SHOULDER JOINT

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Objectives Shoulder joint - Type Articular surfaces Ligaments Movements & muscles bringing

about the movements Blood supply Nerve supply Structures undercover of deltoid Applied anatomy

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Shoulder joint – Type

Also known as gleno-humeral joint

Type – multi-axial ball & socket type of synovial joint

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Shoulder joint – Articular surfaces Ball – spheroidal

head of humerus, 1/3rd of a sphere, directed medially,

upwards & backwards

Covered by hyaline articular cartilage – thickest in centre & thinner at periphery

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Shoulder joint – Articular surfaces Socket – pear-shaped, small &

shallow glenoid cavity of scapula

Directed upwards, forwards & laterally

hyaline articular cartilage – thin – centre; thick - periphery

Fossa deepened - glenoidal labrum - fibro-cartilaginous, attached to its peripheral margin

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Shoulder joint – Ligaments Fibrous capsule Synovial membrane Glenoid labrum Glenohumeral

ligaments Coraco-humeral

ligament Transverse humeral

ligament

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Ligaments - Fibrous capsule Loose envelope

permitting free movements

Medially – peripheral margin of glenoid cavity outside the labrum, includes origin of long head biceps brachii

Laterally – anatomical neck of humerus

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Ligaments - Fibrous capsule Deficient at two areas At upper end of

intertubercular sulcus - passage - tendon of long head of biceps

Infero-medially – it extends about 1 cm below to enroach on surgical neck of humerus

Supported by expansions - rotator cuff muscles

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Ligaments - Synovial membrane Lines the capsule Reflected along the

intra-capsular part of neck upto the articular cartilage of humeral head.

Synovial sheath extends along the long head of biceps brachii

Ligaments - Glenoid labrum Fibro-cartilaginous rim Attached to peripheral

margin of glenoid cavity except above – long head of biceps brachii

Deepens the glenoid fossa & also forms a pliable cushion for the ball to roll

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Ligaments - Glenohumeral ligaments Three fibrous bands

derived - thickening of the anterior part of fibrous capsule

Can be seen from within the joint

Converge upward & medially to supero-medial margin of glenoid cavity & blends with labrum

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Ligaments - Glenohumeral ligaments Superior band – lies

parallel to anterior edge of biceps tendon & attached to upper end of lesser tubercle of humerus

Middle band – attached ot lower part of lesser tubercle

Inferior band – lower part of anatomical neck of humerus

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Ligaments - Coraco-humeral ligament Thick band in the

upper part of capsule & extends from lateral border of coracoid process to anatomical neck of humerus b/w greater & lesser tubercle

Resists lateral rotation & adduction

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Ligaments - Transverse humeral ligament Connects two

lips of upper part of intertubercular sulcus & acts as retinaculum

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Rotator cuff Musculo-tendinous

cuff Formed -

supraspinatus, infraspinatus, subscapularis & teres minor – tonic contractions keep ball in contact with socket

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Stability Coraco-acromial

arch – secondary socket for head of humerus

Musculo-tendinous cuff

Glenoidal labrum

Relations of joint Above –

supraspinatus, subacromial bursa, coraco-acromial arch

Below – quadrangular space

In front – subscapularis, coracobrachialis & short head of biceps

Behind – infraspinatus, teres minor

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Bursae in relation to joint Subacromial bursa

– b/w supraspinatus & coraco-acromial arch, extends laterally b/w deltoid & greater tubercle; acts as secondary socket

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Bursae in relation to joint Subscapular bursa –

b/w subscapularis tendon & fibrous capsule; communicates with joint cavity - oval gap b/w superior & middle glenohumeral ligaments

Infraspinatus bursa

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Movements Movement Axis Muscles

Flexion Plane parallel to surface of glenoid cavity

Pectoralis major – clavicular head, deltoid – anterior fibres

Extension Deltoid – posterior fibres, latissimus dorsi

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Movements Movement Axis Muscles

Adduction Perpend- icular to plane of flexion & extension

Pectoralis major, teres major, Deltoid – anterior & posterior fibres, latissimus dorsi, coracobrachialis, long head of triceps

Abduction Supraspinatus – 0-150

Deltoid – middle fibres-15-900

Serratus anterior, trapezius – 90 – 1800

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Movements Movement Axis Muscles Medial rotation

Vertical Pectoralis major, teres major, Deltoid – anterior fibres, latissimus dorsi.

Lateral rotation

Deltoid – posterior fibres, infraspinatus, teres minor

Movements Circumduction –

succession of flexion, extension, adduction & abduction movements

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Blood supply Anterior & posterior

circumflex humeral vessels

Supra & subscapular vessels

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Nerve supply

Axillary nerve Musculocutaneous nerve Suprascapular nerve

Structures under cover of deltoid Bones Muscles Vessels & nerves Joints & ligaments Bursa

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Structures under cover of deltoid Bones – coracoid

process; lesser & greater tubercle, intertubercular sulcus, upper part of shaft & surgical neck of humerus

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Structures under cover of deltoid Muscles –

pectoralis major & minor, coracobrachialis, both headsof biceps brachii, latissimus dorsi, long head of triceps, rotator cuff muscles

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Structures under cover of deltoid Vessels & nerves

– anterior & posterior circumflex humeral vessels, axillary nerve

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Structures under cover of deltoid Joints &

ligaments – Shoulder joint & its ligaments; Coraco-acromial ligament

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Structures under cover of deltoid Bursa –

subacromial bursa

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Radiology of shoulder joint

Shoulder joint dislocation

Common due to laxity of ligaments & disproportionate articular surfaces. Inferior dislocation common & nerve damaged is axillary nerve

Shoulder joint inflammation

An inflammation of the shoulder joint can cause pain and restricted joint movement.

Painful arc syndrome

Chronic thickening of tendon of supraspinatus – pain b/w 60 & 120 abduction – impingement of tendon against coraco-acromial arch.

Frozen shoulder/ Adhesive capsulitis Causes

restriction of motion in the shoulder joint.

Causes the capsule surrounding the shoulder joint to contract and form scar tissue.

Bursitis

Arthodesis of shoulder ( surgical fixation) Optimum

position – 450

abduction & 200 flexion

Osteoarthritis

Arthroplasty Osteoarthritis -

joint replacement by metallic prosthesis

Hemiarthroplasty – joint surface of humerus only is replaced

Total arthroplasty – joint surface of humerus & glenoid surface is replaced

Can you? Describe the shoulder joint under the following

headings – Type Articular surfaces Ligaments Movements & muscles bringing about the

movements Applied anatomy Rotator cuff

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To summarize Shoulder joint - Type Articular surfaces Ligaments Movements & muscles bringing about the

movements Blood supply Nerve supply Structures undercover of deltoid Applied anatomy

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