Shoulder joint

KINESOLOGY OF THE SHOULDER JOINT PRESENTED BY :

DR.ASER MOHAMED KAMAL

PHYSICAL THERAPY

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

• Shoulder 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)

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

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)

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

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 muscles

2. Capsular ligaments

3. Coracohumeral ligament

4. Glenoid labrum

5. Long head of the biceps

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 glenoid

fossa.

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.

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.

Palpation of Bony Landmarks

of shoulder

Scapula:

1. Spine – From AC joint palpate across the upper part of the

posterior surface of the scapula. It is a long (3”) thin projection, which

runs medial to lateral, at T3 level.

2. Acromion process – Located on the lateral part of the shoulder,

right above the shoulder joint.

3. Coracoid process – Palpate under the lateral part of the clavicle

(about one inch below the anterior edge of the clavicle).

4. Medial (vertebral) border – The edge of the scapula closest to the

vertebral column (about 2 inches from the spinous processes). The

medial border runs in a superior-inferior direction.

5. Lateral (axillary) border – The lateral (or outer) edge of the scapula

located between the inferior angle and the shoulder joint.

6. Superior medial angle – Located above the vertebral border or

medial aspect of scapula, level T2.

7. Inferior angle – Located between vertebral and axillary borders.

The “point” at the bottom of scapula, level T7.

Clavicle:

“Collar bone” – anterior from sternum to acromion

Humerus:

1. Greater tuberosity – Located just below acromion when arm is

resting by the side. (proximal end of humerus)

2. Lesser tuberosity – Easiest to palpate with arm in shoulder external

rotation. Located medial to greater tuberosity on proximal end of

humerus.

3. Intertubercular (Bicipital) Grove – Located between greater and

lesser tuberosity; easiest to palpate with arm in external rotation.

4. Medial and lateral epicondyles – Palpated on medial and lateral

sides, respectively, of distal end of humerus (2 “bumps” on distal

end).

5. Medial and lateral supracondylar ridge – above the medial and

lateral epicondyles on distal end of humerus.

6. Olecxranon fossa – indentation on posterior of elbow

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 scapulothoracic joint

--- 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

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

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

SCAPULOTHORACIC JOINT MUSCLES

Primary Elevators of ST joint Primary Depressor of ST joint

- Upper fiber of trapezius - Lower fiber of trapezius

- Levator scapulae - Latissimus dorsi

- Rhomboids

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

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

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

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

Lower / Inferior Fiber of Trapezius

• Origin – spinous process of T6-T12

• Insertion – spine of the scapula

• Action scapular depression and adduction

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


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

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 nerve

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


Primary protractors of ST joint

• Serratus anterior

Primary retractors of ST joint

• Rhomboids

• Middle fiber of trapezius

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.

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)

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.

Middle fiber of Deltoid

• Origin – lateral border and superior surface of

the acromion process of the scapula


• Action – abduction arm at GH joint

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

Sternal origin of Pectoralis Major

• Origin – anterior surface of sternum, costal

cartilage of 2nd -6th ribs.

• Insertion – greater tubercle and

intertubercular sulcus of humerus

• Action – extend arm at shoulder joint.

• Nerve supply

– Medial and lateral pectoral nerve

Teres Major

• Origin – Inferior angle of scapula

• Insertion – Intertubecular sulcus of

humerus

• Action

– Extends arm at shoulder joint

– Assist in adduction and medial

rotation of arm at shoulder joint.

• Nerve supply

– Lower subscapular nerve


Primary GH Joint Flexors


• Pectoralis major (clavicular head)

• Coracobrachialis

• Biceps brachii

Primary GH Joint Extensors


• Teres major

• Pectoralis major (sternal head)

• Posterior deltoid

• Long head of triceps

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

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

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.


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.


Posterior Fiber of Deltoid

• Origin – inferior lip of the crest of the spine of the scapula


• Action – extension and lateral rotation arm at GH joint.

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


Primary GH Joint Internal Rotators


• Pectoralis major


• Teres major

• Subscapularis

Primary GH Joint External Rotators

• Posterior deltoid

• infraspinatus

• Teres minor

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 nerve

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

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 nerve

Education

Shoulder joint