5 - Shoulder 1

5 - Shoulder 1 - Foundations of Occupation: Occupation:...

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Unformatted text preview: Foundations of Occupation: Occupation: Kinesiology Shoulder Complex – Part 1 Lecture 5 Summer 2010 ¡Fiesta! Overview Overview • Anatomical Review of Shoulder Complex – bones, joints • Motions of the Shoulder Girdle and Motions Glenohumeral Joint Glenohumeral • Scapulohumeral Rhythm Scapulohumeral • Muscles of the Shoulder Girdle • Muscle Synergies at the Shoulder Girdle Clarification of Terms Clarification • Shoulder Complex - usually includes all the structures involved in shoulder motion structures – includes scapula, clavicle, sternum, humerus, rib cage Sternoclavicular, – Sternoclavicular, acromioclavicular, glenohumeral joints – scapulothoracic articulation • Shoulder Girdle - scapula, clavicle, sternum • Shoulder Joint (Glenohumeral joint) - scapula, humerus humerus Shoulder Shoulder Complex Shoulder Shoulder Girdle Function of the Scapula Function • Orient the glenoid fossa Orient for maximal use of UE for • Provide a stable base Provide for ball and socket movements of glenohumeral joint glenohumeral • Scapula and Scapula glenohumeral joint are always discussed together together Anatomic Review Anatomic Review Scapula: Dorsal Aspect Scapula: • Dorsal Aspect – – – – – – – – – – – Superior border Medial border Lateral border Superior angle Inferior angle Supraspinous fossa Infraspinous fossa Glenoid cavity Spine Acromion Coracoid Scapula: Ventral Aspect Scapula: Ventral Aspect – subscapular fossa – coracoid process (better view since it protrudes anteriorly) – glenoid fossa Scapula: Lateral Aspect Scapula: Lateral Aspect – acromion – coracoid process – glenoid fossa Clavicle and Sternum Clavicle • Clavicle – acromial end – sternal end – anterior and posterior border • Sternum – manubrium – body – Xiphoid Humerus Humerus • • • • • • Head of Humerus Anatomical neck Surgical neck Greater tubercle Lesser tubercle Bicipital or intertubercular groove Joints of the Joints of the Shoulder Complex Sternoclavicular joint Acromioclavicular joint Scapulothoracic articulation (not a true joint) Glenohumeral joint Sternoclavicular Joint Sternoclavicular • Plane synovial joint - three degrees of Plane freedom freedom disc disc • Joint capsule, 3 major ligaments and joint Joint • Ligaments: Anterior – Anterior and posterior sternoclavicular ligaments reinforce joint capsule reinforce Costoclavicular – Costoclavicular ligament - located between first rib and clavicle rib Interclavicular – Interclavicular ligament - runs from the sternal end of one clavicle to the sternal end of the other end Sternoclavicular Joint Sternoclavicular Joint Acromioclavicular Joint Acromioclavicular • Primarily maintains relationship between the scapula and Primarily clavicle clavicle dentified • IIdentified as a gliding or plane joint; 3 degrees of freedom freedom • Produces longitudinal rotation of clavicle necessary for Produces • • full ROM and elevation of UE full Joint capsule Ligaments: Superior – Superior and Inferior Acromioclavicular Ligaments – maintain relationship between clavicle and scapula relationship Corcoclavicular – Corcoclavicular Ligament – provides stability; prevents superior dislocation of clavicle dislocation Coracoacromial – Coracoacromial Ligament – provides support to head of humerus humerus Acromioclavicular Joint Acromioclavicular Scapulothoracic Articulation • Not a true anatomic joint (does not have true characteristics) • Maintains a direct relationship of scapula to the thorax Glenohumeral Joint Glenohumeral • Articulation of head of Articulation humerus and glenoid fossa fossa • Glenoid fossa • Glenoid labrum • Joint capsule of Joint glenohumeral joint glenohumeral Glenohumeral Joint (cont’d) Glenohumeral Joint (cont’d) • Subacromial bursa • Visual of bursa • Ligaments: – Glenohumeral Ligaments (3) – reinforce capsule Coracohumeral – Coracohumeral Ligament – passive support of UE versus gravity versus Coracoacromial – Coracoacromial Arch – acromion + coracoacromial ligament…prevents superior dislocation ligament…prevents coracoid Know Your Ligaments…Review Know Your Ligaments…Review • 1. Sternoclavicular Joint – Anterior & posterior sternoclavicular ligaments – Costoclavicular ligament – Interclavicular ligament • 3. Scapulothoracic articulation – No ligaments (not a true joint) • 2. Acromioclavicular joint – Superior & inferior acromioclavicular ligaments – Coracoclavicular ligament – Coracoacromial ligament • 4. Glenohumeral joint – (3) glenohumeral ligaments – Coracohumeral ligament – Coracoacromial arch (acromion & coracoacromial ligament Shoulder Girdle Movements Movements • • • • • • • Elevation Depression ABduction / protraction ADduction / retraction Upward rotation Downward rotation Upward lift/Lateral tilt • Glenohumeral Movements Scapular Elevation & Scapular Elevation & Depression Scapular Abduction & Adduction Scapular Abduction & Adduction (protraction & retraction) Scapular Upward Rotation & Scapular Upward Rotation & Downward Rotation Scapular Upward Lift/Lateral Tilt Scapular Upward Lift/Lateral Tilt Glenohumeral Joint Movements Glenohumeral Joint Movements • Flexion / Extension ­ sagittal plane, X axis – depends on amount of scapular rotation • Abduction / Adduction ­ frontal plane, Z axis – depends on amount of scapular rotation – influenced by position of humerus • External / Internal Rotation ­ horizontal plane, Y axis Adduction • Horizontal Abduction / Scapulohumeral Rhythm Scapulohumeral Rhythm • Humerus must act in a coordinated way with the scapula to provide smooth and full range of motion without impingement. • 180 degrees of “shoulder flexion/aBduction” = – 120 degrees of glenohumeral motion – 60 degrees of scapular motion Purposes of Scapulohumeral Rhythm Purposes • Maintain glenoid fossa in optimal position to Maintain receive head of humerus; increasing joint congruency and decreasing shear forces congruency • Distributes motion between two joints permitting Distributes a larger ROM with more stability larger • Permits muscles acting on humerus to maintain Permits a good length-tension relationship good Scapulohumeral Rhythm : Phase One Phase • First 30 degrees of Scapulothoracic (ST) Motion ­ scapular upward rotation – occurs at: – Sternoclavicular (SC) joint with 25 degrees of elevation of lateral end of clavicle – Acromioclavicular (AC) joint with 5 degrees of upward rotation of the scapula – Serratus anterior and traps 2 and 4 initiate upward rotation of scapula, which elevates clavicle – Acromioclavicular ligament is taut allowing for constant relationship between clavicle and scapula – Lateral end of clavicle elevates 25 degrees – Costoclavicular ligament becomes taut, limiting clavicular elevation – Scapula upwardly rotates 5 degrees at AC joint until coracoclavicular ligament becomes taut • Sequence: • Primary arc of motion has its axis at base of spine of scapula • 30 degrees of ST motion is accompanied by 60 degrees of GH motion • Arm raised to 90 ­100 degrees Scapulohumeral Rhythm : Phase Two Phase • Last 30 degrees of Scapulothoracic Motion ­ scapular upward rotation – occurs at: – Acromioclavicular (AC) joint with 25 degrees of upward rotation of the scapula – Sternoclavicular (SC) joint with 5 degrees of elevation of lateral end of clavicle – Scapular upward rotators continue to pull – Coracoclavicular ligament becomes taut, causing rotation of clavicle, anterior border flips up and back, becoming superiorly positioned – Clavicle and scapula now free to complete upward rotation (above) • Sequence: • Scapula upwardly rotates the final 30 degrees • Primary axis of rotation is at the acromioclavicular joint • Raising arm from horizontal to vertical position involves an additional 30 degrees of scapular upward rotation AND 60 degrees of glenohumeral motion Scapulohumeral Rhythm Summarized Scapulohumeral Phase One: Accepting 180 degrees as maximal range of flexion and aBduction of humerus, raising arm to horizontal involves 60 degrees of GH motion and 30 degrees of ST motion. Scapular motion is composed of 25 degrees clavicular elevation at SC jt, and 5 degrees upward rotation at the AC joint. Phase Two: Raising arm from horizontal to vertical involves an additional 60 degrees of GH motion and 30 degrees of scapular motion allowed by clavicular rotation composed of 5 degrees clavicular elevation at SC joint, and 25 degrees upward rotation at AC joint. Clinical Implications • Shoulder cannot fully flex/aBd without scapulothoracic (ST) motion! • Attempting ROM without movement at ST articulation will cause damage… • Damage @ sternoclavicular (SC) ligament/joint ­> clavicle cannot elevate ­> limited shoulder motion will not rotate ­> limited shoulder motion • Damage @ coracoclavicular ligament ­> clavicle Muscles of Shoulder Girdle/Prime Movers for Scapular Motions: Movers • Anterior Muscles – Serratus Anterior – Pectoralis Minor • Posterior Muscles – Trapezius – Rhomboids – Levator Scapulae Muscles of Scapula / Shoulder Girdle Muscles Serratus Anterior Pectoralis Minor Trapezius 1 Trapezius 2 Trapezius 3 Trapezius 4 Rhomboids Levator Scapulae Abduction Upward Rotation Depression, Abduction Downward Rotation Elevation Elevation, Upward Rotation Adduction Depression, Upward Rotation Elevation, Adduction Downward Rotation Elevation Posterior Posterior Posterior Anterior Anterior Scapula Prime Movers by Motion Scapula Scap. Abduction: Serratus Anterior, Pec Minor Scap. Adduction: Trap III, Rhomboids Scap. Depression: Pectoralis Minor, Trap IV Scap. Elevation: Trap I, II, Levator Scap., Rhomboids Scap. Downward Rotation: Pec Minor, Rhomboids Scap. Upward Rotation: Trap II, IV, Serratus Anterior Muscle Synergies at the Muscle Synergies at the Shoulder Girdle • Agonists • Neutralizing synergists • Antagonists • Stabilizing synergists (fixators) Agonists Agonists • Agonists: Scapular Abductors – Scapular aBductors: – Scapular aDductors: – Scapular depression: – Scapular elevators: – Scapular downward rotators: – Scapular upward rotators: Neutralizing Synergists Neutralizing Synergists • Neutralizing Synergists: – Scapular Upward Rotators: – Scapular Adductors: Antagonists Antagonists • Some muscles act solely as antagonists • Example: – Scapular aBduction & aDduction • If both muscles contract simultaneously and with equal force… Stabilizing synergists Stabilizing synergists • Stops unwanted movements… • Stabilizing Synergists (fixator): – During shoulder abduction, ______________ & ___________________hold scapula in aDduction ...
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