Shoulder Complex Overview/Pathology/Stabilizers Flashcards
What are the joints that make up the shoulder complex?
sternoclavicular
acromioclavicular
glenohumeral
scapulothoracic
What is the one joint in the shoulder girdle that is not a true synovial joint?
scapulothoracic
SC joint
articulation between : Sternal end of clavicle, clavicular notch of sternum, superior surface of first costal cartilage; intra-articular fibrocartilaginous disc
type: saddle joint
motion: gliding and rotation motion
the articular disc divides the joint in two; increases the surface area of the joint, and increases shock absorption
SC joint convex and concave joint surfaces:
clavicle:
superior-inferior: convex
anterior posterior- concave
manubrium
superior-inferior: concave
anterior-posterior- convex
protraction:
-anterior roll and glide of the concave clavicle on the manubrium
retraction: posterior roll and glide of the clavicle
elevation: superior roll and inferior glide of the convex clavicle on concave manubrium
depression: inferior roll and superior glide of convex clavicle on concave manubirum
ligaments of the SC joint:
SC ligament - anterior and posterior; dense thickening of the capsule
costoclavicular ligament - taught with elevation and retraction
interclavicular ligament integrates into the fascia of the neck
What muscle stabilizes the SC joint?
subclavius muscle
SC joint dislocation:
-can happen ant or posterior
-very rare
-direct trauma or blow to the clavicle or with fall on an outstretched arm
-MUCH more common to fracture the clavicle
-anterior dislocation usually does well non-surgically
-posterior dislocation–> more risk to structures behind sternum
-surgery (autograft or allograft) may be indicated- semitendinosus tendon
AC joint characteristics
type: plane/gliding joint
articulation: Acromion of scapula, acromial end of clavicle
motions: gliding in all directions
ligaments:
-AC lig
-coracoclavicular ligament:
—trapezoid (more lateral)
—conoid (more medial, deeper)
with abduction-adduction of shoulder girdle- rotation of acromion on clavicle
AC joint sprain (separated shoulder)
-progressive disruption of ligaments
—AC lig
—coracoclavicular ligaments
-graded by degree of displacement
-grades 1-3 can be managed non-surgically
GRADE 1 - not torn AC lig just sprain, no medial lig damage
GRADE 2- AC torn, stretched medial ligs
GRADE 3- complete luxation of the joint due to tearing of all the ligaments
GRADE 4- clavicle is severely displaced posteriorly
GRADE 5 - clavicle is severely displaced superiorly
GRADE 6- clavicle is displaced under the coracoid process
Scapulothoracic joint characteristics
“pseudo” joint
-muscular joint between the scapula and the thoracic cage
-required for full ROM at the GH joint
-no direct ligament attachment
MOVEMENTS:
-abduction (protraction)
-adduction (retraction)
-upward rotations, downward rotation , IR, ER, anterior and posterior tilt
-depression and elevation
rotations are fully reliant on muscular control
Scapular positioning/scapulohumeral rhythm:
The glenoid moves like a seal’s nose to remain in the right spot to control the ball (head)– > congruency is very important
SCAPULOHUMERAL RHYTHM (movement coordination) function:
-allows for greater overall shoulder ROM
-maintains optimal contact between the humeral head and the glenoid fossa
-Assists with maintaining an optimal length-tension relationship of the glenohumeral muscles.
Characteristics SH Rhythm
-integrated movements of GH, ST, AC, AND SC JOINTS
-sequential fashion –> full motion of shoulder complex
ARM ELEVATION EVIDENCE:
-more elevation on non-dom side (more upward rotation)
-between 1:3 AND 1:5 scapula to humerus motion –> depends on plane of humeral motion, side of dominance, and age of patient
-movement patterns depend on if you’re moving unilaterally or bilaterally
How is the thoracic spine involved in scapulohumeral rhythm?
Bilateral shoulder motion: 10-30 degrees of thoracic extension
(primarily lower) with full shoulder elevation
- Unilateral shoulder motion:10-30 degrees of thoracic rotation
and/or side-bending - Clinical relevance: Assess thoracic motion in patients with shoulder symptoms!
Glenohumeral joint characteristics
shoulder joint
synovial
multiaxial
ball and socket
largest ROM and movement in the body
-shallow joint
-extensive joint capsule
-limited ligamentous support
Static stabilizers of the GH joint:
LABRUM
-the fossa is 1/4 the size of the humeral head
-fossa is pear-shaped–> reducing congruency
-the labrum helps increase concavity of the glenoid fossa as well as the articular cartilage (but to a lesser extent)
-fossa is smaller on the superior aspect than inferior
-the labrum deepens the socket 50-75%
-Glenoid faces lateral, anterior, and superior
–> angle of inclination changes with the position of the scapula (scapulohumeral rhythm)
JOINT CAPSULE
-tissue: anterior and
posterior continues laterally on
the humerus into the neck of the humerus
-anterior and inferior capsule much thicker than posterior
LIGAMENT COMPLEX
-SGHL
-MGHL
-IGHL
Dynamic stabilizers of the GH joint:
muscles surrounding the joint
ROTATOR CUFF - pulls head of humerus into glenoid fossa
-supraspinatus
-infraspinatus
-subscapularis
-teres minor
** Long head of the biceps (not technically)
-tendons intimate with capsule
-tendinitis is rarely isolated to one tendon –> muscles and tendons DO NOT function in isolation
DELTOID
-large stabilizing component, regardless of humeral position
-** primary function to swing humerus
