bio mechanics of the elbow
DESCRIPTION
Review anatomy of elbow and its function. Analyze overall mechanical effects on elbow during movement.TRANSCRIPT
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The Elbow Complex
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Osteology
• Consist of– Humerus– Ulna– Radius
Anterior aspect
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Osteology
Posterior aspect
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Bony Anatomy: Humerus
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Osteology
Radius Ulna
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Joints of Elbow
• Humeroulnar joint
• Humeroradial joint
• Radioulnar joint
– Proximal radioulnar joint
– Distal radioulnar joint
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• Humeroradial joint
– gliding joint in which the
capitellum of the humerus
articulates with the proximal
end of the radius
Joints of Elbow
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• Humeroulnar joint
– hinge joint in which the humeral
trochlea articulates with the
trochlear fossa of the ulna
Joints of Elbow
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Joints of Elbow
• Radioulnar joint– the proximal and distal radioulnar
joints are pivot joints
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Ligaments of the Elbow
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Lateral Ligamentous Structures
• Lateral/radial collateral ligament – origin
is near axis of elbow flexion/extension, so fibers uniformly tight throughout ROM
• Annular ligament – inserts on
anterior/posterior margins of lesser (radial) semilunar notch, maintains radial head in contact with ulna (forms 4/5 of fibro-osseous ring)
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Ligaments of the Elbow
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Medial Ligamentous Structures
• Medial/Ulnar Collateral Ligament– Anterior bundle –
most discrete segment
– Posterior bundle – thickening of posterior capsule
– Transverse bundle – spans medial border of semilunar notch, little/no contribution to elbow stability
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Vascular
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Vascular
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Nervous Innervation
Median nerve
Ulnar nerve
Radial nerve
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Median Nerve
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Ulnar Nerve
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Range of Motion
• Flexion/extension –
ginglymus joint (ulnohumeral articulation)
• Flexion typically 0-150 degrees, stops due to soft tissue approximation
• Extension typically 0-10 degrees (hyperextension, especially in females), stops due to bony opposition
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Range of Motion
• Forearm pronation and
supination – trochoid
joint (radiohumeral and
proximal radioulnar
articulations)
• Pronation/supination
typical 0-85/90 degrees
each from neutral point
(thumb up), stops due to
tissue tensions/stretch
from opposing tissue
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Movements of the Elbow
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• Flexion
– Brachialis
– Biceps Brachii
– Brachioradialis
Movements of the Elbow
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Brachialis Biceps brachii Brachioradialis
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• Extension
– Triceps Brachii
– Assisted By:
• Anconeus
Movements of the Elbow
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Triceps brachii
Anconeus
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• Pronation
– Pronator teres
– Pronator quadratus
Movements of the Elbow
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Pronator teres Pronator quadratus
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Movements of the Elbow
• Pronation– Flexor group
• Pronator teres• Flexor carpi
radialis• Flexor digitorum
superficialis• Flexor digitorum
profundus• Palmaris longus• Flexor carpi
ulnaris
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Flexor Carpi Radialis
Flexor Carpi Ulnaris
Flexor Digitorum Superficialis
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Flexor Digitorum Profundus
Palmaris Longus
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• Supination
– Supinator
– Biceps brachii
Movements of the Elbow
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SupinatorBiceps brachii
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Movements of the Elbow
• Supination – Extensor group
• Supinator• Extensor carpi
radialis longus• Extensor carpi
radialis brevis• Extensor carpi
ulnaris• Extensor
digitorum
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Extensor Carpi Radialis Longus
Extensor Carpi Radialis Brevis
Extensor Carpi Ulnaris
Extensor Digitorum
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Supination and Pronation
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Elbow Kinematics• One of the most congruous and
stable joints• In extension, anterior capsule
provides most restraint, while MCL becomes primary stabilizer at 90 degrees flexion
• Annular ligament encircles the head of the radius, stabilizing it in the radial notch
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Elbow Kinematics
• Varus stress – In extension resisted by bone structure,
LCL and lateral joint capsule – In flexion, resisted primarily by bone
structure
• Valgus stress – In flexion, resisted primarily by MCL – In extension equally resisted by bone
structure, MCL and medial joint capsule
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Load on the Elbow
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Load on the Elbow
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Load on the Elbow
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Biomechanics of Elbow Flexors
• Dominant side produces higher flexion torque, work, and power
• Flexion torques are 70% higher than extension
• Flexion torques are 20-25% higher in supinated versus pronated positions due to increased flexor moment arm of biceps and brachioradialis
• Max torque at 90°
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Biomechanics of Elbow Extensors
• Generate large and dynamic extensor torques through high-velocity concentric and eccentric activities (throw, push)
• Shoulder flexion with pushing activity, counteracts the tendency of elbow extensors to extend the shoulder