Shoulder Anatomy Flashcards Preview

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Flashcards in Shoulder Anatomy Deck (48)
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1
Q

what is in the shoulder complex?

A

clavicle
scapula
humerus

2
Q

why is stability sacrificed in the shoulder joint?

A

so it can have more mobility

3
Q

how many degrees of freedom does the shoulder joint have?

A

3

4
Q

what is on the end of the long bone?

A

articular cartilage

5
Q

what kind of CT is the fibrous capsule?

A

dense irregular

6
Q

what is the purpose of the joint capsule?

A

adds stability

lowers friction

7
Q

what gives the shoulder the greatest stability?

A

muscles

8
Q

what is dynamic stability?

A

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

9
Q

what is special about the scapulothoracic joint?

A

its not a true joint

a/w movement of the sc and ac joints

10
Q

what are the movements of the scapula?

A

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

11
Q

what forces hold the scapula to the thorax?

A

ATM
link with AC and SC jt
muscles

12
Q

what are functions of the scapula?

A

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

13
Q

what type of jt is the sternoclavicular jt?

A

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

14
Q

what are motions at the sternoclavicular jt?

A

elevation/depression
protraction/retraction
rotation

15
Q

how is the motion described for the sternoclavicular jt?

A

in terms of the distal portion of the clavicle

16
Q

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

A

ab/adduction

17
Q

which direction does sternoclavicular jt rotate?

A

posteriorly only!

18
Q

what kind of joint disc is in the sternoclavicular jt?

A

fibrocartilage

19
Q

which ligaments are involved at the SC joint?

A
anterior and posterior SC ligament
costoclavicular ligament (major constraint on SC motion)
interclavicular ligament
20
Q

what is the function of the SC joint?

A

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

21
Q

what is the sequence of brachial plexus?

A
roots
trunks
divisions
cords
nerves
22
Q

what levels are involved in the brachial plexus?

A

c5-t1

23
Q

which type of joint is the AC joint?

A

plane

24
Q

what is the primary function of the AC joint?

A

maintain relationship b/w clavicle and scapula

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

25
Q

what are the articulation surfaces in the AC joint?

A
  1. convex facet of lateral end of clavicle

2. concave facet on acromion of the scapula

26
Q

which ligaments are involved in the AC joint?

A
  1. superior and inferior AC ligaments
  2. coracoclavicular ligament
  3. coracoacromial ligament
27
Q

what are the motions of the AC joint?

A
  1. scapular rotation
  2. winging of the scapula
  3. tipping of the scapula
28
Q

what motion is altered in pathological winging?

A

flexion/abduction (scapula does not round around thorax)

29
Q

what motion is altered in pathological tipping?

A

elevation/depression (scapula does not round around thorax)

30
Q

what are the 2 parts of the coracoclavicular ligament?

A
  1. trapezoid
  2. conoid
    (separated by fat and a large bursa)
31
Q

which clavicular jt is more likely to get injured?

A

AC (sprains, subluxations, dislocations)

32
Q

what is the function of the AC joint?

A

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

33
Q

what is the position of the humeral head?

A

posterior torsion (retrotorsion)-30 degrees

34
Q

what is the angle of inclination of the humerus?

A

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

35
Q

what is the glenoid labrum?

A

dense, fibrous CT that provides excess depth to the socket

36
Q

when does the GH joint tighten?

A

during motion

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

37
Q

what are the GH ligaments?

A
superior/middle/inferior GH ligament (not as strong)-forms a Zshape
coracohumeral ligament (inserts on greater tubercle)
38
Q

what is the most important role of the coracohumeral ligament?

A

passive support against gravity

39
Q

what is the role of the coracoacromial arch?

A

protect bursa against trauma

prevents superior dislocation of the humeral head

40
Q

what are the joint motions of the shoulder jt?

A

roll, slide, spin

41
Q

which muscle supports for static stabilization?

A

supraspinatous muscle

if more force is needed, deltoid also contracts

42
Q

which are the primer movers for abduction?

A

deltoid

supraspinatous

43
Q

what is the primer movers for GH flexion?

A

anterior deltoid

44
Q

what is a major role of the rotator cuff?

A

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

45
Q

which two muscles are responsible for external rotation?

A

infraspinatous

teres minor

46
Q

which muscle is responsible for internal rotation?

A

subscapularis

47
Q

which muscle is responsible for humeral stability against gravity?

A

suprascapularis then deltoid

48
Q

which muscles cause the scapula to upwardly rotate?

A

trapezius and serratus anterior

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