Session 7: Functional Anatomy of the Shoulder

Question 1

What does the shoulder girdle consist of?

Answer 1

The clavicle and the scapula.

Question 2

What is the shoulder joint called?

Answer 2

The glenohumeral joint.

Question 3

What are the other joints in the shoulder girdle?

Answer 3

Sternoclavicular joint and the acromioclavicular joint.

Question 4

Articulations of the glenohumeral joint.

Answer 4

The glenoid fossa of the scapula and the head of the humerus.

Question 5

What is the scapulothoracic joint?

Answer 5

Articulation of the scapula with the thoracic wall however this is not a true joint.

Question 6

Features of the glenohumeral joint.

Answer 6

The humeral head is larger than the glenoid fossa (golf ball sitting on a tee).

Ball and socket joint + synovial joint.

Large range of movement. Great flexibility and mobility at the expense of lower stability.

Question 7

What is the anatomical neck of the humerus?

Answer 7

Obliquely directed forming an obtuse angle with the body of the humerus.
It’s between the head of the humerus and the great tubercle/lesser tubercle region.

Question 8

What attaches on the anatomical neck?

Answer 8

The articular capsule of the shoulder joint. Also marks the region of the epiphyseal growth plate during the growth in length of the humerus in childhood.

Question 9

What is the surgical neck of the humerus?

Answer 9

A constriction below the tubercles of the greater tubercle and lesser tubercle.
Much more frequently fractured than the anatomical neck of the humerus.

Question 10

What can a fracture in the area of the surgical neck cause?

Answer 10

Damage to axillary nerve and posterior circumflex humeral artery.

Question 11

What is the glenoid labrum?

Answer 11

An additional rim of fibrocartilaginous tissue around the edge of the glenoid cavity.
Functions to deepen the socket and reduce the risk of dislocation.

Question 12

What reinforces the joint capsule of the glenohumeral joint?

Answer 12

The rotator cuff muscles + ligaments.

Question 13

Where is the glenohumeral joint the weakest?

Answer 13

At its inferior aspect because of no reinforcement.

Question 14

There are three ligaments of the glenohumeral joint. Which?

Answer 14

Superior GHL
Middle GHL
Inferior GHL

Question 15

Where can the ligaments of GHJ be found?

Answer 15

On the anterior aspect of the joint which reduces the risk of anterior dislocation which is the most common direction of dislocation of the shoulder.

Question 16

What are the other ligaments of the shoulder region?

Answer 16

Conoid ligament and trapezoid ligament which form the coracoclavicular ligament linking the coracoid process of the scapula to the clavicle.

Coracohumeral ligament linking the coracoid process of the scapula and the greater tubercle of the humerus.

Transverse humeral ligament.

Coraco-acromial ligament.

Question 17

Features of the transverse humeral ligament.

Answer 17

Creates a tunnel between the greater and lesser tuberosities of the humerus to allow passage of the long head of the biceps.

Question 18

Features of the coraco-acromial ligament.

Answer 18

Provides the roof of the subacromial space which is a tunnel above the glenohumeral joint that allows passage of the supraspinatus tendon. This ligament prevents superior dislocation of the humerus when a person falls onto their outstretched hand.

Question 19

Rotator cuff muscles.

Answer 19

SITS
Supraspinatus
Infraspinatus
Teres minor
Subscapularis

Question 20

Innervation and action of supraspinatus.

Answer 20

Suprascapular nerve C5,C6. First 15 degrees of abduction.

Question 21

Innervation and action of infraspinatus.

Answer 21

Suprascapular nerve C5, C6 lateral rotation.

Question 22

Innervation and action of teres minor.

Answer 22

Axillary nerve C5, C6 lateral rotation and adduction.

Question 23

Innervation and action of subscapularis.

Answer 23

Upper and lower subscapular nerves C5, C6 medial rotation.

C5 is responsible for shoulder abduction and lateral rotation

Question 24

Bursae of the shoulder girdle.

Answer 24

Subacromial bursa

Subscapular bursa

Question 25

Features of the subacromial bursa.

Answer 25

Lies under the acromion.
Separates the supraspinatus tendon from the overlying coraco-acromial ligament, the acromion, the coracoid process and from the deep surface of the deltoid muscle.

Acts like a cushion and reduces friction as the supraspinatus tendon passes under theses structures.

Question 26

Features of the subscapular bursa.

Answer 26

Located between the tendon of subscapularis and the neck of the scapula. Protects the subscapularis tendon as it passes inferior to the root of the coracoid process and over the neck of the scapula.

Question 27

What is the coraco-acromial arch?

Answer 27

An arch formed by the coracoid process, coraco-acromial ligament and the acromion.

Question 28

What is the subacromial space?

Answer 28

The space between the coraco-acromial arch, and the head of the humerus.

Question 29

What can be found in the subacromial space?

Answer 29

Subacromial bursa
Supraspinatus tendon
Joint capsule
Long head of biceps

Question 30

What is impingement syndrome of the subacromial space?

Answer 30

During abduction there is the potential for impingement of these soft tissues leading to irritation and inflammation.

Question 31

Where does the first 90 degrees of shoulder abduction occur?

Answer 31

At the glenohumeral joint.

Question 32

Which muscle performs 0-15 degrees of shoulder abduction?

15-90 degrees?

Answer 32

0-15 = Supraspinatus (suprascapular nerve)
15-90 = Deltoid (axillary nerve)

Question 33

Where does shoulder abduction over 90 degrees occur?

Which muscles are involved?

Answer 33

At the scapulothoracic ‘joint’.

Rotation of the scapula due to upper fibres of the trapezius and serratus anterior.

Question 34

Muscles responsible for adduction of the shoulder.

Answer 34

Pectoralis major
Latissimus dorsi
Teres major

Question 35

Muscles responsible for flexion of the shoulder.

Answer 35

Anterior fibres of deltoid
Clavicular head of pectoralis major
Coracobrachialis
Biceps brachii

Question 36

Extension of the shoulder.

Answer 36

Posterior fibres of deltoid
Latissimus dorsi
Teres major

Question 37

Medial rotation of the shoulder.

Answer 37

Subscapularis
Teres major
Sternal head of pectoralis major
Latissimus dorsi.

Question 38

External rotation of the shoulder.

Answer 38

Infraspinatus

Teres minor

Question 39

Route of the axillary artery.

Answer 39

When the subclavian artery crosses the lateral border of the first rib to enter the axilla it becomes the axillary artery.

The axillary artery passes behind pectoralis minor at the level of the surgical neck of the humerus and gives of the anterior and posterior circumflex humeral arteries.

The axillary artery then becomes the brachial artery at the inferior border of teres major.

Question 40

Where can you find the anterior and posterior circumflex humeral arteries?

Answer 40

They encircle the neck of the humerus and supply the shoulder region.

Question 41

What is the arterial supply of the shoulder joint?

Answer 41

Derived from anterior and posterior circumflex humeral arteries as well as the suprascapular artery.

Question 42

Factors contributing to the stability of the shoulder joint (GHJ)

Answer 42

Glenoid labrum
Congruency of the humeral head and the glenoid cavity
Glenohumeral ligaments
Extra-capsular ligaments like coracoacromial arch superiorly (coracoacromial ligament) and the coracohumeral ligament as well superiorly.

Rotator cuff muscles
Extrinsic muscles that cross the shoulder joint like biceps brachii, triceps brachii, deltoid, pectoralis major, coracobrachialis.