Anatomy of the shoulder region

Question 1

Skeletal components of the pectoral girdle

Answer 1

• Clavicle

- Scapula

Question 2

Two key joints in the shoulder

Answer 2

• Glenohumeral joint

- Acromioclavicular joint

Question 3

Ligaments of the shoulder region

Answer 3

Stabilise/support the shoulder region - very strong

• Coracoclavicular
• Acromioclavicular
• Coracoacromial
• Glenohumeral (superior, middle, inferior)

Attachments are all in the name

Question 4

Features of coracoclavicular and coracoacromial ligaments

Answer 4

Coracoclavicular - two parts, major stabilising ligament

Coracoacromial - forms arch, provides support for head of humerus, prevents superior dislocation

Question 5

Features of the glenohumeral joint

Answer 5

Highly mobile ball and socket joint

• Abduction/adduction
• Flexion/extension
• Lateral/medial rotation
• Circumduction

Question 6

Function of the deltoid

Answer 6

• Abduction of the arm

Question 7

Deltoid - origin

Answer 7

• Spine of scapula + acromion + clavicle

Question 8

Deltoid - insertion

Answer 8

• Deltoid tuberosity

Question 9

Innervation of the deltoid

Answer 9

Supplied by axillary nerve
Posterior fibres - extension + lateral rotation

Anterior fibres - flexion + medial rotation

Question 10

Which muscles perform adduction of the arm

Answer 10

• Performed by latissimus dorsi and pectoralis major

Question 11

Joints involved in abduction/adduction of the arm

Answer 11

• Glenohumeral joint accommodates parts of movement

- Rotation of scapula increases range of movement

Question 12

Other muscle fibres involved in abduction

Answer 12

• Upper fibres of trapezius
• Lower fibres of trapezius
• Serratus anterior (for lateral rotation of scapula)

Question 13

Other muscle fibres involved in adduction

Answer 13

• Levator scapulae

- Rhomboids

Question 14

Muscles involved in the flexion of the arm

Answer 14

• Short head of biceps
• Long head of biceps
• Coracobrachialis
• Brachialis - flexes forearm
• Anterior fibres of deltoid

Question 15

Muscles involved in extension of arm

Answer 15

• Long head of triceps
• Lateral head of triceps(extend forearm)
• Medial head of triceps(extend forearm)
• Posterior fibres of deltoid
• Latissimus dorsi

Question 16

Why is the glenohumeral joint unstable

Answer 16

• Large humeral head
• Shallow glenoid fossa
• Most frequently dislocated joint - anterior dislocation common (humeral head descends inferiorly and ends up anterior)

Question 17

Factors which increase glenohumeral joint stability

Answer 17

1. Coracoacromial arch
2. Glenohumeral ligaments
3. Deepening of glenoid fossa by glenoid labrum
4. Long heads of biceps (above) and triceps (below)
5. Tendons of rotator cuff muscles

Question 18

What does the coracocromial arch prevent

Answer 18

• Prevents superior dislocation

Question 19

What do the glenohumeral ligaments support

Answer 19

• Supports anterior of joint

Question 20

How does the glenoid labrum increase glenohumeral stability

Answer 20

• Deepens glenoid fossa

Question 21

Long head of biceps - origin

Answer 21

• Supraglenoid tubercle

- Long head biceps passes through joint capsule of the transverse humeral ligament

Question 22

Long head of triceps - origin

Answer 22

• Infraglenoid tubercle

Question 23

Features of the rotator cuff muscles

Answer 23

• Four muscles
• Insert on humerus close to joint
• Fuse with the joint capsule
• Forms cuff around joint

Question 24

Which sides do the rotator cuff muscles surround

Answer 24

• Rotator cuff muscles surround on all sides except inferiorly

Question 25

What is the subacromial bursa

Answer 25

- The subacromial bursa is the synovial cavity located just below the acromion, which communicates with the subdeltoid bursa

Question 26

Rotator cuff muscles - insertion

Answer 26

- Supraspinatus, infraspinatus and teres minor insert into the greater tubercle

Question 27

Rotator cuff function

Answer 27

Together: stabilise humeral head on glenoid fossa Supraspinatus - initiate abduction Infraspinatus - lateral rotation Teres minor - lateral rotation Subscapularis - medial rotation

Question 28

Function of teres major

Answer 28

- Should also be considered with the rotator cuff muscles - Performs medial rotation - Stabilised the humerus during abduction (eccentric contraction)

Question 29

Rotator cuff injuries

Answer 29

Supraspinatus impingement: - Supraspinatus most commonly injured - Limited space for tendon under coracoacromial arch - Impingement due to repetitive overhead activities (common in athletes such as throwers)

Question 30

Blood supply to the rotator cuff

Answer 30

- Rich blood supply - Scapula anastomosis - Allows continuous supply of blood to shoulder region during movement - From subclavian and axillary arteries

Question 31

What is the scapular anastomosis(memorise diagram)

Answer 31

- The scapular anastomosis is a system connecting certain subclavian artery and their corresponding axillary artery, forming a circulatory anastomosis around the scapula - It allows blood to flow past the joint in case of occlusion, damage, or pinching of specific scapular arteries

Question 32

Nerve supply to the shoulder

Answer 32

From the brachial plexus - suprascapular nerve(supraspinatus and infraspinatus)

Question 33

Location of the cords of the brachial plexus

Answer 33

- Within axilla | - Below pectoralis minor

Question 34

Specific innervation of deltoid and teres minor + triceps brachii

Answer 34

Posterior cord: Axillary - deltoid and teres minor Radial - triceps brachii

Question 35

Specific innervation of subscapularis, teres major and thoracodorsal nerve

Answer 35

Upper and lower subscapular nerves - subscapularis, teres major Thoracodorsal nerve - latissimus dorsi

Question 36

Boundaries of the quadrangular space

Answer 36

above/superior: the teres minor (inferior margin). below/inferior: the teres major (superior margin) medially: the long head of the triceps brachii (lateral margin) laterally: the surgical neck of the humerus anteriorly: the subscapularis

Question 37

What can a fracture of the surgical neck of the humerus result in

Answer 37

- Possible damage to the axillary nerve and posterior circumflex humeral artery

Question 38

Which branch of the lateral cord of the brachial plexus supplies pectoralis major

Answer 38

- Lateral pectoral nerve

Question 39

Branches of the medial cord that innervate pec major and minor

Answer 39

- Medial pectoral nerve (pectoralis major and minor) | - Medial cutaneous nerves to arm and forearm