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The shoulder joint


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Anatomy of Shoulder Joint

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The shoulder joint

  1. 1. The Shoulder Joint By : Gan Quan Fu, PT, MSc. Human Anatomy (Batch 3)
  2. 2. Content • Introduction • Glenoid Cavity • Ligaments Surrounding the joint • Bursae in Relation to the Shoulder Joint • Muscles Acting on Shoulder Joint • Blood and Nerve Supply • Joint Movement • Close and Loose Pack Position • Applied Anatomy
  3. 3. Overview
  4. 4. Introduction • Enarthrodial or Ball-and-Socket joint • Bones Involve o Large globular head of humerus o Glenoid cavity of scapula • Protected against displacement by tendons and by atmospheric pressure. • Ligaments around gleno-humeral joint; Limit the amount of joint movement o Capsular o Coracohumeral o Transverse Humeral o Glenoid Ligament • Above protected by arched vault formed by: o Under surface of coracoid process o Under surface of acromion process o Coraco-acromial ligament
  5. 5. Glenoid Cavity • Pear Shape • Shallow • Directed Laterally and Upward • Only1/3rd of the humeral head comes in contact with the glenoid cavity at any position. • Glenoid Fossa is deepened by a fibro- cartilaginous rim of Glenoid labrum.
  7. 7. Capsular Ligament • Encircles entire glenohumeral joint. • Attached: o Medially: Above to the circumference of glenoid cavity beyond the glenoid ligament o Laterally: Below to anatomical neck of the humerus • Thicker above and below. • Loose and lax • Allow bone to be separated from each other more than an inch
  8. 8. Muscles Supporting Capsular Ligament • Superiorly  Supraspinatus • Inferiorly  Long Head of Triceps • Posteriorly  Tendons of Infraspinatus and Teres Minor • Anteriorly  Tendon of Subscapularis
  9. 9. Openings of Capsular Ligament 3 Openings o Anteriorly • Below coracoid Process, connection between synovial membrane of the joint and a bursa beneath the tendon of subscapularis muscle. • Between the 2 tuberosities, passage of the biceps long head. o Posteriorly • Not constant, where a communication exists between joint and a bursal sac belonging to Infraspinatus muscle.
  10. 10. Supplemental Bands of Capsular Ligament • Strengthen capsular ligament in the interior of the joint. • Flood’s Ligaments o Situated on inner side of joint o Passes from inner edge of glenoid cavity o Attached to lower part of lesser tuberosity of humerus. • Schlemm’s Ligaments o Situated at lower part of the joint o Passes from under edge of glenoid cavity o Attached to under part of neck of humerus • Glenohumeral Ligaments o Situated at upper part of the joints, projects into its interior (can only be seen when capsule is open). Attached above apex of glenoid cavity close to root of coracoid process, attached below lesser tuberosity of humerus (Forms inner boundary of upper part of bicipital groove)
  11. 11. Glenohumeral Ligaments • 3 fibrous bands derived from thickening of the anterior part of fibrous capsule. • All 3 Converge upward and medially blend with glenoid labrum: o SUPERIOR BAND : attached to the upper end of lesser tubercle o MIDDLE BAND : attached to lower part of lesser tubercle o INFERIOR BAND : lower part of anatomical neck of humerus.
  12. 12. CORACO-HUMERAL LIGAMENT • Broad Thick Band • Strengthens Upper part of Capsular Ligament • Attachments o Arises from outer border of coracoid process o Blended with tendon of supraspinatus muscles • United to capsule in greater part of its extend.
  13. 13. TRANSVERSE HUMERAL LIGAMENT • Broad band of fibrous tissues • Connects the two lips of the upper part of intertubercular sulcus and acts as a retinaculum to keep the long tendon of biceps in position.
  14. 14. GLENOID LABRUM • Fibro-cartilage rim attached around margin of glenoid cavity. • Triangular on section • Thickest portion at circumference of cavity, free edge is sharp and thin • Continuous above with long head of biceps • Deepens cavity for articulation and protects edges of bone • Lined by synovial membrane
  15. 15. SYNOVIAL MEMBRANE • Reflected from margin of glenoid cavity over fibro- cartilaginous rim surrounding it. • Over internal surface of capsular ligaments. • Covers lower part and sides of anatomical neck of humerus.
  17. 17. BURSA • SUBSCAPULAR BURSA Intervenes between the tendon of subscapularis and fibrous capsule. Communicates with the joint cavity through oval gap between superior and middle glenohumeral ligaments. • Infraspinatus bursa Communicates with the joint from behind • Subacromial bursa Largest bursa of the body intervenes between supraspinatus and coraco- acromial arch. It does not communicate with the joint. It is of great value in the abduction of arm at the shoulder joint where is protects the supraspinatus tendon against friction with the acromion
  18. 18. Muscles in Relation to the Joint • Above  Supraspinatus • Below  Long head of Triceps • Front  Subscapularis • Behind  Infraspinatus and Teres Minor • Deltoid is placed most externally and covers the articulation from its outer side, as well as in front and behind.
  19. 19. Blood and Nerve Supply • Blood Supply 1.Anterior circumflex humeral vessels 2.Posterior circumflex humeral vessels 3.Suprascapular vessels • NERVE SUPPLY 1) Axillary nerve 2) Musculocutaneous nerve 3) Suprascapular Nerve 4) Lateral pectoral nerve
  20. 20. Summary on Should Joint Anatomy
  21. 21. MOVEMENTS AT THE SHOULDER JOINTS • Movement in every direction (Flexion, extension, abduction, adduction, rotation, circumduction) • Highly mobile due to: o Large size of head of humerus in comparison with the depth of glenoid cavity (Even when supplemented by glenoid ligament) o Looseness of the capsule of the joint (Laxity of fibrous capsule) o When movements of arm are arrested by contact of the bony surface  Tension of corresponding fibers and muscles acting on accessory ligaments farther movements of scapula and accessory structures to the shoulder joint (acromio and sterno- clavicular joints). • Spinal Cord regulating Shoulder movements (C5, C6, C7 & C8) o Flexion, Abduction, & lateral rotation (C5, C6,). o Extension, Adduction, & Medial rotation is (C6, C7, C8)
  22. 22. Osteo- & Arthrokinematics of Shoulder Joint • Osteokinematics o Flexion o Extension o Hyperextension o Abduction o Adduction o Medial rotation (internal rotation) o Lateral rotation (external rotation) o Horizontal abduction o Horizontal adduction o Circumduction • Concave-convex rule o Convex humeral head moves within the concave glenoid fossa o The Convex joint surface (Humeral Head) moves in a direction opposite to the movement of the body segment (Humeral Shaft)
  23. 23. Flexion • Plane of Motion: o Sagittal Plane • Axis of Motion: o Transverse Axis through the center of the humeral head • Muscles Involved: o Pectoris major o Anterior Fibres od Deltoid o Coraco-brachialis o Biceps (When the foreare is flexed) • Humeral head glides posterior laterally in the glenoid cavity • Range of Motion o 0 – 90 degrees
  24. 24. Factors Limiting Shoulder Flexion • Inferior Glenohumeral ligament • Tightness of posterior joint capsule
  25. 25. Extension • Plane of Motion: o Sagittal Plane • Axis of Motion: o Transverse Axis through the center of the humeral head • Muscles Involve: o Latissimus dorsi o Teres major o Posterior fibers of Deltoid o Triceps (When forearm is extended) • Humeral head glide anterior medially in glenoid cavity • Range of Motion o 0 – 45 degrees or 60 degrees
  26. 26. Factors Limiting Shoulder Extension • Superior and medial gleno-humeral ligament
  27. 27. Abduction • Plane of Motion: o Frontal Plane • Axis of Motion: o Sagittal axis through the center of the humeral head • Muscles Involve: o Deltoid o Supraspinatus • Humeral head glide inferiorly in glenoid cavity • Range of Motion o Total : 0 – 165 degrees or 175 degrees o Full internal rotation of humerus: 0 – 60 degrees o Full external rotation of Humerus: 0 – 90 degrees
  28. 28. Factors Limiting Shoulder Abduction • Inferior glenohumeral ligament • Tightness of the inferior joint capsule of the glenoumeral joint
  29. 29. Adduction • Plane of Motion: o Frontal Plane • Axis of Motion: o Sagittal axis through the center of the humeral head • Muscles Involve: o Subscapularis o Pectoralis Major o Latissimus dorsi o Teres major • Humeral head glide superiorly in glenoid cavity • Factors Limiting: o Trunk
  30. 30. Internal Rotation • Plane of Motion: o Transverse Plane • Axis of Motion: o Vertical axis through the center of humeral head • Muscles Involve: o Subscapularis o Pectoralis Major o Latissimus dorsi o Teres major • Humeral head glide posteriorlaterally in glenoid cavity • Range of Motion o 0-70º as the arm at 90º of shoulder abduction and 90º elbow flexion o If the elbow is extended, shoulder rotation occurs simultaneously with forearm rotation.
  31. 31. Factors Limiting Internal Rotation • Posterior Capsule
  32. 32. External Rotation • Plane of Motion: o Transverse Plane • Axis of Motion: o Vertical axis through the center of humeral head • Muscles Involve: o Infraspinatus o Teres Minor • Humeral head glide anteriomedially in glenoid cavity • Range of Motion o 0-90º as the arm at 90º of shoulder abduction and 90º elbow flexion o If the elbow is extended, shoulder rotation occurs simultaneously with forearm rotation.
  33. 33. Factors Limiting External Rotation • Coracohumeral ligament • 3 glenohumeral ligaments
  34. 34. Circumduction • A combination of flexion, abduction, extension, and adduction or in the reversed sequence o glenohumeral flexion  abduction  extension  adduction o glenohumeral extension  abduction  flexion  adduction
  35. 35. Close and Loose Packed Position • Close Packed position o Position where the articular surfaces of joint are in maximal congruency status, resulting in greatest mechanical stability. o Most ligament and capsule surrounding joint are taut. o 90° of glenohumeral abduction and full external rotation • Loose Packed position o Position where the articular surface of joint are in minimal congruency status. o Supporting structures are most lax. o 55° of semi-abduction and 30° of horizontal adduction
  36. 36. Dislocation • Humeral head is hold in place by the Rotator cuff (S,I,T,S) Muscles. • Humeral Head separated from scapula at glenohumeral joint. • Commonly downward dislocation because Rotator Cuff protects joints in all direction except inferiorly. • Hemiparesis/Hemiplegia patients prone to dislocate their shoulder  their Rotator cuff muscles are weak to hold the shoulder joint in place.
  37. 37. Adhesive Capsulitis • Frozen Shoulder • Pain and Stiffness in the Shoulder • Shoulder capsule thickens and becomes tight. Stiff bands of tissue — called adhesions — develop. In many cases, there is less synovial fluid in the joint. • Unable to move your shoulder - either on your own or with the help of someone else.
  38. 38. Stages of Adhesive Capsulitis • It develops in three stages: o Freezing (Pain worsens, shoulder loses range of motion. Typically lasts from 6 weeks to 9 months.) o Frozen (Painful symptoms may actually improve during this stage, but the stiffness remains. During the 4 to 6 months of the "frozen" stage, daily activities may be very difficult.) o Thawing (Shoulder motion slowly improves. Complete return to normal or close to normal strength and motion. Typically takes from 6 months to 2 years.)
  39. 39. SLAP LESION • Injury to the labrum of the shoulder. • SLAP = Superior Labrum Anterior and Posterior. • In a SLAP injury, the superior part of the labrum is injured. This top area is also where the biceps tendon attaches to the labrum. • SLAP tear occurs both in front (anterior) and back (posterior) of this attachment point. • The biceps tendon can be involved in the injury as well.
  40. 40. Bankart Lesion • Tear of the labrum and attached joint capsule along the anterior inferior quadrant of the Glenoid ligament/Inferior glenohumeral ligament. • Associated with shoulder dislocation. • Bony Bankart is when some of the glenoid bone is broken off with the anterior inferior labrum (Shoulder joint more unstable than Bankart Tear)
  41. 41. Shoulder Bursitis • Inflammation of shoulder Bursa • Commonly Subacromion Bursa o Usually related to shoulder impingement of Subacromion Bursa between rotator cuff tendon and acromion • Subdeltoid bursa less commonly inflammed • Commonly co-exists with rotator cuff tears or tendonitis
  42. 42. Surgical Intervention • Front of the shoulder joint is commonly approached for surgical intervention • Aspiration needle maybe introduced through deltopectoral triangle (closer to deltoid)
  43. 43. References • Gray, H. (2012) Gray’s Anatomy; The classic Anatomical Handbook for Doctors, Students and Artist, 15th edn. London; Bounty Books. • Saladin, K. S. (2007) Anatomy and Physiology: The Unity of Form and Function. 4th edn. New York; McGraw-Hill.