Shoulder joint
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This document provides an overview of the kinesiology of the shoulder joint. It describes the anatomy of the shoulder joint including the glenohumeral joint and scapulothoracic joint. It details the motions of the shoulder in flexion, extension, abduction, adduction, internal and external rotation. The supporting structures of the shoulder including muscles like the rotator cuff and ligaments are outlined. Finally, the document examines the muscles involved in movements at the glenohumeral and scapulothoracic joints.
Shoulder joint
- 1. KINESOLOGY OF THE SHOULDER JOINT PRESENTED BY : DR.ASER MOHAMED KAMAL PHYSICAL THERAPY
- 2. SHOULDER joint • Glenohumeral joint • Articulation surface – between head of humerus and glenoid fossa of scapula • Ball and socket joint – allows 3 degrees of freedom • Flexion/extension, abduction/adduction, internal/external rotation, horizontal adduction/horizontal abduction • Shoulder abduction/adduction • Occur in the frontal plane/anteroposterior axis of rotation • Range of motion • - full abduction: 180 deg (120 shoulder abd + 60 deg scapular upward rotation) • - adduction : vice versa (120 shoulder add + 60 deg scapular downward rotation) • Involve the head of humerus rolling superiorly and slide inferiorly within glenoid fossa. • Without inferior slide, the humeral head stuck into the acromion ---- impingement (suprasapinatus tendon or subacromial bursa) Kinematics Shoulder flexion/extension • Occur in sagittal plane/medial-lateral axis of rotation • ROM - full flexion: 120 deg shoulder flexion + 60 deg scapular upward rotation - extension : reverse action of flexion + 40 – 60 deg of hyperextension
- 3. Shoulder internal/external rotation • Occur in horizontal plane/vertical axis of rotation • Rotation results in the anterior surface of humerus rotates medially/internally (internal rotation) or rotates laterally/externally (external rotation) • ROM - external rotation : about 90 deg (80-100 deg) - internal rotation : about 70 deg (65 – 80deg) Shoulder horizontal abduction/horizontal adduction • SPECIAL MOVEMENT • Occur when shoulder 90 deg abd, humerus will move in horizontal plane • Humerus move towards midline – horizontal adduction • Humerus move away form midline – horizontal abduction Supporting Structure • Shoulder joint – highly mobile (TRIAXIAL JOINT, LARGE ROM) but less stability • Due to large, rounded head of humerus and the shallowness of glenoid fossa of scapula • Strengthen by : 1. Rotator cuff muscles 2. Capsular ligaments 3. Coracohumeral ligament 4. Glenoid labrum 5. Long head of the biceps
- 4. ROTATOR CUFF MUSCLES • ROTATOR CUFF MUSCLES – CENTRE OF STABILITY • Consist of SITS; Supraspinatus, Infraspinatus, Teres minor and Subascapularis muscles • Function – centralizing and stabilizing the humeral head within glenoid fossa • Surround humeral head anteriorly, superiorly and posteriorly, and providing muscular force that pulls the humeral head towards glenoid fossa. Ligamentous Structure Capsular lig • Consist of superior, inferior and middle glenohumeral lig, attaches between the rim of gleoid gossa and anatomical neck of humerus Coracohumeral lig • Prevents inferior displacement of humeral head, prevent excessive motion of flexion, extension and external rotation, attaches between coracoid process of scapula and greater tubercle of humerus.
- 5. Others Structure Glenoid Labrum • A fibrocartilaginous riing that encircles the edge of glenoid fossa, deepen the glenoid fossa (nearly doubling the function of glenoid fossa) Long Head of the Biceps • The proximal portion of the tendon wraps around the superior aspect of the humeral head (originates form supraglenoid tubercle), provide anterior stability of shoulder joint. Palpation of Bony Landmarks of shoulder Scapula: 1. Spine – From AC joint palpate across the upper part of the posterior surface of the scapula. It is a long (3”) thin projection, which runs medial to lateral, at T3 level. 2. Acromion process – Located on the lateral part of the shoulder, right above the shoulder joint. 3. Coracoid process – Palpate under the lateral part of the clavicle (about one inch below the anterior edge of the clavicle). 4. Medial (vertebral) border – The edge of the scapula closest to the vertebral column (about 2 inches from the spinous processes). The medial border runs in a superior-inferior direction. 5. Lateral (axillary) border – The lateral (or outer) edge of the scapula located between the inferior angle and the shoulder joint. 6. Superior medial angle – Located above the vertebral border or medial aspect of scapula, level T2. 7. Inferior angle – Located between vertebral and axillary borders. The “point” at the bottom of scapula, level T7.
- 6. Clavicle: “Collar bone” – anterior from sternum to acromion Humerus: 1. Greater tuberosity – Located just below acromion when arm is resting by the side. (proximal end of humerus) 2. Lesser tuberosity – Easiest to palpate with arm in shoulder external rotation. Located medial to greater tuberosity on proximal end of humerus. 3. Intertubercular (Bicipital) Grove – Located between greater and lesser tuberosity; easiest to palpate with arm in external rotation. 4. Medial and lateral epicondyles – Palpated on medial and lateral sides, respectively, of distal end of humerus (2 “bumps” on distal end). 5. Medial and lateral supracondylar ridge – above the medial and lateral epicondyles on distal end of humerus. 6. Olecxranon fossa – indentation on posterior of elbow Scapulohumeral Rhythm • The full range of shoulder motion normally is combination between the motion in glenohumeral and scapulothoracic joint. • A natural rhythm/ratio between GH joint and scapulothoracic joint --- 2:1 • That’s means for every 2 deg of shoulder abduction/flexion, the scapula must upward rotate roughly 1 deg. (vice versa for adduction/extension) • The full ROM of shoulder abduction/flexion= 180 deg, which combination between 120 deg shoulder abduction/flexion + 60 deg scapular upward rotation. 180 degrees of shoulder abduction/flexion = 120 degrees of glenohumeral joint abduction + 60 degrees of scapulothoracic joint upward rotation
- 7. Scapulothoracic (ST) Joint • Not a truth joint • Articulating between anterior surface of scapula to posterior thorax (ribs 2-7) • Movements : permits scapular elevation/depression, protraction/retraction, upward/downward rotation • Motion of ST joint is dependent on the combined movement of the acromioclavicular (AC) and sternoclavicular (SC) joint. • The full 60 deg ST joint upward rotation = 30 deg of SC joint elevation + 30 deg AC joint upward rotation THE RELATIONSHIP BETWEEN AC, SC, ST AND GH JOINTS MOTIONS. 180 degrees of shoulder abduction/flexion = 120 degrees of GHJ abduction + 60 degrees of STJ upward rotation 60 degrees STJ upward rotation = 30 degrees of SCJ elevation + 30 degrees of ACJ upward rotation SCAPULOTHORACIC JOINT MUSCLES Primary Elevators of ST joint Primary Depressor of ST joint - Upper fiber of trapezius - Lower fiber of trapezius - Levator scapulae - Latissimus dorsi - Rhomboids
- 8. Upper / Superior Fiber of Trapezius • Origin – medial one third of the superior nuchal line, external occipital protuberance and ligamentum nuchae. • Insertion – posterior border of the lateral one third of the clavicle. • Action – scapular elevation Levator Scapulae • Origin – transverse process of Superior four or five cervical vertebrae. • Insertion – superior vertebral border of scapula • Action – Elevates scapula and rotates it downward. • Nerve supply – dorsal scapular nerve and cervical spinal nerve Rhomboid Major • Origin – Spine of 2nd to 5th thoracic vertebrae • Insertion – vertebral border of scapula inferior to spine of scapula • Action – elevates and adducts scapula and rotate it downward; stabilize scapula • Nerve – dorsal scapular nerve
- 9. Rhomboid Minor • Origin – Spine of 7th cervical and 1st thoracic vertebrae. • Insertion – Vertebrae border of scapula superior to spine • Action – elevates and adducts scapula and rotate it downward; stabilize scapula • Nerve – dorsal scapular nerve Lower / Inferior Fiber of Trapezius • Origin – spinous process of T6-T12 • Insertion – spine of the scapula • Action scapular depression and adduction Latissimus Dorsi • Origin – Spines of inferior 6 thoracic vertebrae (T6-T12), lumbar vertebrae (L1- L5), crest of sacrum and illiac crest of hip bone, inferior four ribs and inferior angle of scapula. • Insertion – Intertubecular sulcus of humerus • Action – Extends, adduction and medial rotation arm at shoulder joint. • Nerve supply - Thoracodorsal nerve
- 10. SCAPULOTHORACIC JOINT MUSCLES Primary upwards rotators of ST joint • Upper fiber of trapezius • Lower fiber of trapezius • Serratus anterior Primary downward rotators of ST joint • Rhomboids • Pectoralis minor Serratus Anterior • Origin – Superior 8 or 9 ribs • Insertion – vertebral border and inferior angle of scapula • Action – Abduction and rotates the scapula upward – Elevate ribs when scapula stabilized. – Also known as “boxer’s muscles” • Nerve supply – Long thoracic nerve Pectoralis Minor • Origin – 2nd - 5th ribs, 3rd – 5th ribs or 2nd – 4th ribs. • Insertion – Coracoid process of scapula
- 11. • Action – Abduction scapula and rotates it downward – Elevate the ribs during forced inhalation. • Nerve supply – Medial pectoral nerve SCAPULOTHORACIC JOINT MUSCLES Primary protractors of ST joint • Serratus anterior Primary retractors of ST joint • Rhomboids • Middle fiber of trapezius Middle Fiber of Trapezius • Origin – spinous process of T1 – T5 • Insertion – medial border of the acromion process of scapula, and superior border of the spine of the scapula. • Action – scapular adduction. Glenohumeral Joint Muscles Primary GH Joint Abductors • Anterior fiber of deltoid • Middle fiber of deltoid • Supraspinatus Primary GH Joint Adductors • Latissimus dorsi • Teres major • Pectoralis major (sternal head)
- 12. Anterior Fiber of Deltoid • Origin – anterior border of the lateral one third of the clavicle • Insertion – deltoid tuberosity • Action – abduction, flexion and middle rotation arm at GH joint. Middle fiber of Deltoid • Origin – lateral border and superior surface of the acromion process of the scapula • Insertion – deltoid tuberosity • Action – abduction arm at GH joint Supraspinatus Muscle • Origin – supraspinous fossa of scapula • Insertion – Greater tubercle of humerus (anterior aspect) • Action – initially abduction (15 degrees) at shoulder joint, stabilizing shoulder joint • Nerve supply - Suprascapular nerve Sternal origin of Pectoralis Major • Origin – anterior surface of sternum, costal cartilage of 2nd -6th ribs. • Insertion – greater tubercle and intertubercular sulcus of humerus • Action – extend arm at shoulder joint. • Nerve supply – Medial and lateral pectoral nerve
- 13. Teres Major • Origin – Inferior angle of scapula • Insertion – Intertubecular sulcus of humerus • Action – Extends arm at shoulder joint – Assist in adduction and medial rotation of arm at shoulder joint. • Nerve supply – Lower subscapular nerve Glenohumeral Joint Muscles Primary GH Joint Flexors • Anterior fiber of deltoid • Pectoralis major (clavicular head) • Coracobrachialis • Biceps brachii Primary GH Joint Extensors • Latissimus dorsi • Teres major • Pectoralis major (sternal head) • Posterior deltoid • Long head of triceps
- 14. Clavicle origin of Pectoralis Major • Origin – medial half of anterior clavicle • Insertion – greater tubercle and intertubercular sulcus of humerus • Action – Flexion, adduction and medial rotation arm at shoulder joint. • Nerve supply – Medial and lateral pectoral nerve Coracobrachialis • Origin - Coracoid process of scapula • Insertion - Middle of medial surface of shaft of humerus. • Action - Flexion and adduction arm at shoulder joint. • Nerve supply - Musculocutaneous nerve Short head of Biceps • Origin – Coracoid process of scapula • Insertion – radial tuberosity of radius • Action – Flexion forearm at elbow joint, flexion arm at GH joint and supination at radioulnar joint. • Nerve supply - Musculocutaneous nerve Long head of Biceps • Origin – Tubercle above the glenoid cavity of scapula (supraglenoid tubercle) • Insertion – Radial tuberosity of radius • Action – flexion forearm at elbow joint, flexion arm at GH joint and supination forearm at radioulnar joint. • Nerve supply - Musculocutaneous nerve
- 15. Posterior Fiber of Deltoid • Origin – inferior lip of the crest of the spine of the scapula • Insertion – deltoid tuberosity • Action – extension and lateral rotation arm at GH joint. Long head of Triceps • Origin – tubercle below to glenoid cavity of scapula (infraglenoid tubercle) • Insertion – Olecranon of ulna • Action - Extends forearm at elbow joint , Extends arm at shoulder joint • Nerve supply - Radial nerve Glenohumeral Joint Muscles Primary GH Joint Internal Rotators • Anterior fiber of deltoid • Pectoralis major • Latissimus dorsi • Teres major • Subscapularis Primary GH Joint External Rotators • Posterior deltoid • infraspinatus • Teres minor Infraspinatus Muscle • Origin – Infraspinous fossa of scapula • Insertion – Greater tubercle of humerus (posterior aspect) • Action – Laterally rotation and adduction arm at shoulder joint • Nerve supply - Suprascapular nerve
- 16. Teres Minor • Origin – Inferior lateral border of scapula • Insertion – Greater tubercle of humerus (inferior aspect) • Action – Laterally rotation, extends and adduction arm at shoulder joint • Nerve supply – axillary nerve Subscapularis Muscle • Origin – subscapular fossa of scapula • Insertion – lesser tubercle of humerus • Action – Medial rotation arm at shoulder joint • Nerve supply – upper and lower subscapular nerve