Welcome Everybody To My Presentation On Shoulder joint

Introduction It is a ball and socket type of synovial joint It is a multiaxial spheroidal jt Roughly hemispheric head of the humerus form the ball and shallow glenoid fossa of scapula form the socket. Skeletally jt is weak. It depends for stability and support on it’s surrounding muscle rather than it’s shape and ligaments. Only one third of humeral head is in contact with the glenoid fossa at any time.

Angle of inclination: in the frontal plane, the axis of the head and neck of humerus form an angle of 130°-140° with the long axis of shaft of femur.Because of this angulation, the centre of the humeral head lies about 1cm medial to the long axis. Angle of retroversion: an angle to the shaft of the humerus, the axis of the head and neck is rotated backwords against the shaft some 30°-40°, this is caled the angle of retroversion.

Articular surface Two articular surface:  Glenoid fossa:  glenoid fossa is situated at the supero-lateral angle of the scapula  faces laterally, anteriorly and slightly superiorly.  Concavity of glenoid fossa is irregular and less deep than convexity of head of the humerus.  The articular surface the fossa is little more than the head of the humerus  It ls covered by hyaline cartilage  Hyaline cartilage is thinner centrally and thickest peripharally

 Head of the humerus :  It represents two-fifths of a sphere  It faces superiorly, medially and anteriorly  Covered by hyaline cartilage  On the humerus hyaline cartilage is thickest centrally and thinner peripherally

Joint capsule It is like a cylindrical sleeve and situated between two bones Majority fibres of the capsule passes horizontally between scapula and humerus. But some oblique and transversre fibres are also found On the scapula, the capsule attaches just outside the glenoid labrum anteriorly and inferiorly On the humerus, capsile attaches to the anatomical neck,medial to the greater and lesser tubercle

Continuation Anterior part of the capsule is thickened and strengthened by three glenohumeral ligaments. Superoposterior part is strengthened by coracohumeral ligament In anatomical position of the arm the lower part of the capsule is lax and forms a redundant fold. In abduction of arm lower part become s taut

Continuation It is supported by the:  supraspinatus (above)  Infraspinatus and teres major (behind)  Subscapularis (in front)  Long head of triceps (below) Capsule has two or three openings:  Below the coracoid process  Between two tubercles  Inbursa undea the infraspinatous tendon

Synovial membrane This lines the capsule and covers parts of the anatomical neck The synovial membrane is reflected from the margin of the glenoid cavity over the labrum The tendon of the long head of the Biceps brachii passes through the capsule and is enclosed in a tubular sheath of synovial membrane

Glenonoid labrum  It is lintra-articular structure  It is a fibro-cartiliginous rim round the glenoid fossa  It is triangular in section  4mm deep  It’s base attaches to the margin of the glenoid fossa.  Outer surface attaches to the joint capsule superiorly and posteriorly  Inner surface is in the contact of head of humerus  It protects the joint and assists lubrication

Capsular Ligaments Glenohumeral ligament:  Superior glenohumeral ligament: It is splender shaped It arises from upper part of the glenoid labrum It runs laterally parallel to the biceps tendon to the upper tendon to the upper surface of the lesser tubercle

 Middle glenohumeral ligament: Arises from below the superior glenohumeral ligament Attaches to the humerus on the front of the lesser tubercle below the insertion of subscapularis

Inferior glenohumeral ligamrent: It is best developed of the three ligaments It arises from the anterior border of the glenoid labrum It descends slightly obliquely to the anteroinferior part of the anatomical neck The antero-superior edge of the inferior ligament is thickened and known as superior band The thickening of the anterior part of the capsule to which inferior ligament attaches is known as axillary pouch

Function of glenohumeral ligament:  They have no stabilizing function  Lateral rotation of the humerus put all three ligaments under tension  Medial rotation relaxes them  In abduction only the middle and inferior ligament become taut and superior ligament become relaxed

Transverse humeral ligament:  It is formed by some of the transeverse fibres of the capsule  At the upper end of the intertubercular groove, the transverse humeral ligamentbridges the gap between the greater and lesser tubercles.  It hold the biceps tendon in the intertubercular groove.

Intra- articular ligament These ligaments are considered as accessory ligament Coracohumeral ligament:  It is strong and broad  It arises from the lateral border of the coracoid process near its root.  It passes laterally above the intertubercular groove to attach to the anatomical neck to the greater and lesser tubercle  Anterior part of the ligament is free. But laterally it fuses with the tondon of subscapularis  It inserted in lesser tubercle

Coracoacromial ligament:  It is not directly associated with the joint  It is a strong and triangular ligament  It forms with the coracoid and acromion process, a fibro- osseous arch above the head of the humerus  Its anterior and posterior part is thicker than intermediate part.

Bursae between the subscapular tendon and articular capsule Sometimes between the infraspinatous tendon and capsule Subacromial bursa: between deltoid and capsule. On the superior acromial aspect Between coracoid process and capsule Sometimes behind coracobrachialis Between teres major and the long head of biceps

Muscle Deltoid (anterior fibre):  Origin: Arises from the anterior border and upper surface of the lateral third of the clavicle  Insertion:  Function:

Deltoid (middle fibres):  Origin: Arises from the lateral margin and upper surface of the acromion.  Insertion:  Function:

Deltoid (posterior fibre):  Origin: Arises from the lower lip of the posterior border of the spine of scapula, as far back as the triangular surface at its medial end.  Insertion:  Function:

Pectoralis major:  Origin:  Insertion;  Function:

Coracobrachialis:  Origin:  Insertion:  Function:

Biceps:  Origin:  Insertion:  Function:

Teres major:  origin:  Insertion  Function;

Latissimus dorsi:  Origin:  Insertion:  Function:

Supraspinatous:  Origin: Medial two-thirds of the supraspinatus fossa of scapula  Insertion: Superiorly of the greater tubercle of the humerus  Function:

Serratus anterior:  Origin: Originates on the surface of the upper eight ribs at the side of the chest and inserts along the entire anterior length of themedial border of the scapula  Insertion:  Function:

Trapezius:  Origin: Arises from theoccipital bone, the ligamentum nuchae, the spinous process of the seventh cervical, and the spinous processes of all the thoracic vertebrae  Insertion: It inserts on the lateral clavicle, the acromion process, and into the spine of the scapula.  Function:

Infraspinatous:  Origin: infraspinatus fossa just below the spine of the scapula  Insertion: Posteriorly on the greater tubercle of the humerus  Function:

Teres minor:  Origin: Posteriorly on the upper and middle aspect of the lateral border of the scapula  Insertion: Posteriorly on the greater tubercle of the humerus  Function:

Blood and nerve supply Artial supply: it is from numerous sources around the joint  Suprascapular branch of subclavian artery  Acromial branch of thoracoacromial artery  Anterior and posterior circumflex humeral arteries  Three are all branches of axillary artery

Venous drainage is by similarly named veins which drains into the external jugular and axillary veins Lymphetic drainage of the joint is to the lymph nodes within the axilla and passes into subclavian lymph trunk Nerve supply:  Suprascapular  Axillary]  Subscapular  Lateral pectoral  Musculocutaneous  Root value of C5,6 and7

Stability Factors responsible for stability:  The glenoid labrum- it deepening the glenoid fossa. And make the joint surface congurent  Rotator cuff- Most important factor Very close it the joint and fuse with lateral part of capsule. They act as ligaments Inferior part of capsule is weak and unsupported. But as the arm gradually abducted the long head of triceps and teres major support this

 Muscle of pectoral girdle and humerus: Long head of biceps: gives support over the superior part of joint Long head of triceps: gives support below the joint  Coracoacromial arch: it prevent upward displacement of the head of the humerus

Movement Flexion :  Flexion and extension occur about an axis prependicular to the plane of the glenoid fossa  In flexion the arm moves forward and medially at an angle of 45° to the sagital plane.  Range is 110°-180°  It is produced by the anterior fibres of deltoid, pectoralis major, coracobrachialis and biceps

Extension:  In extension arm moves backwords and laterally  Range is 70°-90°  Extension is limited by greater tubercle of the humerus coming into contact with the coracoacromial arch  Extension is produced by the posterior fibres of deltiod, teres major and latissimus dorsi

Abduction:  In abduction the arm moves anterolaterally away from the trunk  Total range is 120°  Only first 30° movement occurs without scapular rotation  The terminal part of the shoulder joint abduction is accompanied by lateral rotation of the humerusIt is due to provide further articular surface on the head of the humerus for the glenoid fossa  Abduction of the medially rotated humerus is limited by tension in the posterior capsule and lateral rotators

 First 20° abduction is initiated by supraspinatus muscle and deltoid continues the movement  If deltoid is paralysed, supraspinatus is not strong enough to fully abduct the shoulder.  If supraspinatous is not functioning, deltoid can not initiate abduction

Adduction:  In adduction the arm moves anteromedially  Adduction is produced by ecentric contraction of serratus snterior, trapezius, deltoid and supraspinatous

Rotation Rotation is limited by the extent of articular surface The range of rotation varies with the position of arm. It is greatest when the arm is by the side. Decreasing to 90° with the arm horizontal. And being negligible as the arm approaches vertical

Medial rotation:  Medial rotation causes the anterior surface of the humerus to be turned medially  The maximum range is 90°  Medial rotation is produced by subscapularis, pectoralis major, latissimus dorsi, teres major and anterior fibre of deltoid

Lateral rotation:  In lateral rotation the anterior surface of the humerus is turned laterally  The range is 80°  It is produced by infraspinatous, teres minor and posterior fibre of deltoid