shoulder complex - joitns

Question 1

Sternoclavicular joint (SCJ) location

Answer 1

Between:
• the clavicle and
• the sternum & 1st costal cartilage
(disparity in joint surfaces)
* synovial saddle - biaxial

Question 2

Passive structures that enhance stability of SCJ

Answer 2

Ligaments:
• Anterior
• Posterior
• Interclavicular • Costoclavicular
Meniscus / intra-articular disc

Question 3

SCJ need for stability?

Answer 3

lots of ligament reinforcements

due to number of neurovascular structures within area

Question 4

Movements of the clavicle & sternoclavicular joint (SCJ):

Answer 4

Synovial saddle joint
Biaxial diarthrosis
1. Elevation – depression
2. Protraction - retraction
Conjunct rotation!

Question 5

Acromioclavicular joint (ACJ) location

Answer 5

•Between:
distal end of clavicle &
•acromion process of the scapula

Question 6

ACJ

Answer 6

Synovial plane joint
gliding + rotation
uniaxial

Question 7

Passive structures that enhance stability of the ACJ:

Answer 7

Superior & inferior ACJ ligaments

• Coracoclavicular ligaments = conoid ligament + trapezoid ligament

Question 8

conoid ligament

Answer 8

Coracoclavicular ligaments - vertical
suspends scapula &
• resists superior glide of lateral clavicle

Question 9

trapezoid ligament

Answer 9

Coracoclavicular ligaments - superolateral
Resists medial glide of the scapula relative to the clavicle
helps prevent medial displacement of the acromion process under the clavicle during a medial force to the shoulder
• assists transfer of force to axial skeleton

Question 10

conoid

Answer 10

Conoid ligament links movement of the scapula & clavicle
• Coracoid process
• Conoid tubercle (inferior & posterior point of the lateral convex curve of clavicle)

Question 11

conoid lig. upper arm abduction

Answer 11

Abduct upper limb
> upward rotation of scapula
> tightens conoid ligament
> pulls conoid tubercle inferiorly = upward rotation of the clavicle!

Question 12

Glenohumeral Joint GHJ

Answer 12

MOBILITY at expense of stability!
– multiaxialdiarthrosis
– Synovialball&socketjoint
• Flexion – extension
• Abduction – adduction
• Horizontal flexion - extension • Medial & lateral rotation
• Circumduction

Question 13

GHJ plane

Answer 13

Scapular plane 30-45˚ anterior to coronal plane/from frontal plane … glenoid faces anteriorly
scap affected by shape of thoracic cage

Question 14

GLENOHUMERAL JOINT BONY STABILITY:

Answer 14

Similar radius of curvature in both surfaces
- good congruency
•Disparity in size of articular surfaces
- minimises bony limitation to movement
- provides little bony stability
* Stability heavily reliant on non bony structures
- Labrum
- Capsulo-ligamentous
- Muscles

Question 15

ligament vs muscle support

Answer 15

muscles provide support through range

ligaments provide support at end of range

Question 16

GLENOID LABRUM

Answer 16

• Fibrocartilage rim attached to the margin of the glenoid fossa
• approximately doubles the depth of the glenoid fossa
• Increases the articular contact area
• Deformable = less restriction to GHJ movement
• Superior labrum (along with the supraglenoid tubercle) provides attachment for long biceps tendon (LBT)

Question 17

Glenohumeral joint capsulo-ligamentous complex:

Answer 17

• Resists excessive rotations & translations

* From glenoid margin / labrum to anatomical neck of humerus

Question 18

GHJCLC - Anterior Capsular ligaments:

Answer 18

Resist anterior–inferior displacement of the HOH
Taut in different ranges of GHJ ABD / ER
1. Coracohumeral ligament* (CHL)
2. Superior glenohumeral ligament (SGHL)
3. Middle glenohumeral ligament (MGHL)
4. Inferior glenohumeral ligament complex (IGHLC): anterior band posterior band axillary pouch

Question 19

GHJCLC - Posterior Capsular ligaments:

Answer 19

does not have capsular ligame

Question 20

Subacromial space & bursae:

Answer 20

subacromial (subdeltoid) bursa Separate from GH joint

• subcoracoid (subscapular) bursa continuous with joint

Question 21

bursa

Answer 21

synovial sacs that lubricate and minimise friction

Question 22

ligament summary (9)

Answer 22

1. Costoclavicular ligament
2. Coracoclavicular = Conoid ligament + Trapezoid ligament
3. Coracoacromial ligament
4. Transverse scapular ligament
5. Coracohumeral ligament
6. Superior glenohumeral ligament
7. Middle glenohumeral ligament
8. Inferior glenohumeral ligament complex – anterior & posterior bands
9. Transverse humeral ligament

Question 23

Magnitude of contribution to shoulder complex ROM:

Answer 23

GHJ > > SCJ > ACJ

Question 24

Scapulothoracic “joint”

Answer 24

NOT a true anatomical joint!
“Functional joint” between the scapula and the thoracic wall
Scapulothoracic motion indicates sternoclavicular & acromioclavicular motion

Question 25

What is the relative contribution of the 3 anatomical joints of the shoulder region to full (~180o) UL abduction?

Answer 25

GHJ > SCJ > ACJ

Question 26

scapulohumeral rhythm

Answer 26

rhythmic; coordinated; symmetrical (all in time)
GHJ:SCJ = 2: 1
rhythimical, coordinated movement of the scapula up. rotation and GHJ flex /abd during upper limb elevation.