralis, clavicular
What is the course of lateral thoracic artery
Descends to serratus anterior
What is the course of subscapular artery?
Have two branches - thoracodorsal and circumflex scapular
What is the course of the anterior humeral circumflex atery?
Supplies blood to the humeral head - arcuate artery lateral to the bicipital groove
What is the course of the posterior humeral circumflex artery?
Branch in the quadrangular space accompanying the axillary nerve
What are the surface markings of the coracoid process?
Can be felt 2cm inferior to the junction between the middle and lateral thirds of the clavicle
What structures attach to the coracoid process>
Ligaments
- coracoclavicular
- coracoacromial
- coracohumeral
Muscles
- pectoralis minor (insertion)
- coracobrachialis (origin)
- short head of biceps (origin)
What muscle insert into the bicipital groove?
Lady between two majors
Teres major (Medial lip)
Latissimis dorsi (floor)
Pectoralis major (lateral lip)
Tendon of the long head of biceps runs in the grooveh
Which muscles are responsible for shoulder abduction?
Supraspinatus (0-15)
Deltoid middle fibres (15-90)
Trapezius and serratus anterior (>90) which will require upward rotation of the scapula with lateral rotation of the humerus
Which factors decrease the stability of the shoulder?
Shallow glenoid cavity
Lax capsule with few ligaments
inferior aspect is not supported due to the presence of quadrangular space
What are the main stabilisers of the shoulder joint?
Rotator cuff muscles
What sensory features does the axillary nerve have?
Provides sensation to the skin to the lower half of the deltoid (regimental badge)
What motor supply does the axillary nerve provide?
Deltoid and teres minor
What does injury to the axillary nerve result in
Inability to abduct the shoulder over 15 degrees
loss of sensation over the badge area
