The shoulder joint is formed by the articulation of the glenoid cavity of the scapula and the head of the humerus. It is a synovial, polyaxial ball and socket joint. The glenoid fossa is too small and shallow to stably hold the humeral head, so the joint is inherently weak. Stability is provided by the joint capsule, glenohumeral ligaments, labrum, rotator cuff muscles, and other accessory ligaments. Injuries like dislocations or rotator cuff tears can compromise the stability of the shoulder joint.

1. ANATOMY OF SHOULDER JOINT
DR BIPUL BORTHAKUR
PROFESSOR & HOD
DEPARTMENT OF ORTHOPAEDICS,SMCH

2. Shoulder joint
 Shoulder joint is formed by articulation of the scapula (glenoid cavity) and head of the humerus
 Glenohumeral joint

4. Type of joint
 It is a synovial joint
 Polyaxial
 Ball and socket variety.

5. Proximal articular surface
Glenoid fossa of scapula :
 Pyriform in shape
 Surface area and concavity of the glenoid fossa is increased by glenoid
labrum
 Glenoid labrum – fibro cartilaginous ribbon like structure
 Covered with hyaline cartilage.

7. Distal articular surface
The head of humerus :
 Hemispherical in shape
 Covered with hyaline cartilage

9. Shoulder joint – weak point
 Glenoid fossa is too small and shallow to hold the head of humerus
 The head is four times the size of glenoid cavity
 Structurally it is a weak joint

10. Stability of the joint : Ligaments
True ligament : Capsule
Accessory ligaments :All the accessory ligaments attach either to lesser or
greater tubercles of humerus
 Glenohumeral ligaments
 Transverse humeral ligament
 Coraco-humeral ligament
 Secondary socket/ ligament ( Coracoacromial arch)
 Glenoid labrum

11. True ligament : Capsule
 Loose fibrous covering
 Inner surface lined with synovial membrane
Proximal attachments :
 Margins of glenoid fossa
Distal attachments :
 Anatomical neck of humerus

12. Accessory ligaments
Glenohumeral ligaments :
Three :
 Superior band
 Middle band
 Inferior band
 Seen on inner side of anterior part of capsule

13. Glenohumeral ligaments cont..
Proximal attachment : (Glenoid )
 All 3 bands attached to upper end of glenoid fossa
Distal attachment : (Humerus)
 Upper band : Top of lesser tubercle
 Middle band : Lesser tubercle deep to the tendon of subscapularis
 Lower band : Shaft just below the lesser tubercle

14. Transverse humeral ligament
 It is broad band which passes between the humeral tubercles
 It is attached superior to the epiphyseal line
 Long head of biceps tendon passes out deep to this ligament

15. Coraco-humeral ligament
 Origin - Lateral margin of root of coracoid process
 Insertion - greater tuberosity of humerus

16. Coracoacromial ligament
 Triangular band
Base : Attached to lateral margin of coracoid process
Apex : Attached to tip of acromion
 Coracoid process, ligament and acromion together form – Coracoacromial
arch (which forms secondary socket for the joint)

18. Glenoid labrum
 Fibro cartilaginous ribbon like structure
 Attached to margins of the glenoid cavity
 Increases the depth of the glenoid cavity.
 Lined by hyaline cartilage

20. Rotator cuff
 Laxity and weakness of joint is compensated by rotator cuff
Tendons of rotator cuff :
 Supraspinatus
 Infraspinatus
 Teres minor
 Subscapularis

22. Rotator cuff cont..
 Expansions from these tendons fuse with capsule
 Strengthens the capsule all around ( except inferiorly )
 Injury to rotator cuff result in recurrent dislocation .

23. Relations of shoulder joint
 Muscles
 Bursae
 Vessels and nerves

24. Relations of shoulder joint: Muscles
Anteriorly :
 Subscapularis
 Coracobrachialis
 Short head of biceps
 Deltoid
Posteriorly :
 Infraspinatus
 Teres minor
 Deltoid

25. Cont…
Superiorly :
 Long head of biceps inside the capsule
 Supraspinatus outside the capsule
Inferiorly :
 Long head of triceps
 Deltoid covers superiorly, anteriorly, posteriorly and laterally.

27. Bursae related to shoulder joint
Subacromial bursa :
 Lies between deltoid muscle and capsule
 Does not communicate with joint
 Extends between supraspinatus and acromion and coracoacromial arch
 Longest bursa in the body

29. Blood supply
Arterial supply :
 Anterior circumflex humeral artery
 Posterior circumflex humeral artery
 Suprascapular artery
 Circumflex scapular branch of subscapular artery
Venous drainage :
Corresponding veins

31. Nerve supply
 Lateral pectoral nerve
 Suprascapular nerve
 Axillary nerve (posterior division)

33. Movements at shoulder joint
 Flexion and extension
 Adduction and abduction
 Medial and lateral rotation
 Circumduction

35. Flexion and extension : Transverse
Axis
Flexors of shoulder joint :
 Pectoralis major (Clavicular part)
 Deltoid (anterior fibres)
 Coracobrachialis and assisted by biceps
Extensors of shoulder joint :
 Deltoid (posterior fibres )
 Teres major
 Latissimus dorsi and pectoralis major (sternocostal part)

36. Abduction and Adduction : Antero-
posterior axis
Abductors of shoulder joint :
 Supraspinatus :0-30
 Deltoid(middle fibres) : 0-90
 Serratus anterior and trapezius : 90-180
Adductors of shoulder joint :
 Pectoralis major
 Latissimus dorsi
 Teres major
 Coracobrachialis
 Biceps (short head )

37. Medial and lateral rotation :
Longitudinal axis
Medial rotation :
 Pectoralis major
 Deltoid (anterior fibres)
 Latissimus dorsi
 Teres major and subscapularis
Lateral rotation :
 Infraspinatus
 Deltoid (posterior fibres ) and teres minor

38. Circumduction
 Combination of 3 axis
 Combination of all the muscles around shoulder

39. Anterior glenohumeral dislocation
 Trauma to the upper extremity with the shoulder in abduction, extension,
and external rotation.
 BANKART lesion – Avulsion of anteroinferior labrum off the glenoid rim. It
may be associated with a glenoid rim fracture (Bony Bankart)
 Hills-Sachs lesion : A posterolateral head defect is caused by an
impression fracture on the glenoid rim.

40. Inferior glenohumeral
dislocation(Luxatio Erecta)
 Most common in elderly individuals.
 It results from a hyperabduction force causing impringement of the
humerus on the acromion which leaves the humeral head out inferiorly
 Patient typically present in salute fashion
 Humeral head is typically palpable on the lateral chest wall and axilla.

41. Rotator cuff disorders
 Impingement : The muscle most commonly involved is supraspinatus as it
passes beneath the acromion and the acromioclavicular ligament. This
space beneath which the supraspinatus tendon passes is of fixed
dimensions
Swelling of this muscle causes excessive fluid within the
subacromial/subdeltoid bursa or subacromial body spurs may produce
significant impingement when arm is abducted

42. Cont..
 Tendinopathy : The blood supply to the supraspinatus tendon is relatively
poor. Repeated trauma in certain circumstances makes the tendon
susceptible to degenerative changes which may result in calcium
deposition producing extreme pain

43. Subacromial bursitis
 It is inflammation of the bursa that separates the superior surface of the
supraspinatus tendon from the overlying coraco-acromial ligament,
acromion and coracoid and from the deep surface of the deltoid muscle.

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