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Kinesiology Chapter 5 a

Kinesiology Chapter 5 a - Chapter 5 The Upper Extremity The...

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Unformatted text preview: Chapter 5: The Upper Extremity: The Shoulder Region The Joints: SC Joint: SC AC Joint AC GH Joint ??? Joint (False Joint) Degrees of Freedom: 1,2,3 Degrees 1: Flexion and Extension: knee 2: Radial and Ulnar Deviation & Flexion and Extension: wrist 3: ???? Movements of Joint Surfaces or Accessory Motions: See Figure Accessory Rolling/rocking Sliding/gliding Spinning Kinematics: the science of the motion of bodies in space motion Osteokinematics Arthrokinematics Convex vs Concave Rule of Kinematics: See Figure Kinematics: Concave on convex Convex on concave Close-packed and Open-packed Positions Positions Close-packed: Max surface area contact at joint Ligament attach. Are far apart Ligament and tense and Capsule is taut Joint is compressed Open-packed: All other positions JOINT CLOSE PACK OPEN PACK SC JOINT ELEVATION AND PROTRACTION ARM BY SIDE AC JOINT FULL SHOULDER ELEVATION ARM BY SIDE GLENOHUMERAL JOINT 90 DEGREES OF ABDUCTION AND ER 55 DEGREES OF ABDUCTION, 30 DEGREES HORIZONTAL ADD, 0 DEGREES OF ROTATION RATIO OF THE SCAPULOHUMERAL RHYTHM SCAPULOHUMERAL Scapulohumeral Rhythm Scapulohumeral Scapula rotates 1 degree for every 2 degrees movement of the humerus Allows increased range of motion at the glenohumeral joint. SCAPULOHUMERAL RHYTHM SCAPULOHUMERAL Shoulder elevation involves: – humeral movement (at glenohumeral joint) – scapular movement (at scapulothoracic joint) Scapulohumeral rhythm: (describes the timing of movement at these joints during shoulder elevation.) first 30 degrees of shoulder elevation involves a "setting phase": – The movement is largely glenohumeral. – Scapulothoracic movement is small and inconsistent. after the first 30 degrees of shoulder elevation: – The glenohumeral and scapulothoracic joints move simultaneously. – Overall 2:1 ratio of glenohumeral to scapulothoracic movement. SCAPULOHUMERAL RHYTHM SCAPULOHUMERAL You can observe scapulohumeral rhythm by palpating the scapula's position as a person elevates the shoulder. Helpful scapular landmarks for palpation are the base of the spine and the inferior angle. Scapulohumeral rhythm serves at least two purposes. – It preserves the length­tension relationships of the glenohumeral muscles; the muscles do not shorten as much as they would without the scapula's upward rotation, and so can sustain their force production through a larger portion of the range of motion. – It prevents impingement between the humerus and the acromion. Because of the difference in size between the glenoid fossa and the humeral head, subacromial impingement can occur unless relative movement between the humerus and scapula is limited. Simultaneous movement of the humerus and scapula during shoulder elevation limits relative (arthrokinematic) movement between the two bones. SC Joint: Importance? Importance? Raise arm overhead, what does it Raise do? do? Movements: Movements: Elevation, depression, Elevation, Protraction, retraction, Rotation AC joint: ER with abduction and FF What moves more: AC vs SC? Scapula: Scapula: Movements: What are they? Musculature: Review of Figures Functions of the Muscles Pectoral Minor: inspiration, chest posture Serratus Anterior: works with LT for humeral elevation Trapezius: four parts: see figure Scapular Stabilizers: What are they? Subscapularis: depresses the humeral head during abd/flex; prevents dislocation during forced ER of abducted arm Supraspinatus: prevents downward dislocation Subscap/Infraspinatus/Teres Minor: depress the head of the humerus and prevent impingement Shoulder Joint: Favors mobility vs stability vs Posture: How does posture Posture: effect the shoulder upper quarter positioning and above shoulder activities? activities? Common Shoulder Pathology Impingement (can lead to bursitis, tendonitis of LHB, RC, AC DJD, RCT or strain) Dislocation of the shoulder •Subcoracoid: common •Subglenoid •Posterior dislocation Multi­positional instability (young athletes) RC strain: Supraspinatus tough to heal…why? Frozen Shoulder: adhesive capsulitis ...
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