Shoulder- Part 1- Kinematics Flashcards
The arthrology components of the shoulder
Acromioclavicular (AC)- functional and anatomical
Sternoclavicular (SC)- functional and anatomical
Scapularthoracic (ST)- functional
Glenoidhumeral- functional and anatomical
Osteokinematic motions of ST joint
Elevation/depression
Retraction/protraction
Upward rotation/ downward rotation
SC joint, which done is moving?
Clavicle- not sternum
SC- osteokinematics, degrees of freedom, and planes for each motion
3 degrees of freedom
elevation/depression- frontal plane
protraction/retraction- horizontal plane
anterior/posterior rotation- sagittal plane
SC- Location and direction of axis for each motion
- Elevation/depression: anterior/posterior on the convex part of sternum
- Protraction/retraction: vertical axis on the convex part of sternum
- Anterior/posterior rotation: medial/later axis located along the clavicle
SC- arthrokinematics of each osteokinematic motion
- Elevation/depression: convex-on concave, roll and slide opposite
- Protraction/retraction: concave-on-convex, roll and slide same
- Anterior/posterior rotation: spin
AC joint, which bone is moving?
Scapula
AC- Osteokinematics, degrees of freedom, and planes for each motion
3 degrees of freedom
Upward/downward rotation: frontal plane
Internal/external rotation: horizontal plane
Anterior/posterior tilting: sagittal plane
AC- Location and direction of axis for each motion
-Upward/downward rotation: A/P
-Internal/external rotation: vertical
-Anterior/posterior tilting: M/L
Location of axis isn’t important because it is different on everyone
Primary function of AC joint in regards to ST joint?
Allow scapula to move in 3 dimensions and increases upper extremity motion. Allows scapula to remain congruent with humerus and permits it to maintain a stable base
Shoulder shrug
Shoulder protraction
Shoulder abduction
SC elevation and AC downward rotation
SC protraction and AC internal rotation
ST elevation, SC elevation, and AC upward rotation
Ultimate function of scapular motion
- Orient the glenoid for optimum contact for humeral head. 2. Add ROM to elevation of arm (hand over head, nonspecific). 3. Provide stable base for humerus.
Neutral position for glenoid fossa
Mostly lateral, slightly anterior and slightly superior. In some cases
Neutral position for humeral head
Not just opposite.
Medially, slightly superior and a little posterior
Components of static stabilization of GHJ
Coracohumeral ligament, supraspinatus, superior capsule. Also, negative pressure.
GHJ- osteokinematic motions, degrees of freedom, and plans of motion
3 degrees of freedom.
Flexion/Extension- Sagittal
Abduction/Adduction- Frontal
Internal/External Rotation- Horizontal
GHJ- direction and location of axis for each motion
Flexion/extension- M/L
Abduction/Adduction- A/P
Internal/External Rotation- Vertical
All through the center of the humeral head
GHJ- arthrokinematics of each osteokinematic motion
Flexion/extension- Convex-on-concave: opposite
Abduction/Adduction- Convex-on-concave: opposite
Internal/External Rotation- Convex-on-concave: spin
What happens to humeral head during arm elevation?
The humeral head goes slightly up and surface of joint goes down, meaning there is a little more role than slide
Total ROM at shoulder with abduction and flexion?
180 degrees
Ratio of GH to ST joint motion?
GH= 120 degrees ST= 60 degrees
Scapular humeral rhythm
quarantined movement of scapula and humerus at the same time
Joint motions for early phase, 90 degrees of flexion/abduction
- 60 degrees from GHJ
- 30 degrees from ST joint: primarly AC upward rotation, little from SC elevation
Joint motion for late phase, 90 degrees for flexion/abduction
- 60 degrees from GHJ
- 30 degrees from ST joint: little from AC upward rotation, primarily SC elevation
6 kinematic principles during shoulder abduction
- Scapulohumeral rhythm 2:1 for total 180 degrees. 120 from GHJ and 60 from ST joint
- 60 degrees from scapular upward rotation from combined SC and AC joint motion
- Clavicle retracts at SC joint
- Scapula posteriorly tilts and externally rotates
- Clavicle posteriorly rotates (late phase)
- GHJ externally rotates
