Shoulder Complex

Question 0

Shoulder mobility and stability

Answer 0

Dynamic stabilization : moving segment is limited by decreased passive forces

Question 1

Shoulder joint consists of :

Answer 1

Clavicle
Scapula
Humerus
GHJ, SCJ, ACJ, STJ

Question 2

Components of shoulder joint complex :

Answer 2

Sternoclavicular joint
Acromioclavicular joint
Glenohumeral joint
Scapulothoracic joint

Question 3

SCJ

Answer 3

Plane synovial ( during motion: acts as hinge/ pivot joint 
3 dof :( elevation , depression, protraction, retraction,anterior and posterior rotation of clavicle )
Joint capsule 
Joint Disc 
3 major ligaments

Question 4

SCJ motion:

Answer 4

Elevation/ depression: Roll and slide with upper attachment as pivot point.
Protraction/ retraction: roll and slide with downward attachment as pivot joint

Question 5

SCJ disc

Answer 5

Fibrocartilagenous
Increase congruence between articualting surfaces
Limits the medial movement of clavicle

Question 6

Components of SCJ:

Answer 6

Lateral: b/w disc and clavicle - elevation and depression
Medial: b/w disc and manubrium - protraction/ retraction
Costoclavicular: anterior and posterior rotation - long axis of rotation

Question 7

SCJ capsule

Answer 7

Strong fibrous

3 ligaments : anterior and posterior SC ligaments , bilaminar costoclavicular ligament, interclavicular ligament

Question 8

Ante/ post SC ligament

Answer 8

Reinforce capsule

Checks translatory movement of medial end of clavicle

Question 9

Bilaminar costoclavicular ligament

Answer 9

Limits elevation at lateral end of clavicle

Permits inferior glide of medial clavicle when taut

Question 10

Intercalvicular ligament

Answer 10

Limit increased depression of distal clavicle

Permits superior glide of medial clavicle on manubrium

Question 11

Elevation/ depression at SCJ joint :

Answer 11

Moves around AP axis
B/w convex clavicle and concave manubrium
Inferior slides occurs opposite to the movement of clavicle
E-lateral clavicle rotates up and slides down
D- lateral clavicle rotates down and slides up
Elevation- 48 degrees
Depression- <15 degrees

Question 12

Protraction and retraction at SCJ joint.

Answer 12

Occurs around vertical axis
P- lateral clavicle moves anterior, medial clavicle slides anterior
R- lateral clavicle moves posterior, medial clavicle slides posterior
Concave on convex ( clavicle on manubrium)
15-20 degrees protraction
>30 degrees retraction

Question 13

Anterior and posterior rotation of clavicle

Answer 13

Spin during rotation of clavicle
Clavicle rotates posterior from neutral ( inferior clavicle faces anterior)
Anterior rotation - <10 degrees
Posterior rotation - 50 degrees

Question 14

SCJ stress

Answer 14

SCJ is incongruent
No degree of degenerative changes
SC disc and costoclavicular ligament decreases articular stress
Decrease in intraarticular motion and therefore dislocation or subluxation occurs.

Question 15

ACJ

Answer 15

Acromion process of the clavicle and clavicle
Incongruent articular surfaces
Joint disc - union of fibrous cartilage and it’s size vary by an individual
Capsule - weak and decreases integrity of the joint without reinforcement of superior or inferior Acromioclavicular ligament and corococlavicular ligament. These ligaments assist capsule in apposing articular surfaces

Question 16

ACJ ligaments

Answer 16

Superior Acromioclavicular ligament
Inferior Acromioclavicular ligament
Corococlavicular ligament

Question 17

Superior ACL

Answer 17

Main one
Limits movement by anterior force on distal clavicle
Trapezius and deltoid fibers reinforce this ligament therefore stronger superior joint support than inferior

Question 18

Corococlavicular ligament

Answer 18

Do not directly belong to ACL
Firmly Unites clavicle and scapula
Provides superior and inferior joint stability
Divided into: medial portion- conoid ligament , lateral portion- trapezoid ligament

Question 19

Conoid ligament

Answer 19

Medial and slightly posterior to the trapezoid
Triangular and vertically oriented
Provides restraint to translatory motion by superior directed force to distal clavicle.

Question 20

Trapezoid ligament

Answer 20

Quadrilateral shaped
horizontally oriented
Provide restraint to translatory motion caused by posterior directed force to distal clavicle .

Question 21

Motions of ACJ

Answer 21

Internal rotation / external rotation
Anterior/ posterior tilting occurs in an oblique”coronal axis”, anterior tilting causes acromion tilt forward and inferior angle tilting backward. Posterior tilting rotates acromion backward and inferior angle tilting forward.
Upward / downward rotation

Question 22

IR / ER at ACJ JOINT:

Answer 22

occurs around vertical axis.
glenoid fossa of the scapula runs anteromedially and posterlaterally
aims glenoid fossa toward the plane of of humeral elevation.

Question 23

ANTERIOR /POSTERIOR TILTING AT ACJ JOINT:

Answer 23

occurs in an oblique”coronal axis”

• anterior tilting causes acromion tilt forward and inferior angle tilting backward.
• Posterior tilting rotates acromion backward and inferior angle tilting forward.
• elevation of scapula on the thorax or shoulder shrug results in anterior tilting
• flexion or abduction of arm results in scapula posterior tilt as scapula is upwardly rotated.
• passive ant/post tilting ROM is 60 degrees in cadavers

Question 24

UPWARD/DOWNWARD ROTATION AT ACJ JOINT:

Answer 24

occurs around AP axis perpendicular to the plane of scapula.
UR tilts glenoid fossa upward, and DR tilts glenoid fossa downward
for UR coracoid process and superior border of scapula runs inferiorly away from the clavicle.

Question 25

ACROMIOCLAVICUALR STRESS:

Answer 25

Susceptible to both trauma and degenerative changes.