kinesiology of the shoulder

KINESIOLOGYSHOULDER

By Hermizan Halihanafiah

College of Allied Health and Science, Malaysia

1

SHOULDER JOINT

• Glenohumeral joint

• Articulation surface – between head of humerus and glenoid fossa of scapula

• Ball and socket joint – allows 3 degrees of freedom

• Flexion/extension, abduction/adduction, internal/external rotation, horizontal adduction/horizontal abduction

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KinematicsShoulder abduction/adduction

• Occur in the frontal plane/anteroposterior axis of rotation

• Range of motion

- full abduction: 180 deg (120 shoulder abd + 60 deg scapular upward rotation)

- adduction : vice versa (120 shoulder add + 60 deg scapular downward rotation)

• Involve the head of humerus rolling superiorly and slide inferiorly within glenoid fossa.

• Without inferior slide, the humeral head stuck into the acromion ---- impingement (suprasapinatus tendon or subacromial bursa)

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Shoulder Impingement

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Kinematics

Shoulder flexion/extension

• Occur in sagittal plane/medial-lateral axis of rotation

• ROM

- full flexion: 120 deg shoulder flexion + 60 deg scapular upward rotation

- extension : reverse action of flexion + 40 – 60 deg of hyperextension

5

Kinematics

Shoulder internal/external rotation

• Occur in horizontal plane/vertical axis of rotation

• Rotation results in the anterior surface of humerus rotates medially/internally (internal rotation) or rotates laterally/externally (external rotation)

• ROM

- external rotation : about 90 deg (80-100 deg)

- internal rotation : about 70 deg (65 – 80deg)

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Kinematics

Shoulder horizontal abduction/horizontal adduction

• SPECIAL MOVEMENT

• Occur when shoulder 90 deg abd, humerus will move in horizontal plane

• Humerus move towards midline – horizontal adduction

• Humerus move away form midline – horizontal abduction

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Supporting Structure

• Shoulder joint – highly mobile (TRIAXIAL JOINT, LARGE ROM) but less stability

• Due to large, rounded head of humerus and the shallowness of glenoid fossa of scapula

• Strengthen by :1. Rotator cuff muscles2. Capsular ligaments3. Coracohumeral ligament4. Glenoid labrum5. Long head of the biceps

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ROTATOR CUFF MUSCLES

• ROTATOR CUFF MUSCLES – CENTRE OF STABILITY

• Consist of SITS; Supraspinatus, Infraspinatus, Teres minor and Subascapularis muscles

• Function – centralizing and stabilizing the humeral head within glenoid fossa

• Surround humeral head anteriorly, superiorly and posteriorly, and providing muscular force that pulls the humeral head towards glenoidfossa.

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Ligamentous Structure

Capsular lig

• Consist of superior, inferior and middle glenohumeral lig, attaches between the rim of gleoid gossa and anatomical neck of humerus

Coracohumeral lig

• Prevents inferior displacement of humeral head, prevent excessive motion of flexion, extension and external rotation, attaches between coracoid process of scapula and greater tubercle of humerus.

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Others Structure

Glenoid Labrum

• A fibrocartilaginous riing that encircles the edge of glenoid fossa, deepen the glenoid fossa (nearly doubling the function of glenoid fossa)

Long Head of the Biceps

• The proximal portion of the tendon wraps around the superior aspect of the humeral head (originates form supraglenoid tubercle), provide anterior stability of shoulder joint.

15

Scapulohumeral Rhythm• The full range of shoulder motion normally is combination

between the motion in glenohumeral and scapulothoracic joint.

• A natural rhythm/ratio between GH joint and scapulothoracicjoint --- 2:1

• That’s means for every 2 deg of shoulder abduction/flexion, the scapula must upward rotate roughly 1 deg. (vice versa for adduction/extension)

• The full ROM of shoulder abduction/flexion= 180 deg, which combination between 120 deg shoulder abduction/flexion + 60 deg scapular upward rotation.

180 degrees of shoulder abduction/flexion = 120 degrees of glenohumeral joint abduction +

60 degrees of scapulothoracic joint upward rotation

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Scapulothoracic (ST) Joint

• Not a truth joint

• Articulating between anterior surface of scapula to posterior thorax (ribs 2-7)

• Movements : permits scapular elevation/depression, protraction/retraction, upward/downward rotation

• Motion of ST joint is dependent on the combined movement of the acromioclavicular (AC) and sternoclavicular (SC) joint.

• The full 60 deg ST joint upward rotation = 30 deg of SC joint elevation + 30 deg AC joint upward rotation

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THE RELATIONSHIP BETWEEN AC, SC, ST AND GH JOINTS MOTIONS.

180 degrees of shoulder abduction/flexion = 120 degrees of GHJ abduction +

60 degrees of STJ upward rotation

60 degrees STJ upward rotation =30 degrees of SCJ elevation +

30 degrees of ACJ upward rotation

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SCAPULOTHORACIC JOINT MUSCLES

Primary Elevators of ST joint

• Upper fiber of trapezius

• Levator scapulae

• Rhomboids

Primary Depressor of ST joint

• Lower fiber of trapezius

• Latissimus dorsi19

Upper / Superior Fiber of Trapezius

• Origin – medial one third of

the superior nuchal line,

external occipital

protuberance and ligamentum

nuchae.

• Insertion – posterior border of

the lateral one third of the

clavicle.

• Action – scapular elevation

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Levator Scapulae• Origin – transverse process of

Superior four or five cervical

vertebrae.

• Insertion – superior vertebral

border of scapula

• Action – Elevates scapula and

rotates it downward.

• Nerve supply – dorsal

scapular nerve and cervical

spinal nerve

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Rhomboid Major

• Origin – Spine of 2nd to 5th

thoracic vertebrae

• Insertion – vertebral border

of scapula inferior to spine of

scapula

• Action – elevates and

adducts scapula and rotate it

downward; stabilize scapula

• Nerve – dorsal scapular

nerve

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Rhomboid Minor• Origin – Spine of 7th cervical

and 1st thoracic vertebrae.

• Insertion – Vertebrae border

of scapula superior to spine

• Action – elevates and adducts

scapula and rotate it

downward; stabilize scapula

• Nerve – dorsal scapular nerve

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Lower / Inferior Fiber of Trapezius

• Origin – spinous

process of T6-T12

• Insertion – spine of the

scapula

• Action scapular

depression and

adduction24

Latissimus Dorsi• Origin – Spines of inferior 6 thoracic

vertebrae (T6-T12), lumbar vertebrae

(L1-L5), crest of sacrum and illiac crest

of hip bone, inferior four ribs and

inferior angle of scapula.

• Insertion – Intertubecular sulcus of

humerus

• Action

– Extends, adduction and medial

rotation arm at shoulder joint.

• Nerve supply - Thoracodorsal nerve 25

SCAPULOTHORACIC JOINT MUSCLES

Primary upwards rotators of ST joint

• Upper fiber of trapezius

• Lower fiber of trapezius

• Serratus anterior

Primary downward rotators of ST joint

• Rhomboids

• Pectoralis minor

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Serratus Anterior

• Origin – Superior 8 or 9 ribs

• Insertion – vertebral border and

inferior angle of scapula

• Action

– Abduction and rotates the

scapula upward

– Elevate ribs when scapula

stabilized.

– Also known as “boxer’s

muscles”

• Nerve supply

– Long thoracic nerve27

Pectoralis Minor

• Origin

– 2nd - 5th ribs, 3rd – 5th ribs or 2nd – 4th ribs.

• Insertion

– Coracoid process of scapula

• Action

– Abduction scapula and rotates it downward

– Elevate the ribs during forced inhalation.

• Nerve supply

– Medial pectoral nerve 28

SCAPULOTHORACIC JOINT MUSCLES

Primary protractors of ST joint

• Serratus anterior

Primary retractors of ST joint

• Rhomboids

• Middle fiber of trapezius

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Middle Fiber of Trapezius

• Origin – spinous process

of T1 – T5

• Insertion – medial border

of the acromion process

of scapula, and superior

border of the spine of the

scapula.

• Action – scapular

adduction.30

Glenohumeral Joint Muscles

Primary GH Joint Abductors

• Anterior fiber of deltoid

• Middle fiber of deltoid

• Supraspinatus

Primary GH Joint Adductors

• Latissimus dorsi

• Teres major

• Pectoralis major (sternal head)31

Anterior Fiber of Deltoid

• Origin – anterior border of

the lateral one third of the

clavicle

• Insertion – deltoid

tuberosity

• Action – abduction,

flexion and middle

rotation arm at GH joint.32

Middle fiber of Deltoid

• Origin – lateral border and

superior surface of the

acromion process of the

scapula

• Insertion – deltoid

tuberosity

• Action – abduction arm at

GH joint

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Supraspinatus Muscle

• Origin – supraspinous fossa

of scapula

• Insertion – Greater tubercle

of humerus (anterior aspect)

• Action – initially abduction

(15 degrees) at shoulder

joint, stabilizing shoulder

joint

• Nerve supply -

Suprascapular nerve

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Latissimus Dorsi• Origin – Spines of inferior 6 thoracic

vertebrae (T6-T12), lumbar vertebrae

(L1-L5), crest of sacrum and illiac crest

of hip bone and inferior four ribs.

• Insertion – Intertubecular sulcus of

humerus

• Action

– Extends, adduction and medial

rotation arm at shoulder joint.

• Nerve supply - Thoracodorsal nerve

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Sternal origin of Pectoralis Major• Origin – anterior surface of

sternum, costal cartilage of 2nd -6th ribs.

• Insertion – greater tubercle and intertubercular sulcusof humerus

• Action – extend arm at shoulder joint.

• Nerve supply

– Medial and lateral pectoral nerve

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Teres Major• Origin – Inferior angle of

scapula

• Insertion – Intertubecularsulcus of humerus

• Action

– Extends arm at shoulder joint

– Assist in adduction and medial rotation of arm at shoulder joint.

• Nerve supply

– Lower subscapularnerve 37

Glenohumeral Joint Muscles

Primary GH Joint Flexors

• Anterior fiber of deltoid

• Pectoralis major (clavicular head)

• Coracobrachialis

• Biceps brachii

Primary GH Joint Extensors

• Latissimus dorsi

• Teres major

• Pectoralis major (sternal head)

• Posterior deltoid

• Long head of triceps38

Clavicle origin of Pectoralis Major

• Origin – medial half of anterior clavicle

• Insertion – greater tubercle and intertubercular sulcus of humerus

• Action – Flexion, adduction and medial rotation arm at shoulder joint.

• Nerve supply

– Medial and lateral pectoral nerve

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Coracobrachialis

• Origin - Coracoid process of

scapula

• Insertion - Middle of medial

surface of shaft of humerus.

• Action - Flexion and adduction

arm at shoulder joint.

• Nerve supply -

Musculocutaneous nerve

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Short head of Biceps

• Origin – Coracoid process of

scapula

• Insertion – radial tuberosity of

radius

• Action – Flexion forearm at

elbow joint, flexion arm at GH

joint and supination at

radioulnar joint.

• Nerve supply -

Musculocutaneous nerve41

Long head of Biceps

• Origin – Tubercle above the

glenoid cavity of scapula

(supraglenoid tubercle)

• Insertion – Radial tuberosity of

radius

• Action – flexion forearm at

elbow joint, flexion arm at GH

joint and supination forearm at

radioulnar joint.

• Nerve supply -

Musculocutaneous nerve42

Posterior Fiber of Deltoid

• Origin – inferior lip of the

crest of the spine of the

scapula

• Insertion – deltoid

tuberosity

• Action – extension and

lateral rotation arm at GH

joint.43

Long head of Triceps

• Origin – tubercle below to

glenoid cavity of scapula

(infraglenoid tubercle)

• Insertion – Olecranon of ulna

• Action - Extends forearm at

elbow joint , Extends arm at

shoulder joint

• Nerve supply - Radial nerve

Posterior View 44

Glenohumeral Joint Muscles

Primary GH Joint Internal Rotators

• Anterior fiber of deltoid

• Pectoralis major

• Latissimus dorsi

• Teres major

• Subscapularis

Primary GH Joint External Rotators

• Posterior deltoid

• infraspinatus

• Teres minor

45

Infraspinatus Muscle

• Origin – Infraspinous fossa

of scapula

• Insertion – Greater tubercle

of humerus (posterior

aspect)

• Action – Laterally rotation

and adduction arm at

shoulder joint

• Nerve supply -

Suprascapular nerve46

Teres Minor• Origin – Inferior lateral

border of scapula

• Insertion – Greater tubercle

of humerus (inferior aspect)

• Action – Laterally rotation,

extends and adduction arm

at shoulder joint

• Nerve supply – axillary

nerve

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Subscapularis Muscle

• Origin – subscapular

fossa of scapula

• Insertion – lesser tubercle

of humerus

• Action – Medial rotation

arm at shoulder joint

• Nerve supply – upper and

lower subscapular nerve48