The Elbow and Radioulnar Joints

Bones Humerus Ulnar Radius trochlea of the humerus capitulum: spherical knob on lateral side medial and lateral epicondyle Ulnar Trochlear notch of ulna Olecranon Process on posterior aspect radial notch coronoid process ulnar tuberosity Radius Head radial tuberosity

The Elbow Joint Classified as a ginglymus (hinge) joint The ELBOW consists of 2 joints: humeroulnar olecranon process of the ulnar distal aspect of humerus radiohumeral radial head has small amount of articulation with humerus (capitulum)

Proximal Radioulnar Joint articulation between radius and ulnar not part of “hinge” joint trochoid (pivot) joint allows for forearm pronation/supination

Movements Elbow Forearm movements about the Proximal Radioulnar joint Flexion Extension Forearm movements about the Proximal Radioulnar joint Supination: Lateral rotation Pronation: Medial Rotation

Muscles Posterior Triceps brachii Anconeus Supinator Anterior Biceps brachii Brachialis Brachioradialis Pronator teres Pronator quadratus Posterior Triceps brachii Anconeus Supinator

Muscles Elbow Flexors biceps brachii brachialis brachioradialis pronator teres

Muscles Elbow Extensors Forearm Pronators triceps brachii anconeus pronator teres pronator quadratus brachioradialis*

Muscles Forarm Supinators supinator biceps brachii brachioradialis*

Anconeus (p56) Origin Insertion Action posterior surface of lateral epicondyle of humerus Insertion ulna, posterior surface of olecranon process Action elbow extension

Biceps Brachii (p 57) Origin: long head: supraglenoid tubercle short head: coracoid process Insertion radial tuberosity Action: elbow flexion, supination, (weak shoulder flexor)

Brachialis (p58) Origin Insertion Action Lower portion of anterior surface of humerus Insertion coronoid process of ulna ulna tuberosity Action elbow flexion (‘true’ flexor)

Brachioradialis (p59) Origin Insertion Action upper 2/3 of lateral supracondylar ridge of humerus Insertion styloid process of radius Action elbow flexion supination (from pronated position to neutral) *pronation (from supinated position to neutral)

Pronator Quadratus (p60) Origin ulna, anterior-distal fourth aspect Insertion radius, anterior-distal fourth Action pronation

Pronator teres (p61) Origin Insertion Action humerus, medial epicondyle ulna, cornoid process Insertion radius, middle third, lateral surface Action pronation elbow flexor

Supinator (p62) Origin Insertion Action Humerus, lateral epicondyle Ulna, supinator crest of ulna Insertion radius, lateral surface, upper 1/3 Action supination

Triceps Brachii (p63) Origin Insertion long head: scapula, infraglenoid tubercle lateral head: humerus, 1/3 lagteral-posterior surface medial head: humerus, lower 3/4 of posterior surface Insertion olecranon process of ulna Action All heads: elbow extension Long head: arm extension, arm adduction

Summary Elbow and Proximal Radioulnar Joints Bones Actions Humerus, ulna, radius Actions Elbow (about humeralulnar joint) flexion, extension Forearm (about Proximal Radioulnar joint) pronation, supination