Boney landmarks of the shoulder region
Clavicle: Spine Acromion process Coracoid process Glenoid fossa
Humerus: Head Neck Greater tubercule Lesser tubercle Intertubercular groove
Joints of the shoulder girdle
1. Sternoclavicular joint
Articulating bones
-sternum
-clavicle
Type of joint: Saddle
2. Acromioclavicular joint
Articulating bones
-scapula
-clavicle
Type of joint: gliding
3. Scapulothoracic joint
Articulating bones
-scapula
-thorax
Type of joint
-not a true jointMovements of the shoulder girdle
SCAPULAR:
Elevation-depression
Abduction-adduction
Upward rotation-downward rotation
Shoulder joint structure
Technical name: glenohumeral joint
Articulating bones: humerus, scapula
Articulating landmarks: head of humerus, glenoid fossa of scapula
Type of joint: ball-and-socket
Movements of the shoulder joint
SHOULDER:
Flexion-Extension
Abduction-Adduction
External-Internal Rotation
SPECIALIZED:
Horizontal abduction-Horizontal adduction
Shoulder joint capsule
Loose but still vital for stability
Shoulder joint key ligament
Coracoacromial: key ligament for preventing severe dislocation of the humerus and frequently involved with impingement syndromes.
Specialized structures of the shoulder joint
- Coracoacromial arch:
Components: coracoacromial ligament+coracoid process+acromion process
Function: provides protective shelf over head of humerus and helps prevent superior dislocation of the humerus - Glenoid labrum
Description: fibrocartilage rim
Function: joint stability and shock absorption - Bursa:
Description: bursa located below coracromial arch
Function: cushion rotator cuff muscles from overlying coracoacromial arch
Scapular muscles and their actions
Posterior scapular muscles: (common action=scapular adduction)
A. Components: trapezius
Upper: scapular elevation
Scapular upward rotation
Scapular adduction
Middle: scapular adduction
Lower: scapular Depression
Scapular upward rotation
Scapular adduction
- Levator scapulae: scapular elevation
scapular downward rot.
scapular adduction - Rhomboids: scapular elevation
scapular adduction
scapular downward rotation
Anterior scapular muscles
- Serratus Anterior: scapular abduction
scapular upward rotation
scapular depression(lf) - Pectoralis minor
Rotator cuff muscles and actions
- Supraspinatus: shoulder abduction
stabilization of shoulder - Infraspinatus: shoulder external rotation
Stabilization of shoulder
Shoulder horizontal abduction
Component of SIT force coupl - Teres minor: same as infraspinatus
4.subscapularis: shoulder internal rotation
Stabilization of shoulder
Component of SIT force coupl
Other glenohumeral muscles and actions
- Pectoralis major:
Clavicle portion- shoulder flexion
Shoulder abduction ^90
Shoulder adduction
Sternal portion- shoulder extension
Shoulder adduction - Deltoid:
Anterior- shoulder flexion
Shoulder horizontal adduction
Shoulder internal rotation
Middle- shoulder abduction
Shoulder horizontal abduction
Posterior- shoulder extension
Shoulder horizontal abduction
Shoulder external rotation - Latissimus dorsi: shoulder extension
Shoulder adduction
Shoulder horizontal abduc.
Shoulder internal rotation
Depression of humerus - Teres major: shoulder extension
Shoulder adduction
Shoulder horizontal abduction
Shoulder internal rotation
Depression of humerus
Alignment and common deviations of the shoulder complex (Rolled Shoulders)
Description of rolled shoulders:
Position involving scapular abduction, shoulder internal rotation and in some cases, thoracic kyphosis of the spine.
- Correction:
A.strengthening: scapular adductors
Shoulder external rotators
Thoracic spinal extensors
B. Exercise: double shoulder external rotation with upper back arch
C. Stretch: shower internal rotators
D. Exercise: sitting arms overhead stretch
Winged scapula
- Description: medial border or lower angle of scapula projects backwards versus lying flat against ribcage.
- Correction
A. Strengthen: serratus anterior, lower trapezius
Exercise: push up plus and rows
Shoulder mechanics
Scapulohumeral rhythm
SIT force couple
Synergies
Scapulohumeral rhythm
Coordinated, linked, predictable movement between the scapula and humerus that functions to facilitate optimal shoulder mechanics.
Example: upward rotation of the scapula with shoulder abduction
SIT Force couple
Members of the rotator cuff muscles:
Subscapularis
Infraspinatus
Teres minor
Definition: the sit force couple acts to counter the upward pull of the deltoid muscle and facilitate desired shoulder abduction.
Synergies
Definition: use of a muscle or muscles to neutralize undesired actions of the prime mover(s)
Upward rotation of the scapula
Muscular analysis of fundamental shoulder movements
A. Shoulder flexion:
Plane: Sagittal
Axis: mediolateral
Primary muscles: anterior deltoid, pectoralis major
Sample movements: up phase of front arm raise or push up
B. Shoulder extension
Plane: Sagittal
Axis: mediolateral
Primary muscles: latissimua dorsi, pectoralis major
Sample movements: back phase of sitting row.
C. Shoulder abduction:
Plane: frontal
Axis: anteroposterior
Primary muscles: middle deltoid, supraspinatus
Sample movements: up phase of side arm raise
D. Shoulder adduction
Plane: frontal
Axis: anterioposterior
Primary muscles: latissimus dorsi, pectoralis major
Sample movements: down phase of single arm pull.
E. Shoulder external rotation
Plane: horizontal
Axis: vertical
Primary muscles: infraspinatus, teres minor
Sample movement: out phase of double external rotation
F. Shoulder internal rotation
Plane: horizontal
Axis: vertical
Primary muscles: subscapularis, teres major
Movement: in phase of single shoulder internal rotation.
Special considerations for the shoulder complex in dance
- Lifting the shoulders
- Wide scapulae
- Connection of the arms to torso
- Partnering and arm support of body weight
Elbow joint structure and movements
Compromised of: humeroulnar
Articulating bones: humerus and ulna
Landmarks: trochlea of humerus and trochlear notch of ulna
B. Humeroradial
Articulating bones: humerus and radius
Landmarks: capitulum of humerus and head of radius
- Hinge joint
- Flexion-extension
- Alignment: carrying angle- lateral deviation of the axis of the forearm relative to the axis of the humerus In anatomical position.
B. Elbow hyper extension
Key muscles of elbow
A. Anterior elbow muscles
1. Biceps brachii: elbow flexion, radioulnar supination 2. Brachialis: elbow flexion
B. Posterior elbow muscles
1. Triceps brachii: elbow extension
Radioulnar joint structure
- Upper radioulnar joint: pivot
- Lower radioulnar joint: pivot
- Movements: pronation-supination
Key muscles of radioulnar joints
A. Pronator teres:
Location: proximal forearm, anterior surface
Action: radioulnar pronation
B. Pronator quadratus:
Location: distal forearm, anterior surface
Action: radioulnar pronation
C. Supinator:
Location: proximal forearm, posterolateral
Action: radioulnar supination
D. Biceps brachii:
Location: anterior arm
Action: radioulnar supination and elbow flexion.
