Shoulder Anatomy

Question 1

what is in the shoulder complex?

Answer 1

clavicle
scapula
humerus

Question 2

why is stability sacrificed in the shoulder joint?

Answer 2

so it can have more mobility

Question 3

how many degrees of freedom does the shoulder joint have?

Answer 3

3

Question 4

what is on the end of the long bone?

Answer 4

articular cartilage

Question 5

what kind of CT is the fibrous capsule?

Answer 5

dense irregular

Question 6

what is the purpose of the joint capsule?

Answer 6

adds stability

lowers friction

Question 7

what gives the shoulder the greatest stability?

Answer 7

muscles

Question 8

what is dynamic stability?

Answer 8

when a joint is more dependent on muscles than other structures to give stability

Question 9

what is special about the scapulothoracic joint?

Answer 9

its not a true joint

a/w movement of the sc and ac joints

Question 10

what are the movements of the scapula?

Answer 10

elevation/depression
protration/retraction
upward/downward rotation (look at the inferior angle to identifty this motion)

Question 11

what forces hold the scapula to the thorax?

Answer 11

ATM
link with AC and SC jt
muscles

Question 12

what are functions of the scapula?

Answer 12

orient glenoid fossa to arm
add ROM to the arm
provide a stable base for the controlled rolling and sliding of the articular surface

Question 13

what type of jt is the sternoclavicular jt?

Answer 13

plane (saddle shaped surfaces)
has 3 degress of motion
incongruent

Question 14

what are motions at the sternoclavicular jt?

Answer 14

elevation/depression
protraction/retraction
rotation

Question 15

how is the motion described for the sternoclavicular jt?

Answer 15

in terms of the distal portion of the clavicle

Question 16

protraction/retraction of the sternoclavicular jt is a/w which movement of the scapula?

Answer 16

ab/adduction

Question 17

which direction does sternoclavicular jt rotate?

Answer 17

posteriorly only!

Question 18

what kind of joint disc is in the sternoclavicular jt?

Answer 18

fibrocartilage

Question 19

which ligaments are involved at the SC joint?

Answer 19

anterior and posterior SC ligament
costoclavicular ligament (major constraint on SC motion)
interclavicular ligament

Question 20

what is the function of the SC joint?

Answer 20

protects the brachial plexus and subclavian artery (pass between clavicle and 1st rib)

Question 21

what is the sequence of brachial plexus?

Answer 21

roots
trunks
divisions
cords
nerves

Question 22

what levels are involved in the brachial plexus?

Answer 22

c5-t1

Question 23

which type of joint is the AC joint?

Answer 23

plane

Question 24

what is the primary function of the AC joint?

Answer 24

maintain relationship b/w clavicle and scapula

allow scapula additional ROM on the thorax in latter stages of elevation

Question 25

what are the articulation surfaces in the AC joint?

Answer 25

1. convex facet of lateral end of clavicle | 2. concave facet on acromion of the scapula

Question 26

which ligaments are involved in the AC joint?

Answer 26

1. superior and inferior AC ligaments 2. coracoclavicular ligament 3. coracoacromial ligament

Question 27

what are the motions of the AC joint?

Answer 27

1. scapular rotation 2. winging of the scapula 3. tipping of the scapula

Question 28

what motion is altered in pathological winging?

Answer 28

flexion/abduction (scapula does not round around thorax)

Question 29

what motion is altered in pathological tipping?

Answer 29

elevation/depression (scapula does not round around thorax)

Question 30

what are the 2 parts of the coracoclavicular ligament?

Answer 30

1. trapezoid 2. conoid (separated by fat and a large bursa)

Question 31

which clavicular jt is more likely to get injured?

Answer 31

AC (sprains, subluxations, dislocations)

Question 32

what is the function of the AC joint?

Answer 32

prevent superior dislocation of the clavicle also provides horizontal stability also prevent excessive rotation of the scapula transmits compression forces to the stronger SC joint

Question 33

what is the position of the humeral head?

Answer 33

posterior torsion (retrotorsion)-30 degrees

Question 34

what is the angle of inclination of the humerus?

Answer 34

135 degrees (angle of direction of head compared to rest of the body)

Question 35

what is the glenoid labrum?

Answer 35

dense, fibrous CT that provides excess depth to the socket

Question 36

when does the GH joint tighten?

Answer 36

during motion | at rest, it is large and loose-2x the size of the humerus

Question 37

what are the GH ligaments?

Answer 37

``` superior/middle/inferior GH ligament (not as strong)-forms a Zshape coracohumeral ligament (inserts on greater tubercle) ```

Question 38

what is the most important role of the coracohumeral ligament?

Answer 38

passive support against gravity

Question 39

what is the role of the coracoacromial arch?

Answer 39

protect bursa against trauma | prevents superior dislocation of the humeral head

Question 40

what are the joint motions of the shoulder jt?

Answer 40

roll, slide, spin

Question 41

which muscle supports for static stabilization?

Answer 41

supraspinatous muscle | if more force is needed, deltoid also contracts

Question 42

which are the primer movers for abduction?

Answer 42

deltoid | supraspinatous

Question 43

what is the primer movers for GH flexion?

Answer 43

anterior deltoid

Question 44

what is a major role of the rotator cuff?

Answer 44

muscles produce inferiorly directed force which offsets the superior pull of the deltoid provide stability reduce forces of the humeral head moving in the glenoid fossa

Question 45

which two muscles are responsible for external rotation?

Answer 45

infraspinatous | teres minor

Question 46

which muscle is responsible for internal rotation?

Answer 46

subscapularis

Question 47

which muscle is responsible for humeral stability against gravity?

Answer 47

suprascapularis then deltoid

Question 48

which muscles cause the scapula to upwardly rotate?

Answer 48

trapezius and serratus anterior