Upper limb : Shoulder joint

Question 1

what are the features of the scapula?

Answer 1

• irregular bone.

Question 2

what are the features of the humerus?

specifically what is the difference in anatomical vs surgical neck.

Answer 2

• anatomical neck : site of attachment to capsule, site of epiphyseal plate.
• surgical neck : between tubercles and shaft, and more fractures than anatomical neck.

Question 3

what are some features of the clavicle?

Answer 3

• sternal end articulates with manubrium of sternum towards midline of body : sternoclavicular joint.
• acromial end articulates with acromion of scapula : acromioclavicular joint.

Question 4

what are some features of the glenohumeral joint?

Answer 4

• the shoulder joint is a synovial joint, with ball and socket design.
• most mobile with wide range of movement over multiple planes.
• least stable joint in body : most common dislocations.
• articular surfaces head of humerus to glenoid fossa, 4:1 disproportional.

Question 5

what is the significance of the glenoid labrum?

Answer 5

• deepens glenoid fossa, with loose anterosuperior attachment and inferior firm attachment.
• proprioceptive nerve endings ( perceiving movement ) found in GH ligaments and labrum so disruption leads to decrease in that.
• site of GH ligament attachment.

Question 6

what is responsible for the mobility of the shoulder joint?

Answer 6

• shallow glenoid fossa.
• disproportion of articular surface.
• lax capsule : relaxed.

Question 7

name some static stabilisers of the shoulder joint.

Answer 7

• glenoid labrum.
• joint capsule.
• intracapsular ligaments.
• extracapsular ligaments.

Question 8

name some dynamic shoulder stabilisers.

Answer 8

• rotator cuff muscles.

- other muscles : deltoid, corabrachialis, long head of biceps and triceps.

Question 9

what are the features of the capsule at the shoulder?

Answer 9

• attached to glenoid labrum, margining fossa and anatomical neck of humerus from other side.
• medially dips to surgical neck.
• tough but lax to allow movement.
• small opening with synovial membrane.

Question 10

what is the significance of the synovial membrane?

Answer 10

• lines the capsule, intracapsular bone to articular cartilage, covers tendon of long head of bicep within joint cavity.

Question 11

what are the intracapsular ligaments?

Answer 11

• 3 glenohumeral ligaments : superior, middle or inferior glenohumeral ligament.
• 3 fibrous band from glenoid labrum to humerus, reinforces capsule anteriorly.
• can be seen from inside the capsule.

Question 12

what are the extracapsular ligaments?

Answer 12

• caracoacramial : caracoid to acromion.
• carocohumeral : caracoid to anteior greater tubercule.
• transverse HL : holds tendon of long biceps head in place when shoulder moves.

Question 13

what is the caracoacromial arch?

Answer 13

• structure comprises caracoid process, caracoacromial ligament and acromian process.
• prevents superior dislocation of humerus.
• IMPINGEMENT SYNDROME.

Question 14

what muscles make up the rotator cuff? and whats the significance?

Answer 14

• supraspinatus, infraspinatus, teres minor, subscapularis (dorsal unlike others).
• important in contributing to stability as the cuff fuses with capsule and strengthens it holding humeral head in glenoid cavity.
• subacromial bursa separates suprapinatus from caracoacromial arch.

Question 15

what are the actions of the rotator cuff muscles?

Answer 15

• supraspinatus : initiation and first 15 of abduction.
• infraspinatus : lateral.external rotation of arm.
• teres minor : lateral arm rotation.
• sunscapularis : medial/ internal rotation.

*also stabilised by deltoid, long biceps head, long biceps head, caracobrachialis.

Question 16

what are the significance of shoulder bursae?

Answer 16

• subacromial bursa : facilitates supraspinatus tendon under coracoacromial arch and deltoid movement.
• subscapula bursa : facilitates subscapularis tendon over scapula

Question 17

what does the aubacromial space contain?

Answer 17

• subacromial bursa, supraspinatous tendon, capsule, tendon of long head of biceps.

Question 18

what nerves and arteries supply the shoulder joint?

Answer 18

• nerves : axillary, suprascapular, lateral pectoral nerve from brachial plexus C5, C6.
• blood : anterior circumflex humeral, posterior circumflex humeral, suprascapular artery.

Question 19

what muscles are responsible for shoulder abduction?

think in 0-15, 15-90 and 90-150 degrees

Answer 19

first 90 : across glenohumeral joint.

• 0-15 : supraspinatus (suprascapular nerve)
• 15-90 : deltoid central fibres (axillary nerve)

90-150 : across scapulothoracic joint.
- rotation of scapula trapezius (upper fibres) and serratus anterior.

Question 20

describe the deltoid muscle.

Answer 20

• origin : anterior and upper at clavicle, acromion of scapula, spine of scapula.
• insertion : deltoid tuberosity on lateral humerus.
• nerve supply : axillary (C5, C6)

Question 21

what movements are the deltoid muscle a part of?

Answer 21

• anterior fibres : flex and medially rotate arm and shoulder.
• central and middle fibres : abduct arm from 15-90.
• posterior fibres : extend and laterally rotates arm at shoulder.

Question 22

describe the features of the trapezius muscles.

Answer 22

origin : external occipital protuberance of skull, nuchal ligament, spinous processes of C7, T12.
insertion : clavicle, acromion, spine of scapula.
nerve : spinal accessory nerve, proprioceptive fibres from C3 and C4.

Question 23

what movements are the trapezius muscle a part of?

Answer 23

• upper fibres : rotate acromion of scapula upwards during abduction of shoulder.
• lower fibres : rotate medial spine of scapula downwards.

Question 24

describe the features and movements of the serratus anterior.

Answer 24

origin : lateral ribs of 1-8 / 1-9.
*fibres pass deep into scapula and insert into medial border.
nerve : long thoracic nerve (C5,6,7) prone to injury at mastectomy causing winging of scapula.

actions : protraction of scapula, scapula rotation during shoulder abduction from 90-150.

Question 25

what muscles are responsible for extension of shoulder?

Answer 25

- posterior fibres of deltoid (axillary C5,6). - latissimus dorsi (thoracodorsal nerve C6,7,8). - teres major (lower subscapular nerve C5,6).

Question 26

describe the features of the latissumus dorsi.

Answer 26

- origin : spinous processes of T6-T12, thoracolumbar fascia, illiac crest and 3 lower ribs. - insertion : intertubucular sulcus of humerus. action : extends, adducts and medially rotates shoulder.

Question 27

describe the features of teres major.

Answer 27

- origin : posteriot surface of inferior scapula angle. - insertion : medial lip of intertubecular groove humerus. - action : adducts, extends and medially rotates the shoulder.

Question 28

what muscles are responsible for shoulder flexion.

Answer 28

- clavicular head of pectoralis major. : medial and lateral pectoral nerves. - anterior deltoid fibres : axillary. - carocabrachialis : musculocutaneos nerve. - biceps brachialis : musculacutaneous nerve.

Question 29

describe the features of pectoralis major.

Answer 29

- origin : clavicular head, sternocostal head. - insertion : lateral lip of intertubercular sulcus. - actions : adducts shoulder, flexes shoulder, internally rotates shoulder.

Question 30

describe the features of the caracobrachialis.

Answer 30

- origin : caracoid process of scapula. - insertion : medial humeral shaft. - nerve : musculocutaneous nerve. - action : weak flexor and adductor of shoulder.

Question 31

describe the features of biceps brachialis.

Answer 31

- origin : long head from supraglenoid tubercule of scapula and short head from caracoid process. - insertion : radial tuberosirty via biceps tendon and deep fascia of forearm. - actions : weak contribution to shoulder flexion, strong supinator, flexor of elbow.

Question 32

what muscles are responsible for shoulder adduction?

Answer 32

- pectoralis major. - latissimus dorsi. - teres major.

Question 33

what muscles are responsible for shoulder medial rotation?

Answer 33

- sternocostal head of pectoralis major, suscapularis, teres major, latissimus dorsi.

Question 34

what muscles are responsible for shoulder external rotation?

Answer 34

- infraspinatues : subscapular nerve. | - teres minor : axillary.