Biomechanics of Human Upper Extremity ENT 214 Biomechanics Biomechanics of Human Upper Extremity Picture retrieved from http://catalog.nucleusinc.com/enlargeexhibit.php?ID=797

Picture retrieved from http://thestar.com.my/archives/2006/12/9/sports/Sazali.jpg

Manubrium Sternum Retrieved from http://en.wikipedia.org/wiki/Image:Human_arm_bones_diagram.svg

Structure of the Shoulder Sternoclavicular joint Acromioclavicular joint Coracoclavicular joint Glenohumeral joint Scapulothoracic joint

Structure of the Shoulder Interclavicular ligament Clavicle Sternoclavicular ligament Costoclavicular ligament Sternum Articular disk Costal cartilage (1st rib) Sternoclavicular joint: modified ball and socket joint between the proximal clavicle and the manubrium of the sternum

Structure of the Shoulder Coracoclavicular ligament Anterior view Posterior view Clavicle Verterbal border Acromioclavicular joint Acromion process Coracoacromial ligament Coracoid process Glenoid fossa Axillary border Inferior angle Scapular spine Vertebral border Acromioclavicular joint: irregular joint between the acromion process of the scapula and the distal clavicle

Structure of the Shoulder Coracoclavicular ligament Anterior view Posterior view Clavicle Verterbal border Acromioclavicular joint Acromion process Coracoacromial ligament Coracoid process Glenoid fossa Axillary border Inferior angle Scapular spine Vertebral border Coracoclavicular joint: syndesmosis with the coracoid process of the scapula bound to the inferior clavicle by the coracoclavicular ligament

Structure of the Shoulder Acromion process Coracohumeral ligament Long head of biceps Humerus Coracoid process Articular capsule Scapula Glenohumeral joint: ball and socket joint in which the head of the humerus articulates with the glenoid fossa of the scapula

Structure of the Shoulder What is the scapulothoracic joint? articulation between the anterior scapula and the thoracic wall

Bursae A small fluid-filled sac located between movable parts of the body especially at joints Reduce friction between layers of collagenous tissue

Movements of the Shoulder Complex scapulohumeral rhythm: a regular pattern of scapular rotation that accompanies and facilitates humeral abduction

Movements of the Shoulder Complex First 30o humeral elevation, contribution of scapula only 1/5 of glenohumeral joint Beyond 30o, scapula rotates 1o for every 2o of humerus movement First 90o of arm elevation, clavicle elevated 35o to 45o of motion at sternoclavicular joint.

Movements of the Shoulder Complex What muscles contribute to flexion at the glenohumeral joint? anterior deltoid clavicular pectoralis major assisted by: coracobrachialis short head of biceps brachii

Retrieved from http://upload.wikimedia.org/wikipedia/commons/d/de/Gray410.png

Movements of the Shoulder Complex What muscles contribute to extension at the glenohumeral joint? sternal pectoralis major latissimus dorsi teres major assisted by: long head of triceps brachii

Retrieved from http://upload.wikimedia.org/wikipedia/commons/d/d6/Deltoideus_posterior.PNG

Movements of the Shoulder Complex What muscles contribute to abduction at the glenohumeral joint? middle deltoid supraspinatus

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Movements of the Shoulder Complex What muscles contribute to adduction at the glenohumeral joint? latissimus dorsi teres major sternal pectoralis major assisted by: short head of biceps brachii long head of triceps brachii

Movements of the Shoulder Complex What muscles contribute to medial rotation of the humerus? subscapularis teres major assisted by: pectoralis major anterior deltoid latissimus dorsi short head of biceps brachii

Retrieved from http://upload.wikimedia.org/wikipedia/commons/f/f2/Gray411.png

Movements of the Shoulder Complex What muscles contribute to lateral rotation of the humerus? infraspinatus teres minor assisted by: posterior deltoid

Movements of the Shoulder Complex What muscles contribute to horizontal adduction of the humerus? pectoralis major anterior deltoid coracobrachialis assisted by: short head of biceps brachii

Movements of the Shoulder Complex What muscles contribute to horizontal abduction of the humerus? infraspinatus middle and posterior deltoid teres minor assisted by: teres major latissimus dorsi

Torque at shoulder Torque created by weight of arm is the product of arm weight and perpendicular distance between arm’s COG and the shoulder

Torque at shoulder

Sample Problem 1 If the weight of the arm is 33 N, moment arm for the total arm segment is 30 cm, moment arm for deltoid muscle (Fm) is 3 cm. How much force must be supplied by deltoid to maintain the arm in this position? What is the magnitude of the joint reaction force (R)? wt

Common Injuries of Shoulder Dislocation Rotator Cuff Damage Rotator cuff - anatomical term given to the group of muscles and their tendons that act to stabilize the shoulder Example – supraspinatus, infraspinatus, teres minor, subscapularis muscles Rotational Damage

Humeroulnar Joint Retrieved from http://upload.wikimedia.org/wikipedia/commons/9/97/Gray329.png

Structure of the Elbow What is the humeroulnar joint? hinge joint in which the humeral trochlea articulates with the trochlear fossa of the ulna considered to be the elbow joint

Structure of the Elbow What is the humeroradial joint? gliding joint in which the capitellum of the humerus articulates with the proximal end of the radius

Structure of the Elbow What are the radioulnar joints? the proximal and distal radioulnar joints are pivot joints the middle radioulnar joint is a syndesmosis

Movements at the Elbow What muscles contribute to flexion at the elbow? brachialis biceps brachii brachioradialis

Movements at the Elbow What muscles contribute to extension at the elbow? triceps brachii assisted by: anconeus Retrieved from http://upload.wikimedia.org/wikipedia/commons/7/79/Musculusanconeus2.png

biceps be fore force?

Common Injuries of Elbow Sprains and dislocation Epicondylitis Inflammation and sometimes microrupting of collagenous tissue at distal humerus

Wrist Retrieved from http://upload.wikimedia.org/wikipedia/commons/6/66/Gray334.png

Structure of the Wrist What are the radiocarpal joints? condyloid articulations between the radius and the three carpal bones these joints comprise the wrist

Structure of the Wrist What is the function of the retinacula at the wrist? these fibrous bands of fascia form protective passageways through which tendons, nerves, and blood vessels pass

Movements at the Wrist What muscles contribute to flexion at the wrist? flexor carpi radialis flexor carpi ulnaris palmaris longus assisted by: flexor digitorum superficialis flexor digitorum profundus

Retrieved from http://upload.wikimedia.org/wikipedia/commons/5/5f/Gray418.png Retrieved from http://en.wikipedia.org/wiki/Image:Flexor-carpi-radialis.png

Movements at the Wrist What muscles contribute to extension at the wrist? extensor carpi radialis longus extensor carpi radialis brevis extensor carpi ulnaris assisted by: other wrist extensor muscles

F I N G E R Retrieved from http://upload.wikimedia.org/wikipedia/commons/f/f7/X-ray_boy_hand.jpg

Structure of the Hand Joints What are the carpometacarpal joints? the carpometacarpal joint of the thumb is a saddle joint the other carpometacarpal joints are gliding joints

Structure of the Hand Joints What are the intermetacarpal joints? irregular joints between the metacarpals that share joint capsules with the carpometacarpal joints

Structure of the Hand Joints What are the metacarpophalangeal joints? condyloid joints between the rounded distal heads of the metacarpals and the concave proximal ends of the phalanges these joints form the knuckles of the hand

Structure of the Hand Joints What are the interphalangeal joints? the proximal and distal interphalangeal joints of the fingers and the single interphalangeal joint of the thumb are all hinge joints

Movements of the Hand flexion What motions are permitted at metacarpophalangeal joints 2-5? flexion extension abduction adduction circumduction

Movements of the Hand What muscles are responsible for motions of the hand? there are nine extrinsic muscles with attachments both proximal and distal to the wrist there are ten intrinsic muscles with both attachments distal to the wrist

Common Injuries of Wrist & Hand Fracture - boxers Injury - golfers Carpal tunnel syndrome Passageway between carpal bone and flexor retinaculum Symptom : pain, numbness along median nerve, clumsiness of finger function, atrophy of muscle

Summary Shoulder Structure Movement and muscle involve Common injuries Elbow Wrist Hand Force initiated and torque - calculation