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