JOINTS OF UPPER LIMB

DESCRIBE THE SHOULDER JOINT UNDER THE FOLLOWING HEADINGS (LE)

Articular ends,Capsule and ligaments,

Relations ,Movements and muscles producing them,Blood supply and nerve supply,Add a note on applied anatomy.

Shoulder joint is a ball and socket variety of synovial joint.

Articular ends

The joint is formed by the articulation of scapula and the head of humerus. Structurally it is a weak joint because the glenoid cavity is too small and shallow to hold the head of humerus in place.

The joint permits great mobility.

Capsule and ligaments

Fibrous capsule

Gleno - humeral ligaments

Glenoidal labrum

Coraco humeral ligament

Transverse humeral ligament

Fibrous capsule –

It Is loose and permits free movements. It is least supported inferiorly. Attachments of the capsule –

Medially –scapula beyond the supraglenoid tubercle and margins of the glenoidal labrum

Laterally- anatomical neck of humerus Inferiorly - to the surgical neck of humerus.

Superiorly - it is deficient for the passage of tendon of long head of biceps.

Gleno - humeral ligaments

The fibrous capsule is reinforced anteriorly by bands called superior , middle and inferior Gleno - humeral ligaments.

Glenoidal labrum

It is a fibrocartilagenous rim which covers the margins of glenoid cavity.

Coraco humeral ligament

Extend from the root of coracoid process to the neck of humerus. It gives strength to the capsule.

Transverse humeral ligament

Bridges the upper part of bicipital groove of humerus.

The tendon of long head of biceps passes deep to the ligament

Relations

Superiorly

Deltoid, Supraspinatus, Subacromial bursa, Coracoacromial arch

Inferiorly

Long head of triceps brachii

Posteriorly

Infraspinatus, teres minor and deltoid

With in the joint

The tendon of long head of biceps brachii.

Blood supply

Arterial supply

Anterior and posterior circumflex humeral artery Suprascapular artery

subscapular artery

Venous drainage

Anterior and posterior circumflex humeral veins Suprascapular vein

subscapular vein

Nerve supply axillary nerve musculocutaneous nerve suprascapular nerve

Movements of shoulder joint

The movements are considered in relation to scapula rather than in relation to sagittal and coronal planes.

a)Flexion and extension

b)Abduction and adduction

c)Medial and lateral rotation

d)Circumduction

Muscles involved in movements of shoulder joint are

MOVEMENTS	MAIN MUSCLES	ACCESSORY MUSCLES
Flexion	Pectoralis major	Biceps brachii
	Deltoid	Coracobrachialis
		Pectoralis major
Extension	Deltoid	Teres major
	Latissimus dorsi	Long head of triceps
Abduction	Supraspinatus 0 – 150	-
	Deltoid 150 - 900
	Serratus anterior 900-1800
	Trapezius 900-1800
Adduction	Pectoralis major	Teres major
	Latissimus dorsi	coracobrachialis
	Short head of biceps
	brachii
	long head of triceps brachii
Medial rotation	Pectoralis major	subscapularis
	Anterior fibres of deltoid
	Latissimus dorsi
	Teres major
Lateral rotation	Deltoid	-
	Infraspinatus
	Teres minor

Applied anatomy

1)Dislocation-

Shoulder joint is more prone for dislocation than any other joint in the body.

This is due to laxity of the capsule and disproportionate size of articular surfaces. Dislocation occurs inferiorly often injuring the axillary nerve.

The dislocation is usually caused by excessive extension and lateral rotation of humerus.

Frozen shoulder

Occurs due to shrinkage of joint capsule.

Patient complains of pain and stiffness in the joint.

ABDUCTION AND ADDUCTION MOVEMENT AT SHOULDER JOINT (SE)

Abduction and adduction occur at right angles to the plane of flexion and extension

Muscles bringing about abduction and adduction at the shoulder joint are

movements	Main muscles	Accessory
		muscles
Adduction	Pectoralis major	Teres major
	Latissimus dorsi	coracobrachialis
	Short head of biceps
	brachii
	Long head of triceps
	brachii
Abduction	Supraspinatus
	Deltoid
	Serratus anterior	-
	Upper and lower fibres of
	trapezius

Abduction of shoulder

Abduction occurs at 1800 .

The movements occur partly at the shoulder joint and partly at the shoulder girdle. The humerus and scapula move in the ratio of 2: 1 throughout abduction.

For every 150 of elevation 100 occur at shoulder joint and 50 due to movement of scapula.

CORACOACROMIAL ARCH – ATTACHMENTS AND FUNCTIONS (SA) Coracoacromial arch is formed by the coracoid process , acromion process and coracoacromial ligament between them.

Function

This ligamentous structure forms a protective arch for the head of humerus above and prevents its superior displacement above the glenoid cavity.

GLENOHUMERAL LIGAMENTS (SA)

Glenohumeral ligaments are 3 thickenings in the anterior part of fibrous capsule of shoulder joint. They are visible only from the interior of the joint.

The ligaments are -

superior glenohumeral ligament middle glenohumeral ligament

inferior Glenohumeral ligament

These ligaments strengthen the capsule and help in stability of the shoulder joint

MUSCLES PRODUCING ABDUCTION OF SHOULDER JOINT (SA) Abduction is movement of upper limb away from the midline of the body in a coronal plane

The muscle producing abduction are Supraspinatus- first 15 degrees Deltoid- 15 to 90 degrees

Serratus anterior and Upper and lower fibres of trapezius- over 90 degrees by scapular rotation.