Final Exam-Shoulder Girdle Flashcards
Upper Extremity
Shoulder Complex
Arm/Forearm
Wrist (Hand)
Shoulder Girdle
an “open” mechanical system
R and L sides not directly attached so they can move independently
Sternoclavicular Articulation
- articulation between the sternum and clavicle
- a modified ball-and-socket joint (mobile in frontal and transverse plane; limited sagittal movement)
Acromioclavicular Movement
articulation between acromion process and distal end of clavicle
BONY SUPPORT–weak
Scapulothoracic Articulation
- “physiological” articulation (no bone-to-bone connection) between the anterior surface of the scapula (scapular fossa) and the thoracic wall
- scapula rests on 2 muscles (serratus anterior and subscapularis)
- 60 degree ROM
Scapular Motions
Elevation and Depression
Protraction and Retraction
Upward and Downward Rotation
Scapulohumeral Rhythm
scapular rotation to facilitate shoulder movements (abduction and flexion)
- 1st 30 degree of abduction or 45 degrees of flexion–scapula moves to a position of stability on thorax
- beyond this initial range–a 5:4 ratio of glenohumeral to scapular movements
- for total ROM have a 2:1 ration (e.g. 180 degrees of abduction have 120 degrees of glenohumeral movement and 60 degrees of scapular movement)
Rhomboids
Elevation, Downward Rotation, Retraction
Pectoralis Minor
Depression, Downward Rotation, Protraction
Serratus Anterior
Protraction, Upward Rotation
Upper Trapezius/ Middle Trapezius
Elevation, Protraction, Upward Rotation
Lower Trapezius
Depression, Retraction
Levator Scapulae
Elevation, Retraction, Downward Rotation
Shoulder Joint (aka glenohumeral)
- articulation of humerus and glenoid fossa
- designed for mobility (greatest ROM of any joint in body)
- lacks bony and ligamentous support
- shallow glenoid fossa (1/4 size of humeral head)
- half-spherical humeral head
Labrum
- a lip of cartilage surrounding the joint
- increases depth of fossa
- increases contact area by 75%
- assists in holding the humerus in place
Coracohumeral Ligament
glenohumeral ligaments (superior, middle, inferior) -these ligaments merge with the articular capsule
Shoulder depends on ligamentous and muscular contributions for support
Articular capsule (2x volume of humeral head-laxity)
Anterior Support: capsule, labrum, glenohumeral ligaments 3 “reinforcements” in the capsule coracohumeral ligament, and fibers of the subscapularis and pec. major that blend into the joint capsule
Posterior Support: capsule, labrum, fibers from the teres minor and infraspinatus that blend into the capsule
Shoulder Ligamentous Support
- no ligament to prevent backward displacement
- fossa angle slightly anterior
- prevents backward displacement
Stabilizing Influence of Rotator Cuff
- muscles have a large stabilizing component when active
- all have a ‘large’ horizontal component
- so play a significant role in stabilizing the humerus agaist the glenoid fossa
External Rotation
infraspinatus and teres minor
Internal rotation
subscapularis
Horizontal Adduction
Pec major and Anterior Deltoid
Horizontal Abduction
Infraspinatus, Teres Minor, and Pos. Deltoid
Muscular Strength (Shoulder Complex) from Strongest to Weakest
Adduction Extension Flexion Abduction Internal rotation External rotation
Shoulder Loading
-ergonomists recumbent workers seated desk use arm position with 20 degrees or less of abduction and 25 degrees or less of flexion
Shoulder Girdle Injury
Sternoclavicular Joint
-low rate injury
- sprain caused by force which displaces shoulder anteriorly
- dislocation of medial end of clavicle medially, superiorly, and either anterior or posterior
- posterior dislocation particularly dangerous because trachea, esophagus, veins, etc. located behind
- dislocation in adults but usually fracture in children
Shoulder Girdle Injury
Acromioclavicular Joint
-force applied laterally to acromion process
- commonly known as shoulder separation
- range from mild sprain of AC ligament to complete AC dislocation with tearing of clavicular attachments of deltoid and trapezius and complete rupture of coracoclavicular ligament
- displaces the acromion anteriorly and inferiorly while clavicle does not move (95% of all dislocations for this joint)
- scenario-fall on an outstretched arm to break a fall
- force of impact transmitted through humerus such that entire scapula is displaced relative to unmoved clavicle
Dislocation or subluxation
- frequent due to lack of stability
- usually occur when should abducted and extremely rotated
ANTERIOR-INFERIOR dislocations most common (90%)
when arm is abducted, extended, and externally rotated
- usually caused by a large external force
- age of 1st dislocation inversely related to rate of recurrence (the younger you are, the more likely you are to have a recurrence)
Shoulder Joint Action: Abduction
Supraspinatus, Deltoid, Upper Pectoralis Major
Shoulder Joint Action: Adduction
Lattissimus Dorsi, Teres Major, Lower Pectoralis Major, Coracobrachialis, Triceps Brachii
Shoulder Joint Action: Flexion
Anterior Deltoid, Upper Perctoralis Major, Biceps Brachii, Coracobrachilias
Shoulder Joint Action: Extension
Latissimus Dorsi, Teres Major, Triceps Brachii, Lower Pectoralis Major, Posterior Deltoid
Shoulder Joint Action: Internal Rotation
Latissimus Dorsi, Teres Major, Pectoralis Major, Subscapularis
Shoulder Joint Action: External Rotation
Infraspinatus, Teres Major
Shoulder Girdle Action: Upward Rotation
Serratus Anterior, Upper and Lower Trapezius
Shoulder Girdle Action: Downward Rotation
Pectoralis Minor, Rhomboids
Shoulder Girdle Action: Elevation and Upward Rotation
Levator Scapulae, Serratus Anterior, Upper Trapezius, Rhomboids
Shoulder Girdle Action: Depression and Downward Rotation
Pectoralis Minor, Lower Trapezius, Rhomboids
Shoulder Girdle Action: Protraction
Seratus Anterior, Pectoralis Minor
Shoulder Girdle Action: Retraction
Lower Trapezius, Rhomboids
How to detect a torn Rotator Cuff
Using an Arthrogram Inject die into joint to see if it leaks out where the rotator cuff tendon is supposed to be.
Use an MRI
Soft Tissue Injuries
Often associated with overarm motions such as throwing
Preparatory phase: shoulder abducted to 90, shoulder ext rotation, scapular retraction, and elbow flexion
Anterior capsule and subscapularis muscle are susceptible to strain or tendinitis at the insertion on the lesser tubercle
Extreme External Rotation in Overarm Pitching
-external rotation terminated by forces from:
- anterior joint capsule and ligaments
- subscapularis
- pectoralis major
- triceps brachii
- teres major
- latissmus dorsi
Acceleration Phase
EXPLOSIVE PHASE CHARACTERIZED BY:
- initiation of elbow extension
- shoulder internal rotation
- maintenance of shoulder abduction at 90
- shoulder transverse adduction
- scapular protraction
-posterior capsule and labrum supsceptible to injury as anterior shoulder is tightened driving the humeral head backwards
Follow Through Phase
- rotator cuff works to decelerate shoulder’s internal rotation
- infraspinatus and teres minor very susceptible to muscle strain or tendinitis
Rotator Cuff Impingement
-impingement of supraspinatus tendon
2 THEORIES
- genetic: too narrow a space between acromion and humeral head
- overuse: repeated stretching of supraspinatus weakens its ability to stabilize the humerus leading to deltoid pulling humerus up and impingement of tissues
Swimmer’s Shoulder
RECOVERY
- near maximum tension in serratus anterior during recovery to rotate scapula and facilitate overhead arm movements
- fatigued serratus will not rotate scapula so rotator cuff muscles impinged
Swimmer’s Shoulder “Impingement Syndrome”
@ HAND ENTRY
- shoulder forced into extreme abduction, flexion and internal rotation
- allows prox head of humerus to rub across the supraspinatus tendon
- can “impinge” the supraspinatus tendon between humerus and coracoacromial ligament
- increased internal rotation when elbow is held in place and arm pushes back
- head of humerus is thrust forward close to ligamentous structure of shoulder joint where contact can occur
- increase likelihood of impingement
Swimmer’s Shoulder
AT COMPLETION OF ARM PULL
- shoulder adducted such that supraspinatus tendon is stretched over the head of the humerus
- cuts off blood supply to tendon
