Lecture 18: shoulder

Question 1

What is shoulder joint

Answer 1

Glenoid fossa with head of proximal humerus in it

Question 2

Describe proximal humerus lesser tubercle

Answer 2

Medial aspect rounded head

Question 3

Describe proximal humerus Inter tubercular groove

Answer 3

Attachment of muscle

Question 4

Describe proximal humerus Anatomical neck

Answer 4

Site of proximal growth plate of humerus - fused in adults
Remnants of where growth plate was where humerus develops

Question 5

Describe proximal humerus Surgical neck

Answer 5

Constriction distal to tubercles

Question 6

Describe proximal humerus Clinical correlate

Answer 6

Surgical neck - narrowing = weak spot, prone to fracture, especially in elderly or osteoporotic pppl

Question 7

Describe proximal humerus Greater tubercle

Answer 7

Larger
More lateral

Question 8

Describe proximal humerus Deltoid tubersoity

Answer 8

Rough, where deltoid muscle attaches

Question 9

what type of joint is glenohumeral

Answer 9

Ball and socket
Multi axial
In both directions in 3 planes, and combos of these

Question 10

Describe joint glenohumeral

Answer 10

Big ball =humeral head
But small, shallow socket = glenoid fossa, 3-4x smaller
= has functional consequences

Question 11

What motions at glenohumeral joint

Answer 11

Flexion extension = sagittal plane
Abduction adduction = coronal plane
Lateral rotation medial rotation = transverse plane (around longitudinal axis, bend elbow, flexion so then not using pronation/supination)

Question 12

Describe stability of shoulder

Answer 12

Multi axial large rom + shallow ill fitting ball and socket = INSTABILITY (more prone to dislocations and injuries)
So… glenohumeral joint reinforced by passive and active stabilization structures

Question 13

What passively stabilizes shoulder

Answer 13

Glenoid labrum
Ligaments

Question 14

Describe glenoid labrum

Answer 14

Lip - rim of fibrocartilage arounf edge of glenoid fossa and increases contact area = provides stability

Question 15

Describe ligaments that passively stabilize shoulder

Answer 15

Coracohumeral lig = sup aspect, joint to humeral head
Glenohumeral ligaments 3x
on back synovial capsule = no ligaments!!

Question 16

Describe shoulder dislocations - clinical correlate

Answer 16

Since posterior aspect joint capsule not reinforced by ligaments = posterior joint surfaces separate more easily —> 95% of shoulder dislocations are ANTERIOR with humeral head in subacromial position (ant and inf)
So head moves out towards easier

Question 17

What actively stabilizes shoulder

Answer 17

Rotator cuff muscles = 4 Muscles that attaches to scapula and run to tubercles of proximal humerus, all wrap arounf shoulder joint capsule - pull joint closer together when contract
Provides shoulder mobility and active stability (by pulling humeral head against genloid fossa)

Question 18

Name the rotator cuff muscles

Answer 18

SItS muscles =
Supraspinatus, infraspinatus, Teres minor, subscapularis

Question 19

Describe what is between Teres minor and subscapularis

Answer 19

Recess of synovial membrane = extra fold so can have extra rom of shoulder
Present in joint, like fibrous capsule area

Question 20

Supraspinatus attachments

Answer 20

Suprapsinous fossa to superior facet greater tubercle

Question 21

Supraspinatus Function

Answer 21

Abduction = especially early, first 30 degrees of abduction

Question 22

Supraspinatus Innervation

Answer 22

Supra scapular nerve c5-c6

Question 23

Supraspinatus = describe where it runs specifically

Answer 23

Runs over top of glenohumeral joint in narrow subacromial space, inf to acromion and coracohumeral ligament, space also contains a subacromial bursa
Stuck between humeral head and roof, between tendon and muscle of Supraspinatus roof

Question 24

Supraspinatus Clinical correlate

Answer 24

Narrow subacromial space makes Supraspinatus tendon prone to inflammation due to friction = can lead to rotator cuff tendinitis
Supraspinatus tendon involvement can be diagnosed by painful arc test = where pain due to ss tendon impingement can be felt between 60-120 degrees abduction

Question 25

What is scapulohumeral rhythm

Answer 25

Collaborative movements of scapulothoracic and glenohumeral joints = increase rom in shoulder abduction

Question 26

What is scapulohumeral rhythm = what contributes to it

Answer 26

Each joint contributes to total abduction range Glenohumeral = 120 degrees Scapulothoracic (acc sternoclavicular)= 60 degrees for a total of 180 degrees

Question 27

Describe first 30 degrees abduction of shoulder

Answer 27

Movement happens at glenohumeral joint, mainly Supraspinatus

Question 28

Describe >30 degrees abduction of shoulder

Answer 28

Involves concurrent movements at sternoclavicular (trapezius, Serratus anterior in upwards rotation) AND gelnohumeral joints (lateral deltoid and Supraspinatus)

Question 29

Infraspinatus attachments

Answer 29

Infraspinous border to middle facet greater tubercle

Question 30

Infraspinatus Functions

Answer 30

Lateral rotation (external)

Question 31

Infraspinatus Innervation

Answer 31

Supra scapular nerve c5-6

Question 32

Teres minor attachment

Answer 32

Inferior border scapula to inferior facet greater tubercle

Question 33

Teres minor Function

Answer 33

Adduction = weak Lateral rotation

Question 34

Teres minor Innervation

Answer 34

Axiallary nerve - c5-c6

Question 35

Subscapularis attachments

Answer 35

Subscapular fossa to lesser tubercle humerus (Mirror of Teres minor and infraspinatus = reverse motions)

Question 36

Subscapularis Function

Answer 36

Medial rotation Weak adduction (Swimming stroke)

Question 37

Subscapularis Innervation

Answer 37

Superior and inferior subscapular nerves c5-c6

Question 38

Name shoulder muscles

Answer 38

Deltoid Teres major

Question 39

Deltoid attachments

Answer 39

Triangular shaped Spinal part = posterior scapula Acromial part = lateral acromion Clavicular part = anterior clavicle Scapula and clavicle —> deltoid tuberosity

Question 40

Deltoid Function

Answer 40

Clavicular - anterior = flexion Acromial - Lateral = abduction Spinal - posterior = extension from flexed position - bring it back

Question 41

Deltoid Innervation

Answer 41

Axilalry nerve - c5-c6

Question 42

Deltoid Clinical correlate

Answer 42

Subdeltoid bursa connected to subacromial bursa, between Supraspinatus tendon (deep) and deltoid muscle (superficial) Bursae are prone to inflammation and swelling = bursitis, further narrowing subacromial space and contributing to Supraspinatus impingement in rotator cuff tendinitis

Question 43

Teres major attachment

Answer 43

Inferior angle scapula (posterior) to crest of lesser tubercle of humerus (anterior) Back to front muscle, so on other side fo longitudinal axis rotation —>has opposite action to Teres minor

Question 44

Teres major FUCNTION

Answer 44

Adduction Medial rotation Extension when shoulder flexed

Question 45

Teres major INNervation

Answer 45

Lower subscapular nerve c5-c6

Question 46

Name thoracohumeral muscles

Answer 46

Thorax muscles with shoulder actions = latissimus dorsi and Pectoralis major Thoracoappendicular muscles

Question 47

Attachments latissimus dorsi

Answer 47

Vertebrae, ilium and tlf to floor of intertubercuar groove of humerus Back to front muscle like Teres major

Question 48

fucntion latissimus dorsi

Answer 48

Crosses both scapulothoracic and shoulder joints = adduction (strong adductor of shoulder joint), medial rotation

Question 49

innervation latissimus dorsi

Answer 49

Thoracodorsal nerve c6-c8

Question 50

Attachments Pectoralis major

Answer 50

From clavicle, sternum and ribs (3 parts) to crest of greater tubercle of humerus - all converge

Question 51

Pectoralis major FUCNTION

Answer 51

Medial rotation Adduction

Question 52

Pectoralis major Innervation

Answer 52

Medial pectoral nerve c8-t1 Lateral pectoral nerve c5-c7

Question 53

How to get pure adduction of shoulder

Answer 53

Latissimus, Teres major and Pectoralis major all do medial rotation Teres minor and infraspinatus need to counteract bc do lateral rotation =recruit all to get pure adduction

Question 54

Describe attachment of certain muscles to proximal humerus

Answer 54

Pectoral major = lateral/greater crest Latissimus dorsi = floor interbercular groove Teres major = crest of lesser tubercle “Miss between 2 majors” (All on anterior side)

Question 55

Define bursa

Answer 55

Thin fluid filled sac that reduces friction between muscle and surrounding structures