Shoulder Joint, Rotator Cuff Muscles and Shoulder Joint Muscles

Question 1

The glenohumeral joint is what type of joint

Answer 1

Synovial ball and socket where the ball is the head of the humerus and the socket is the glenoid cavity of the scapula.

Question 2

The rim of cartilage surrounding the socket is

Answer 2

The glenoid Labrum

Question 3

What is the function of the glenoid labrum

Answer 3

To reduce the disproportion of the surfaces of the joint

Question 4

What type of cartilage covers both of the articulating surfaces

Answer 4

Hyaline Cartilage

Question 5

The head of the humerus is much larger than the glenoid fossa, what is the reason for this

Answer 5

Giving the joint inherant stability

Question 6

The joint capsule

Answer 6

A fibrous sheath which encloses the structures of the joint. It extends from the anatomical neck of the humerus to the border of the glenoid fossa. The joint capsule is lax, creating greater mobility.

Question 7

Subacromial Bursa

Answer 7

Located inferiorly to the deltoid and the acromion, and superiorly to the supraspinatus tendon and the joint capsule. It supports the deltoid and supraspinatus muscles. Inflammation of this muscle can result in several shoulder problems.

Question 8

Subscapular bursa

Answer 8

Located between the subscapularis tendon and the scapula. It reduces wear and tear on the tendon during movement at the shoulder joint.

Question 9

The majority of the shoulder joint ligaments are

Answer 9

Thickenings of the joint capsule

Question 10

Glenohumeral Ligaments (superior, middle and inferior)

Answer 10

Consits of three bands, which run with the joint capsule from the glenoid fossa to the anatomical neck of the humerus. They act to stabilise the anterior aspect of the joint.

Question 11

Coracohumeral ligament

Answer 11

Attaches the base of the coracoid process to the greater tubercle of the humerus. It supports the superior part of the joint capsule.

Question 12

Transverse Humeral Ligament

Answer 12

This spans the distance between the two tubercles of the humerus. It holds the tendon of the long head of the biceps in the intertubercular groove.

Question 13

Coracoacromial Ligament

Answer 13

Runs between the acromion and the coracoid process of the scapula forming the coraco-acrimial arch. The structure overlies the shoulder joint preventing superior displacement of the humeral head.

Question 14

Common injury to damage the subacromial bursa

Answer 14

Subacromial bursitis

Question 15

Arterial supply to the glenohumeral joint

Answer 15

Anterior and posterior circumflex humeral arteries and the subscapular artery.

Question 16

Nerve supply to the glenohumeral joint

Answer 16

Axillary, suprascapular and lateral pectoral nerves.

Question 17

Extension of the shoulder

Answer 17

Upper limb backwards in a sagittal plane. This is produced by the posterior deltoid, latissimus dorsi, long head of triceps brachii and teres major

Question 18

Flexion of the shoulder

Answer 18

Upper limb forwards. Biceps brachii, pectoralis major, anterior deltoid and coracobrachilais

Question 19

Abduction of the shoulder

Answer 19

Away from the midline. The first 0-15 degrees of abduction is produced by the supraspinatus. The middle fibres of the deltoid are responsible for the next 15-90 degrees. Past 90 degrees, the scapula needs to be rotated to achieve abduction – that is carried out by the trapezius and serratus anterior.

Question 20

Adduction of the shoulder

Answer 20

Upper limb towards the body. Contraction of pectoralis major, latissimus dorsi and teres major.

Question 21

Medial Rotation

Answer 21

Rotation towards the midline so that the thumb is pointing medially. Subscapularis, pectoralis major, latissimus dorsi, teres major and anterior deltoid.

Question 22

Lateral Rotation

Answer 22

Rotation away from the midline so that the thumb is pointing laterally. Infraspinatus and teres minor.

Question 23

Factors that contribute to the mobility of the shoulder joint

Answer 23

Type of joint (ball and socket), bony surfaces (shallow glenoid cavity and large humeral head), laxity of the joint capsule.

Question 24

Factors that contribute to the stability of the shoulder joint

Answer 24

Rotator cuff muscles, glenoid labrum and the ligaments

Question 25

Rotator cuff muscles

Answer 25

These muscles surround the shoulder joint, attaching to the tubercles of the humerus, whilst also fusing with the joint capsule. The resting tone of these muscles act to "pull" the humeral head into the glenoid cavity.

Question 26

Glenoid Labrum

Answer 26

Fibrocartilaginous ridge surrounding the glenoid cavity. It deepens the cavity, reducing the risk of dislocation.

Question 27

Dislocation of the Shoulder Joint (anterior dislocation)

Answer 27

Caused by excessive extension and lateral rotation of the humerus. The humeral head is forced anteriorly and inferiorly - into the weakest part of the joint capsule.

Question 28

Rotator Cuff Tendonitis

Answer 28

Tendonitis refers to inflammation of the muscle tendons – usually due to overuse. Over time, this causes degenerative changes in the subacromial bursa, and the supraspinatus tendon. This increases friction between the structures of the joint. The characteristic sign of rotator cuff tendonitis is the ‘painful arc’ – pain in the middle of abduction, where the affected area comes into contact with the acromion.

Question 29

The nerves innervating the shoulder joint have what nerve roots

Answer 29

C5-6

Question 30

The rotator cuff muscles orinigate and attach where

Answer 30

The scapula to the humeral head.

Question 31

Movements of the glenohumeral joint caused by the rotator cuff muscles

Answer 31

Lateral rotation, medial rotation and abduction

Question 32

Supraspinatus

Answer 32

Originates from the supraspinous fossa of the scapula and attaches to the greater tubercle of the humerus. It is innervated by the suprascapular nerve. Actions - Abducts the arm

Question 33

Infraspinatus

Answer 33

Originates from the infraspinous fossa of the scapula and attaches to the greater tubercle of the humerus. Innervation: Suprascapular nerve Action: Laterally rotates the arm

Question 34

Subscapularis

Answer 34

Originates from the subscapular fossa and attaches to the lesser tubercle of the humerus. Innervation: Upper and lower subscapular nerves Actions: medially rotates the arm

Question 35

Teres Minor

Answer 35

Originates from the posterior surface of the scapula, adjacent to its lateral border. It attaches to the greater tubercle of the humerus. Innervation: Axillary Nerve Actions: Laterally Rotates the Arm

Question 36

Deltoid

Answer 36

Originates from the scapula and the clavicle, attaches to the deltoid tuberosity on the lateral surface of the humerus. Innervation: The axillary nerve Actions: Anterior fibres flex the shoulder, posterior fibres extend the arm at the shoulder, middle fibres abduct the arm

Question 37

Teres Major

Answer 37

Originates from the posterior surface of the inferior angle of the scapula. It attaches to the medial lip of the intertubercular groove of the humerus. Innervation: Lower subscapular nerve Actions: adducts at the shoulder and medially rotates the arm

Question 38

Pectoralis Major

Answer 38

Fibres originate from the medial third of the clavicle, the sternum and the ribs. It extends and medially rotates at the shoulder joint

Question 39

Deltopectoral Triangle

Answer 39

Between the deltoid and pectoralis major muscle, subclavian vein is found here.

Question 40

Nerve supply of serratus anterior

Answer 40

Long Thoracic Nerve

Question 41

What clinical sign is seen on injury of the long thoracic nerve

Answer 41

Scapular Winging

Question 42

When is the long thoracic nerve commonly injured

Answer 42

Breast surgery

Question 43

Innervation of Trapezius Muscle

Answer 43

Accessory Nerve

Question 44

Action of Latissimus Dorsi on the shoulder joint

Answer 44

Extension

Question 45

Innervation of the Latissimus Dorsi Muscle

Answer 45

Thoracodorsal Nerve

Question 46

Levator Scapulae

Answer 46

Originates from the transverse process of the C1-4 Vertebrae and attaches to the medial border of the scapula. Innervation: Dorsal Scapular Nerve Actions: Elevation of the scapula

Question 47

Rhomboid Major

Answer 47

Originates from the spinous processes of T2-5 and attaches to the medial border of the scapula Innervation: Dorsal Scapular Nerve Actions: Retracts and rotates the scapula

Question 48

Rhomboid Minor

Answer 48

Originates from the spinous processes of C7-T1 and attaches to the medial border of the scapula, at the level of the spine of the scapula. Innervation: Dorsal Scapular Nerve Actions: Retracts and rotates the scapula