Shoulder joint

Dr Rajesh Arora M.B.B.S, M.S.(ANATOMY) Professor Department of Anatomy S.M.S. Medical College, Jaipur

Shoulder girdle

• It consist of- two bones three joints -scapula - gleno-humeral -clavicle - acromio-clavicular - sterno-clavicular

Type of joints

• Sterno-clavicular-Synovial ,Saddle variety.

• Acromio-clavicular-Synovial, Plane variety.

• Glenohumeral-Synovial, Multiaxial, Ball and Socket variety.

Ligaments of Sterno-clavicular joint

• Capsular ligament• Sterno-clavicular ligament- anterior and

posterior• Interclavicular ligament• Costo-clavicular ligament- Anterior Lamina Posterior Lamina. Articular disc - Fibrocartilagenous

Sterno - clavicular joint

Ligaments of Acromio-clavicular joint

• Fibrous capsule• Acromio-clavicular ligament• Coraco-clavicular ligament - Conoid part - Trapezoid part• Coraco-acromial ligament

Acromio-clavicular joint

LIGAMENTS OF SHOULDER JOINT(Glenohumeral Joint)

• Fibrous capsule• Glenohumeral ligament -Superior band - Middle band - Inferior band• Coraco-humeral ligament• Transverse-humeral ligament

Glenohumeral Ligament

Glenoid labrum

• Fibro-cartilagenous rim• Triangular in cross section• Attach to peripheral margin of glenoid cavity

except above .• Deepens the glenoid fossa and forms pliable

cushion for ball to roll.

Glenoid labrum

Relations of joint• Above- Deltoid, supraspinatus, Subacromial

bursa ,and coraco-acromial arch.• Below-Quadrangular space transmitting axillary

nerve and posterior circumflex humeral vessels,long head of triceps.

• In front-Subscapularis,coracobrachialis and short head of biceps .

• Behind-Infraspinatus and teres minor.• Within capsule-long head of biceps.• Deltoid muscle covers the joint in front ,behind

and laterally.

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AnteriorlySubscapularis,coracobrachialis and short head of biceps .

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Posteriorly: • Infraspinatus• Teres minor muscles.

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Superiorly:1. Deltoid muscle 2. Coracoacromial ligament3. Subacromial (subdeltoid) bursa4. Supraspinatus muscle & tendon

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1. the long head of the triceps muscle

2. the axillary nerve

3. the posterior circumflex humeral vessels

Inferiorly:

Factors maintaining stability of shoulder joint

• The glenoid labrum deepens the socket.• Supraspinatus,tension of upper part of the capsule

and coraco-humera ligament prevent downward displacement.

• Tendons of subscapularis, supraspinatus, infraspinatus and teres minor blend with fibrous capsule form the musculo-tendinous rotator cuff act as gardian of the joint.

• The long head of biceps and coracoacromial arch prevents upward dislocation of the humerus.

BURSAE IN RELATION TO SHOULDER JOINT

• Communicating-Subscapular bursa -Infraspinatous bursa• Noncommunicating – -subacromial-largest bursa of the body.

-Above acromian process -Between capsule and coracoid process -Behind coracobrachialis -Between teres minor and long head of triceps -In front and behind the tendon of latissimus dorsi

Bursae

Blood supply and Nerve supply

• Vascular supply - Anterior and posterior circumflex humeral,

suprascapular and circumflex scapular vessels. • Nerve supply-

The capsule is supplied by the suprascapular nerve (posterior and superior parts), axillary nerve (anteroinferior) and the lateral pectoral nerve.

Movements of the Shoulder

• Flexion• Extension• Abduction• Adduction• External Rotation• Internal Rotation• Circumduction

Plane of movement

• Abduction and adduction occurs at the plane of scapula.

• Flexion and extension occurs 90 degree to the plane of scapula.

The three mutually perpendicular axes around which the principal movements of flexion-extension (A), abduction-adduction (B) and medial and lateral rotation (C) occur at

the shoulder

Flexion• 90 degree movement• Muscles involved

A.Deltoid (anterior fibers)

B.Pectoralis Major (clavicular fibers)

C.CoracobrachialisD.Biceps

Extension• 45 degrees• Muscles involved:

A. Deltoid (posterior fibers)

B. Teres MajorC.Latissimus DorsiD. Pectoralis Major

(sternocostal fibers)

Adduction

• 45 degrees• Muscles Involved:

A. Pectoralis MajorB. Latissimus DorsiC. Teres MajorD. Coracobrachialis

Abduction• 180 degrees• Muscles Involved:

A.SupraspinatusB.DeltoidC.Serratus AnteriorD.InfraspinatusE.Trapezius

Abduction

• Out of total 180 degree elevation, humerus move 120 degree at shoulder joint and the remaining 60 is done by the scapula at the joints of shoulder girdle

Abduction• Supraspinatus initiate the abduction upto15 degree• Further 15 to 90 degree abduction is done by Deltoid

muscle.• Infraspinatus and Teres minor rotate the humerus

laterally to overcome the impindgement of greater tubercle against coraco-acromial arch.

• Contraction of upper and lower fibres of Trepizius and lower five digitations of Serratus anterior rotate the scapula and assist the abduction.

• Middle fibres of trepizius stabilize the scapula during abduction.

External Rotation

• 80-90 degrees

• Muscles Involved:A. InfraspinatusB.Teres MinorC.Deltoid(posterior

fibres)

Internal Rotation

• 55 degrees• Muscles Involved:

A.SubscapularisB.Pectoralis MajorC.Latissimus DorsiD.Teres MajorE.Deltoid (anterior

fibers)

Circumduction This is a movement in

which the distal end of the humerus moves in circular motion while the proximal end remains stable

• It is formed by flexion, abduction, extension

and adduction. Successively

Dislocation of acromioclavicular joint

DISLOCATIONS OF THE SHOULDER JOINT

• The shoulder joint is the most commonly dislocated large joint.

Anterior-Inferior Dislocation

• Sudden violence applied to the humerus with the joint fully abducted pushes the humeral head downward onto the inferior weak part of the capsule, which tears, and the humeral head comes to lie inferior to the glenoid fossa.

• A subglenoid displacement of the head of the humerus into the quadrangular space can cause damage to the axillary nerve.

• This is indicated by paralysis of the deltoid muscle and loss of skin sensation over the lower half of the deltoid.

• Downward displacement of the humerus can also stretch and damage the radial nerve.

Rotator cuff tendonitis• Lesions of the rotator cuff are a

common cause of pain in the shoulder region.

• Excessive overhead activity of the upper limb may be the cause of tendinitis, although many cases appear spontaneously.

• During abduction of the shoulder joint, the supraspinatus tendon is exposed to friction against the acromion.

• Under normal conditions the amount of friction is reduced to a minimum by the large subacromial bursa, which extends laterally beneath the deltoid.

• Degenerative changes in the bursa are followed by degenerative changes in the underlying supraspinatus tendon, and these may extend into the other tendons of the rotator cuff.

• Clinically, the condition is known as subacromial bursitis, supraspinatus tendinitis, or pericapsulitis.

• It is characterized by the presence of a spasm of pain in the middle range of abduction when the diseased area impinges on the acromion.

RUPTURE OF THE SUPRASPINATUS TENDON

In advanced cases of rotator cuff tendinitis, the necrotic supraspinatus tendon can become calcified or rupture.

Rupture of the tendon seriously interferes with the normal abduction movement of the shoulder joint. The main function of the supraspinatus muscle is to hold the head of the humerus in the glenoid fossa at the commencement of abduction. The patient with a ruptured supraspinatus tendon is unable to initiate abduction of the arm. However, if the arm is passively assisted for the first 15° of abduction, the deltoid can then take over and complete the movement to a right angle.

Shoulder joint pain• The synovial membrane, capsule,

and ligaments of the shoulder joint are innervated by the axillary nerve and the suprascapular nerve.

• The joint is sensitive to pain, pressure, excessive traction, and distension.

• The muscles surrounding the joint undergo reflex spasm in response to pain originating in the joint, which in turn serves to immobilize the joint and thus reduce the pain.

• Injury to the shoulder joint is followed by pain, limitation of movement, and muscle atrophy owing to disuse.