3. Anatomy of the Shoulder Joint

Question 1

Glenohumeral joint

Answer 1

Humeral head and glenoid fossa

Highly mobile ball and socket joint

Very unstable joint due to large humeral head on shallow glenoid fossa

Question 2

Acromioclavicular joint

Answer 2

Junction between acromion and clavicle

Stabilised by acromioclavicular ligament

Commonly dislocated in sports injuries

Question 3

Ligaments of the shoulder region

Answer 3

Stabilize/support the shoulder region
- Very strong

1. Acromioclavicular
2. Coracoclavicular- Major stabilizing ligament, 2 parts sitting at right angles to each other
3. Coracoacromial- Forms arch to support for head of humerus & prevents superior dislocation
4. Glenohumeral- superior, middle and inferior parts

Question 4

Muscles that rotate the scapula during abduction

Answer 4

Upper and lower fibres of trapezius

Serratus anterior

Question 5

Muscles that rotate the scapula during adduction

Answer 5

Rhomboids

Levator scapulae

Question 6

Most common shoulder dislocation

Answer 6

95% anterior dislocation

-Humeral head descends inferiorly and ends up anterior

Question 7

Factors increasing stability

Answer 7

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

Question 8

Muscles involved in abduction

Answer 8

Rotation of scapula

• Upper and lower fibres of trapezius
• Serratus anterior

Deltoid

Supraspinatus

Question 9

Muscles involved in adduction

Answer 9

Rotation of scapula

• Lev scap
• Rhomboids

Lat dorsi

Pec Major

Question 10

Insertion point of supraspinatus, infraspinatus and teres minor

Answer 10

Greater tubercle

Question 11

Supraspinatus

• origin
• function
• innervation

Answer 11

supraspinous fossa
-initiate abduction
first 15 degrees
-Suprascapular nerve

Question 12

Infraspinatus

• origin
• function

Answer 12

• infraspinous fossa
• Lateral rotation of the arm at the glenohumeral joint
• Suprascapular nerve

Question 13

Teres minor

• origin
• function

Answer 13

• lateral border of the scapula

- lateral rotation of the at the glenohumeral joint

Question 14

Subcapsularis

• origin
• function

Answer 14

• subscapular fossa
• medial rotation of the arm at the glenohumeral joint
• Upper and lower subscapular nerves

Question 15

Teres major

• Origin
• Insertion
• Innervation
• Function

Answer 15

Origin: Inferior angle of scapula

Insertion: medial lip of bicipital groove

Innervation: Inferior subscapular nerve

Function: medial rotation, Stabilises the humerus during abduction (eccentric contraction)

Question 16

Nerve supply to the shoulder

Answer 16

Suprascapular nerve

from posterior cord of brachial plexus

Question 17

The axillary nerve supplies which muscles

Answer 17

deltoid and teres minor

Question 18

The radial nerve supplies which muscles

Answer 18

triceps brachii

Question 19

Origin of the long head of the biceps

Answer 19

supraglenoid tubercle

Question 20

Origin of the short head of the biceps

Answer 20

corocoid

Question 21

Suprascapular nerve

Answer 21

from superior trunk of brachial plexus

supplies the supraspinatus and infraspinatus muscles

Question 22

Latissimus dorsi

-Innervation

Answer 22

Thoracodorsal nerve

Question 23

Teres major

-Innervation

Answer 23

Lower subscapular nerve

Question 24

Deltoid Muscle

• Origin
• Insertion
• Innervation
• Function

Answer 24

Origin: spine of scapula, acromion, clavicle

Insertion: Deltoid tuberosity

Innervation: axillary nerve

Function:
posterior fibres- extension+lateral rotation

anterior fibres: flexion+medial rotation

Question 25

Triceps Muscle

• Origin
• Insertion
• Innervation
• Function

Answer 25

Origin:
long head: infraglenoid tubercle of scapula
medial and lateral head: posterior surface of humerus

insertion: olecranon

Innervation: radial nerve

Function: extension arm

Question 26

Which ligament prevents superior dislocation of the shoulder?

Answer 26

Coracoacromial ligament

Question 27

Rotator cuff injuries

Answer 27

Supraspinatus impingement as supraspinatus most commonly injured
most commonly injured due to limited space for tendon under coracoacromial arch

Question 28

Describe the anastomosis of axillary and subclavian arteries in the scapula

Answer 28

Axillary-subscapular-dorsal scapular-subclavian-thyrocervical trunk-suprascapular trunk

Question 29

Quadrangular space

-borders

Answer 29

• Teres minor, teres major, humerus, long head of triceps

- damage here most likely to affect axillary nerve