week1 SEM 2 Joints of the Shoulder Region Flashcards
shoulder joint complex consists of 4 different joints
- Glenohumeral joint
- Acromioclavicular joint
- Sternoclavicular joint
- Scapulothoracic joint
Glenohumeral (shoulder) joint classification and movements
*Classification
synovial, multiaxial, ball and socket
*Movements
* flexion - extension
* abduction – adduction
* internal (medial) -external (lateral)
what makes the glenohumeral joint
humeral head ~1/2 sphere
glenoid fossa - very shallow
only 25 - 30% contact between articular surfaces
what is the attachment of the glenohumeral joint
- medially to margin of glenoid fossa and glenoid labrum
- laterally to margin of anatomical neck of humerus
- reflected inferiorly onto medial shaft of humerus
the glenohumeral joint is reinforced by
- rotator cuff tendons
- long head of triceps tendon
- glenohumeral and coracohumeral ligaments (capsular ligaments)
Glenoid labrum
function and what it is
- fibrocartilaginous structure
around glenoid fossa - functions to:
- facilitate mobility
- increase glenoid concavity- up to
50% - provide attachment for joint
capsule, ligaments, muscles
what is the orientation of the glenoid fossa
When the arm is hanging the glenoid fossa faces:
* laterally
* slightly anteriorly
* slightly superiorly
glenohumeral ligament superior middle and inferior ( prevent and limit)
- from anterior glenoid rim to humerus
-superior - prevents lateral and therefore, inferior
dislocation of the humerus - limits external rotation
- middle
- limits external rotation
- inferior
- prevents anterior dislocation of humerus
when fully flexed/abducted
Transverse humeral ligament
- passes between the humeral
tubercles - holds long head of biceps brachii
in the bicipital groove
Coracoacromial
- from coracoid to acromion
- prevents superior dislocation of
humerus
Acromioclavicular joint classification
synovial, multiaxial, plane
Acromioclavicular joint articular surface and capsule
-Articular surfaces
* acromial end of clavicle
* anterior, medial acromion
-Articular capsule
* loose
* reinforced by capsular ligaments
* intra-articular disc
* partial disc which functions as a shock absorber
Coracoclavicular (from coracoid to
clavicle) ligament
- conoid part (attaches to conoid tubercle)
- vertical
- limits protraction of scapula
- produces axial rotation of clavicle
- trapezoid part (attaches to trapezoid line)
- oblique
- limits retraction of scapula
- prevents medial dislocation of scapula
Sternoclavicular joint classification
synovial, multiaxial, plane
Sternoclavicular joint articular surface and capsule
-Articular surfaces
* sternal end of clavicle (male)
* clavicular notch of sternum (female)
* costal cartilage of rib 1
-Articular capsule
* strong
* reinforced by capsular ligaments
Sternoclavicular joint intra-articular disc
- vertical disc dividing joint cavity into medial and lateral
compartments - functions:
- shock absorber
- prevents superior dislocation of clavicle
- thrusting forces
- weight in hand
Sternoclavicular joint- Costoclavicular ligament (from rib 1 to clavicle)
- bilaminar (two layers), running at 90 degrees to one another
- limits elevation of clavicle
- limits protraction and retraction
- acts as a fulcrum or pivot about which movements occur
Sternoclavicular joint- Anterior sternoclavicular (from sternum to clavicle)
- limits retraction
Sternoclavicular joint- posterior sternoclavicular (from sternum to clavicle)
- limits protraction
Sternoclavicular joint- Interclavicular
between clavicles
Scapulothoracic joint function
- allows scapular motion against the rib cage
what are rorator cuff muscles
they provide dynamic stability at sgoulder joint by:
take up slack in shoiulder joint capsule during movment
provide medial force to the humeral head
provide medial force
scapulohumeral rhythem
increases range of motion - head rolls and glides on a moving glenoid fossa which moves by moving the scapula
maintains muscles at optimal length for effective contraction (deltoid and rotator cuff muscles)
