The Shoulder

Question 1

What are the origins of pectoralis major?

Answer 1

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

Question 2

Where is the insertion of the pectoralis major?

Answer 2

Humerus (lateral ITG) (lateral lip of bicipital groove)

Question 3

What are the actions of pectoralis major?

Answer 3

• 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

Question 4

What is the innervation of the pectoralis major muscle?

Answer 4

Medial (C8-T1) and Lateral (C5-C7) pectoral nerves

Question 5

What is the origin of the trapezius muscle?

Answer 5

• SP C7-T12
• Occipital protuberance
• Ligamentum nuchae

Question 6

Where is the insertion of trapezius?

Answer 6

Clavicle, scapula (acromion spine)

Question 7

What is the action of trapezius?

Answer 7

Rotating the scapula

Question 8

What is the innervation of trapezius

Answer 8

CN XI

Question 9

Where is the origin of serratus anterior?

Answer 9

Ribs 1-9

Question 10

Where is the insertion of serratus anterior?

Answer 10

Scapula (ventral medial)

Question 11

What is the action of serratus anterior?

Answer 11

Prevents winging of the scapula

Question 12

What is the innervation of serratus anterior?

Answer 12

Long thoracic nerve

Question 13

What are the origins of deltoid?

Answer 13

Lateral clavicle
scapula

Question 14

Where is the insertion for deltoid?

Answer 14

Humerus (deltoid tuberosity)

Question 15

What is the action of deltoid?

Answer 15

Anterior fibres - flexion and medial rotation
Posterior fibres - extension and lateral rotation
Middle fibres - major abductor of the arm (after 15 degrees)

Question 16

What is the origin for subscapularis?

Answer 16

Ventral scapula (subscapular fossa)

Question 17

Where does the subscapularis insert?

Answer 17

Humerus (LT)

Question 18

What is the action of subscapularis?

Answer 18

Internally rotates the arm
Provides anterior stability

Question 19

What is the innervation of the subscapularis?

Answer 19

Superiorand Inferior subscapular nerves

Question 20

Where is the origin of supraspinatus?

Answer 20

Superior scapula (supraspinatus fossa)

Question 21

Where does the supraspinatus insert?

Answer 21

Humerus (greater tuberosity)

Question 22

What are the action of supraspinatus?

Answer 22

Abducting
Providing stability
Externally rotating the arm

Question 23

What is the innervation of supraspinatus?

Answer 23

Suprascapular nerve

Question 24

Where is the origin of infraspinatus?

Answer 24

Dorsal scapula (infraspinatus fossa)

Question 25

Where is the insertion of infraspinatus?

Answer 25

Humerus (greater tuberosity)

Question 26

What is the action of infraspinatus?

Answer 26

Provides stability Externally rotates the arm

Question 27

What is the innervation of infraspinatus?

Answer 27

Suprascapular nerve

Question 28

Where is the origin of Teres minor?

Answer 28

Scapula (dorsolateral)

Question 29

Where does teres minor insert?

Answer 29

Humerus (greater tuberosity)

Question 30

What is the action of teres minor?

Answer 30

Providing stability externally rotating the arm

Question 31

What is the innervation of teres minor?

Answer 31

Axillary nerve

Question 32

What are the borders of the triangular interval?

Answer 32

Superior - teres major Medial - long head of triceps Lateral - lateral head of triceps

Question 33

What structures are found in the triangular interval?

Answer 33

Radial nerve Deep artery of the arm

Question 34

What are the borders of the triangular space?

Answer 34

Superior - teres minor Inferior - teres major Lateral - long head of triceps

Question 35

What passes through the triangular space?

Answer 35

Circumflex scapular artery

Question 36

What are the boundaries of the quadrangular space?

Answer 36

Superior - teres minor Inferior - teres major Medial - long head of triceps lateral - medial border of humerus

Question 37

What structures pass through the quadrangular space?

Answer 37

Axillary nerve posterior humeralcircumflex artery

Question 38

What divides the axillary artery into parts?

Answer 38

the pectoralis minor 1st part medial to pec minor 2nd part deep to pec minor 3rd part lateral to pec minor

Question 39

What are the branches of the axillary artery?

Answer 39

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)

Question 40

What is the course of the superior thoracic artery?

Answer 40

Medial to serratus anterior and pectoral muscles

Question 41

What is the course of thoracoacromial artery?

Answer 41

Has four branches - deltoid, acromial, pectoralis, clavicular

Question 42

What is the course of lateral thoracic artery

Answer 42

Descends to serratus anterior

Question 43

What is the course of subscapular artery?

Answer 43

Have two branches - thoracodorsal and circumflex scapular

Question 44

What is the course of the anterior humeral circumflex atery?

Answer 44

Supplies blood to the humeral head - arcuate artery lateral to the bicipital groove

Question 45

What is the course of the posterior humeral circumflex artery?

Answer 45

Branch in the quadrangular space accompanying the axillary nerve

Question 46

What are the surface markings of the coracoid process?

Answer 46

Can be felt 2cm inferior to the junction between the middle and lateral thirds of the clavicle

Question 47

What structures attach to the coracoid process>

Answer 47

Ligaments - coracoclavicular - coracoacromial - coracohumeral Muscles - pectoralis minor (insertion) - coracobrachialis (origin) - short head of biceps (origin)

Question 48

What muscle insert into the bicipital groove?

Answer 48

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

Question 49

Which muscles are responsible for shoulder abduction?

Answer 49

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

Question 50

Which factors decrease the stability of the shoulder?

Answer 50

Shallow glenoid cavity Lax capsule with few ligaments inferior aspect is not supported due to the presence of quadrangular space

Question 51

What are the main stabilisers of the shoulder joint?

Answer 51

Rotator cuff muscles

Question 52

What sensory features does the axillary nerve have?

Answer 52

Provides sensation to the skin to the lower half of the deltoid (regimental badge)

Question 53

What motor supply does the axillary nerve provide?

Answer 53

Deltoid and teres minor

Question 54

What does injury to the axillary nerve result in

Answer 54

Inability to abduct the shoulder over 15 degrees loss of sensation over the badge area