Kinesiology Exam 3

Shoulder Girdle

Sternoclavicular joint

-diarthrodial classification (arthrodial-gliding)

-movements of clavicle: anterior, posterior, superior, inferior, some rotation

-supported by: anterior and posterior SC ligaments

acromioclavicular joint

-diarthrodial classification (arthodial)

-supported by: coracoclavicular ligaments and superior and inferior acromioclavicular ligaments 

-often injured 

scapulothoracic joint

not a true synovial joint, scapula moves on the rib cage 

-movement depends on SC and AC joints

-supported dynamically by: muscles not ligaments 

protraction of scapula

abduction, moves laterally away

-putting arms out in front of you

retraction of scapula

adduction, squeezes shoulder blades together

downward rotation

returning inferior angle inferomedially towards spinal column, shoulder blades going back to normal position

upward rotation

turning glenoid fossa upward and moving inferior angle superolaterally away from spinal column

depression

downward movement, returning scapula to normal postion

elevation

upward movement, shrugging the shoulders

protraction and retraction plane and axis

transverse plane, vertical axis 

-considered a rotational movement 

frontal plane, sagittal axis movements

upward and downward rotation, elevation and depression

lateral tilt

during protraction, scapula rotates on vertical axis

-posterior movement of medial border and anterior movement of lateral border

medial tilt

-during extreme retraction

-anterior movement of medial border and posterior movement of lateral border

anterior tilt

-occurs during glenohumeral hyperextension

-superior border moves anteroinferiorly and inferior angle moves posterosuperiorly 

posterior tilt

-occurs during glenohumeral hyperflexion

-superior border moves posterosuperiorly and inferior angle moves anteroinferiorly

functions of muscles

stabilize scapula so joint has stable base for moving humerus, support and enhance joint movement

Glenohumeral joint

attached to the axial skeleton by the clavicle at SC joint, requires significant amount of laxity, instability problems are common

classification of the glenohumeral joints

enarthrodial, multiaxial ball and socket joint 

Purpose of glenoid labrum

enhances stability and deepens joint socket, cartilaginous ring

Purpose for ligaments

provide stability, are quite lax until extreme ranges of motion are reached

Greater mobility = 

less stability 

Why is the shoulder joint frequently injured?

shallowness of glenoid fossa, laxity of ligaments, lack of strength and endurance in muscles

Shoulder joint abduction

shoulder girdle upward rotation and elevation

shoulder joint adduction

shoulder girdle downward rotation, depression

shoulder joint flexion

shoulder girdle elevation and upward rotation

shoulder joint extension

shoulder girdle depression and downward rotation

shoulder joint internal rotation

shoulder girdle protraction

shoulder joint external rotation

shoulder girdle retraction

shoulder joint horizontal abduction

shoulder girdle adduction

shoulder joint horizontal adduction

shoulder girdle protraction

Intrinsic muscles

originate of scapula and clavicle, insert on the humerus 

deltoid, coracobrachialis, teres major, rotator cuff 

Deltoid

anterior, posterior, and middle fibers

upright rows, front plate raises, and shoulder press

rotator cuff

supraspinatus, infraspinatus, ters minor, subscapularis

• stabilize humeral head in glenoid fossa

frequently injured, vital in maintaining humeral head in correct position within glenoid fossa while more powerful muscles move humerus through its wide range of motion

supraspinatus

assists in abduction 

infraspinatus

assists in external rotation, horizontal abduction, extension

teres minor

assists in external rotation, horizontal abduction, extension

subscapularis

assists in internal rotation, adduction, extension

teres major

assists in extension, internal rotation, and adduction 

coracobrachialis

assists in flexion, adduction, horizontal adduction

extrinsic muscles

originate on trunk, insert on humerus

latissimus dorsi, pectoralis major

latissimus dorsi

assists in adduction, extension, internal rotation, horizontal abduction 

Pectoralis major

upper fibers (clavicular head), lower fibers (sternal head)