shoulder Flashcards
What is the main function of the shoulder
to position and stabilize the arm in space
the 4 anatomic articulations of the shoulder
1) Glenohumeral joint
2) sternoclavicular joint
3) acrominoclavicular joint
4) scapular thoracic joint
the 6 biomechanics articulations of the shoulder
1) Glenohumeral joint
2) sternoclavicular joint
3) acrominoclavicular joint
4) scapular thoracic joint
5) coraco-aromial arch
6) upper thoracic spine
motion of the shoulder
flexion/extension
abduction/adduction
internal/external rotation
horizontal abduction/adduction
the GH joint
is a ball and socket joint but is much more shallow (more mobile less stable)
structural stability of the GH
is minimal
has the glenoid labrum that slightly deepens,muscle tendons, ligaments
ligamentous support of the GH
not very many
anterior and posterior GH ligaments
muscular support of the GH
rotator cuff is critical. need to maintain integrity, strength, and motor control and head of the bicepts
arthrokinematics at the GH joint
convex humerus moving on a concave glenoid cavity.
roll and side occur in opposite directions. Inferior glide needs to occur with elevation.
scapular mobility
medial and lateral translation at the acromioclavicular joint allows for upward and downward rotation of the scapula. need scapular movement with shoulder flexion and abduction
scapular thoracic cardial planes
retraction
protraction
elevation
depression
upward and downward rotation
(all are component motions of physiologic shoulder mobility and all can be created passively with our with GH joint motion)
only retraction, protraction, elevation, and depression can occur actively in isolation
scapulohumoral rhythm
combined and integrated motion must occur across the 4 anatomic joints
(1/3) of elevation comes from scapulothoracic joint and 2/3 from GH
Active shoulder mobility functions (codman’s paradox)
is the idea that when there is shoulder abduction greater then 30 degrees there has to be component external roation at the GH
shoulder flexion need:
120-GH
60-scap
shoulder abduction needs:
125 -GH
55- Scap
also need external rotation
elevation and depression of the clavicle axis
occur on the anterior and posterior axis
protraction and retraction of the clavicle
occur on the vertical axis
rotation of the clavical
occur on the medial to lateral axis
behind the back (low) scratch test
extension and internal rotation
behind the back (high) scratch test
flexion and external rotation
the superior anterior GH ligament
gets tense with arm at side
the middle anterior GH ligament
gets tense with 45 degrees of abduction
the inferior anterior GH ligament
gets tense with abduction above 90 degrees
what position of the humerus is necessary to asses joint play for anterior glide hypermobility?
90 degrees of abduction
90 degrees of external rotation
90 degrees of flexion
(the apprehension test)
what ligaments must tear if there is a dislocation of the acromioclavicular joint
The AC ligament and the coracoclavicular ligaments (conoid and trapezoid)
what are the 4 functional muscle groups at the shoulder
cuff protectors and stabilizers
scapular positioners
GH powers
Upper extremity Propellers
the cuff protectors and stabilizers
rotator cuff (SITS) and long head of the biceps
scapular positioners
traps (upper, med, and low) Rhomboids,pect minor, seratus anterior
GH propellers
deltoid, pect major, and Lats
the subacrominal/coraco-acromial arch
the area between the coracoid process to the acromion process: underneath the coracoacromial ligament
what passes under the coraco-acromial arch/ subacromial arch
sub deltoid bursa
rotator cuff and long head of the biceps
boney aspects of the head of the humerus
subacromial impingement
can be caused by bursa, swollen tendon, thick ligament, or hooked clavicle
as the arm raises the ball slides down. an impingement stops the space at the top of the joint closing up and keeps good contact between the joint surfaces
neuro bundle impingements (sensitive spot)
anterior and medial scaleless
subclavian to the 1st rib
pac minor creates space for the brachial plexus
dislocation of the GH anteriorly
superior, middle, and inferior GH ligmants
dislocation of the sternoclavicular
anterior and posterior sternoclavicular ligaments, interclavicular ligament, costeoclavicular ligament
function of the posterior delt
extension and external rotation
at 90 degrees it can do horizontal abduction
function of the anterior delt
flexion with internal rotation
function of the middle delt
abduction
force couples at the scapulothoracic joint
2 or more muscles at opposing sides of a joint working together to provide rotation and stability
example: upper trap, lower trap, and serratus anterior work together to rotate the scapula up
force couples across the GH joint
muscles that have to work together to get proper function at the shoulder
ex: suprapinatus and anterior delt in shoulder flexion
zones of avascularity
cartilage, bone (heals well unless it is fractured at sight of blood vessels), cruciate ligaments and meniscu, labrum at the hip, glenoid labrum (SLAP tear might occur where the biceps tendon anchors to the labrum)
avascularity at the supraspinatus tendon
worse with arm at the side because with out stretching the tendon the blood supply is not able to flow through
avascularity with adhesive capsulitis
immobility, trauma or idiopathic inflammation of the joint capsule leads to fibrous adhesions to form
biomechanical rehab goal with upper cross syndrome
open the subacromial space
stretch the anterior muscles (pect.)
Strengthen the scapular positioners
improve upper thoracic mobility into extension
