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Review anatomy of elbow and its function. Analyze overall mechanical effects on elbow during movement.
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The Elbow Complex
Osteology
• Consist of– Humerus– Ulna– Radius
Anterior aspect
Osteology
Posterior aspect
Bony Anatomy: Humerus
Osteology
Radius Ulna
Joints of Elbow
• Humeroulnar joint
• Humeroradial joint
• Radioulnar joint
– Proximal radioulnar joint
– Distal radioulnar joint
• Humeroradial joint
– gliding joint in which the
capitellum of the humerus
articulates with the proximal
end of the radius
Joints of Elbow
• Humeroulnar joint
– hinge joint in which the humeral
trochlea articulates with the
trochlear fossa of the ulna
Joints of Elbow
Joints of Elbow
• Radioulnar joint– the proximal and distal radioulnar
joints are pivot joints
Ligaments of the Elbow
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)
Ligaments of the Elbow
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
Vascular
Vascular
Nervous Innervation
Median nerve
Ulnar nerve
Radial nerve
Median Nerve
Ulnar Nerve
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
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
Movements of the Elbow
• Flexion
– Brachialis
– Biceps Brachii
– Brachioradialis
Movements of the Elbow
Brachialis Biceps brachii Brachioradialis
• Extension
– Triceps Brachii
– Assisted By:
• Anconeus
Movements of the Elbow
Triceps brachii
Anconeus
• Pronation
– Pronator teres
– Pronator quadratus
Movements of the Elbow
Pronator teres Pronator quadratus
Movements of the Elbow
• Pronation– Flexor group
• Pronator teres• Flexor carpi
radialis• Flexor digitorum
superficialis• Flexor digitorum
profundus• Palmaris longus• Flexor carpi
ulnaris
Flexor Carpi Radialis
Flexor Carpi Ulnaris
Flexor Digitorum Superficialis
Flexor Digitorum Profundus
Palmaris Longus
• Supination
– Supinator
– Biceps brachii
Movements of the Elbow
SupinatorBiceps brachii
Movements of the Elbow
• Supination – Extensor group
• Supinator• Extensor carpi
radialis longus• Extensor carpi
radialis brevis• Extensor carpi
ulnaris• Extensor
digitorum
Extensor Carpi Radialis Longus
Extensor Carpi Radialis Brevis
Extensor Carpi Ulnaris
Extensor Digitorum
Supination and Pronation
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
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
Load on the Elbow
Load on the Elbow
Load on the Elbow
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°
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