Chapter 6 The Elbow and Radioulnar Joints Copyright © 2018 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education

The Elbow and Radioulnar Joints Most upper extremity movements involve the elbow and radioulnar joints Usually grouped together owing to their close anatomical relationship Elbow joint movements may be clearly distinguished from those of the radioulnar joints Radioulnar joint movements may be distinguished from those of the wrist

Jump to long description Bones, 1 Ulna is much larger proximally than in radius Radius is much larger distally than the ulna Scapula and humerus serve as proximal attachments for muscles that flex and extend the elbow Jump to long description

Bones, 2 Ulna and radius serve as distal attachments for the same muscles Scapula, humerus, and ulna serve as proximal attachments for muscles that pronate and supinate the radioulnar joints Distal attachments of radioulnar joint muscles are located on the radius

Jump to long description Bones, 3 Bony landmarks Medial condyloid ridge Olecranon process Coranoid process Radial tuberosity Jump to long description

Bones, 4 Medial epicondyle Lateral epicondyle Key bony landmarks for wrist and hand muscles Medial epicondyle Lateral epicondyle Lateral supracondylar ridge Jump to long description Jump to long description

Jump to long description Joints, 1 Elbow - Ginglymus or hinge-type joint Allows only flexion and extension Interrelated joints Humeroulnar joint Radiohumeral joint Jump to long description

Joints, 2 Elbow motions Primarily involve movement between articular surfaces of the humerus and ulna Specifically the humeral trochlear fitting into the ulna trochlear notch Radial head has a relatively small amount of contact with the capitulum of the humerus As the elbow reaches full extension, the olecranon process is received by the olecranon fossa

Jump to long description Joints, 3 Increased joint stability when fully extended With the elbow in full flexion, the coranoid process fits into the coranoid fossa As the elbow flexes 20 degrees or more, its bony stability is unlocked, allowing for more side-to-side laxity Jump to long description

Jump to long description Joints, 4 Stability in flexion is more dependent on the lateral or radial collateral ligament and the medial or ulnar collateral ligament Ulnar collateral ligament is critical in providing medial support to prevent the elbow from abducting when stressed during physical activity Jump to long description

Joints, 5 Many contact sports and throwing activities place stress on medial aspects of the joint, resulting in injury Ulnar collateral ligament (UCL) Particularly crucial to high-velocity sporting activities, such as baseball pitching, that require optimal medial elbow stability Compromise of this structure often requires surgery

Joints, 6 Tommy John procedure UCL surgical reconstruction using a tendon graft such as the palmaris longus tendon Radial collateral ligament provides lateral stability and is rarely injured Annular ligament provides a sling effect around the radial head for stability

Joints, 7 Elbow moves from 0 degrees of extension to 145 to 150 degrees of flexion Flexion: zero to 150 degrees Extension: 150 degrees to zero Hyperextension: measured in degrees beyond the zero starting point This motion is not present in all persons When it is present, it may vary from 5 to 15 degrees

Joints, 8 Carrying angle In the anatomical position, it is common for the forearm to deviate laterally from the arm between 5 to 15 degrees Slightly greater in a dominant limb than in a nondominant limb Females commonly have a slightly greater carrying angle than men

Joints, 9 Trochoid or pivot-type joint Radioulnar joint Trochoid or pivot-type joint Radial head rotates around at the proximal ulna Distal radius rotates around the distal ulna Annular ligament maintains the radial head in its joint Jump to long description Jump to long description

Jump to long description Joints, 10 Jump to long description

Joints, 11 Supinates 80 to 90 degrees from the neutral position Radioulnar joint Supinates 80 to 90 degrees from the neutral position Pronates 70 to 90 degrees from the neutral position Pronation: zero to 80 or 90 degrees Supination: zero to 80 or 90 degrees Total forearm motion: 160 to 180 degrees Persons may vary in the range of supination and pronation Some may reach the 90-degree arc, and others may have only 70 degrees plus

Joints, 12 Called syndesmosis because the joint between shafts of the radius and ulna are held tightly together between the proximal and distal articulations by an interosseus membrane Substantial rotary motion between the bones

Joints, 13 Synergy among the glenohumeral, elbow, and radioulnar joint muscles As the radioulnar joint goes through its ROM, the glenohumeral and elbow muscles contract to stabilize or assist in the effectiveness of movement at the radioulnar joints Example - When tightening a screw with a screwdriver that involves radioulnar supination, we tend to externally rotate and flex the glenohumeral and elbow joints, respectively

Joints, 14 Conversely, when loosening a tight screw with pronation, we tend to internally rotate and extend the elbow and glenohumeral joints, respectively We depend on both the agonists and antagonists in the surrounding joints to provide an appropriate amount of stabilization and assistance with the required task

Movements, 1 Flexion Movement of the forearm to the shoulder by bending the elbow to decrease its angle Extension Movement of the forearm away from the shoulder by straightening the elbow to increase its angle

Movements, 2 Pronation Internal rotary movement of the radius on the ulna that results in the hand moving from a palm-up to a palm-down position

Movements, 3 Supination External rotary movement of the radius on the ulna that results in the hand moving from a palm-down to a palm-up position

Jump to long description Muscles, 1 Elbow flexors Biceps brachii Brachialis Brachioradialis pronator teres Elbow extensors Triceps brachii Anconeus Jump to long description

Jump to long description Muscles, 2 Deltoid, pectoralis major, and pectoralis minor muscles removed to reveal deeper structures Jump to long description

Jump to long description Muscles, 3 Radioulnar pronators Pronator teres Pronator quadratus Brachioradialis Radioulnar supinators Biceps brachii Supinator muscle Jump to long description

Muscles, 4 Tennis elbow - Common problem usually involving the extensor digitorum muscle near its origin on the lateral epicondyle Known as the lateral epicondylitis or depending upon specific pathology may be termed lateral epicondylagia or lateral epicondylosis Associated with gripping and lifting activities

Muscles, 5 Somewhat less common and is known as golfer's elbow Medial epicondylitis Somewhat less common and is known as golfer's elbow Associated with the medial wrist flexor and the pronator group near their origin on the medial epicondyle Both conditions involve muscles that cross the elbow but act primarily on the wrist and hand

Jump to long description Muscles, 6 Anterior Primarily flexion and pronation Biceps brachii Brachialis Brachioradialis Pronator teres Pronator quadratus Jump to long description

Jump to long description Muscles, 7 Posterior Primarily extension and supination Triceps brachii Anconeus Supinator Jump to long description

Nerves, 1 All elbow and radioulnar joints muscles are innervated from the median, musculotaneous, and radial nerves of the brachial plexus

Jump to long description Nerves, 2 Radial nerve - Originates from C5, C6, C7, and C8 Triceps brachii Brachioradialis Supinator (posterior interosseous nerve) Anconeus Provides sensation to the posterolateral arm, forearm, and hand Jump to long description

Jump to long description Nerves, 3 Median nerve - Originates from C6 and C7 Pronator teres Pronator quadratus (anterior interosseus nerve) Provides sensation to the palmar aspect of the hand and first three phalanges, the palmar aspect of radial side of the fourth finger, and the dorsal aspect of index and the long fingers Jump to long description

Nerves, 4 Biceps brachii Brachialis Musculotaneous nerve - Branches from C5 and C6 Biceps brachii Brachialis

Jump to long description Biceps Brachii Muscle Flexion of elbow Supination of forearm Weak flexion of shoulder joint Weak abduction of shoulder joint when externally rotated Jump to long description

Jump to long description Brachialis Muscle True flexion of elbow Jump to long description

Brachioradialis Muscle Flexion of elbow Pronation from supinated position to neutral Supination from pronated position to neutral Jump to long description

Triceps Brachii Muscle All heads Extension of elbow Long head Extension of shoulder joint Adduction of shoulder joint Horizontal abduction Jump to long description

Jump to long description Anconeus Muscle Extension of elbow Jump to long description

Jump to long description Pronator Teres Muscle Pronation of forearm Weak flexion of elbow Jump to long description

Pronator Quadratus Muscle Pronation of forearm Jump to long description

Jump to long description Supinator Muscle Supination of forearm Jump to long description

Web Sites, 1 Pitching Biomechanics Evaluation American Sports Medicine Institute www.asmi.org/bioEval.php?page=bio_eval Pitching Biomechanics Evaluation University of Washington School of Medicine www.orthop.washington.edu/PatientCare/OurServices/ShoulderElbow.aspx Information on various upper extremity conditions

Web Sites, 2 A Patient’s Guide to Elbow Anatomy eOrthopod http://eorthopod.com/elbow-anatomy/ A Patient’s Guide to Elbow Anatomy Huei Ming Chai www.pt.ntu.edu.tw/hmchai/Kines04/KINupper/Elbow.htm Functions, stability and joint structure of elbow complex; kinematics, muscle action and common injuries of the elbow

Web Sites, 3 Evaluation of overuse elbow injuries. American Family Physician www.aafp.org/afp/20000201/691.html Evaluation of overuse elbow injuries. Wheeless’ Textbook of Orthopaedics www.wheelessonline.com An extensive index of links to the fractures, joints, muscles, nerves, trauma, medications, medical topics, lab tests, and links to orthopaedic journals and other orthopaedic and medical news.

Appendices

Bones, 1 - Appendix It highlights the lateral supracondylar ridge, lateral epicondyle, capitulum, head of radius, radial tuberosity, radius, ulna, ulnar tuberosity, coronoid process, trochlea, medial epicondyle, medial supracondylar ridge, and coronoid fossa. Jump to the image

Bones, 3 - Appendix It includes the humerus, coronoid fossa, trochlea, radial tuberosity, radius, ulna, ulnar tuberosity, coronoid process, trochlear notch, olecranon process, medial epicondyle, and medial supracondylar ridge. Jump to the image

Bones, 4 - Appendix, 1 It highlights the humerus, coronoid fossa, trochlea, radial tuberosity, radius, ulna, ulnar tuberosity, coronoid process, trochlear notch, olecranon process, medial epicondyle, and medial supracondylar ridge. Jump to the image

Bones, 4 - Appendix, 2 It highlights the lateral supracondylar ridge, olecranon fossa, lateral epicondyle, olecranon process, radial notch, ulna, radius, radial tuberosity, radial head, capitulum, and humerus. Jump to the image

Joints, 1 - Appendix It highlights the joint capsule, lateral epicondyle of the humerus, annular ligament, insertion of the tendon of the biceps brachii muscle (cut), radius, ulna, ulnar collateral ligament, medial epicondyle of humerus, and humerus. Jump to the image

Joints, 3 - Appendix It highlights the tendon of biceps brachii muscle (cut), joint capsule, synovial membrane, radius, ulna, coronoid process, olecranon, olecranon bursa, synovial membrane, trochlea, and humerus. Jump to the image

Joints, 4 - Appendix It highlights the tendon of biceps brachii muscle (cut), coronoid process of ulna, ulnar collateral ligament, medial epicondyle of humerus, joint capsule, and annular ligament. Jump to the image

Joints, 9 - Appendix, 1 It highlights the radial notch of ulna, head of radius, coronoid process, trochlear or semilunar notch, and olecranon process. Jump to the image

Joints, 9 - Appendix, 2 It highlights the posterior, anterior, radial notch, coronoid process, trochlear notch, and olecranon process. Jump to the image

Joints, 10 - Appendix The parts shown by both the anterior and the posterior view are the radius, ulna, interosseous margins, interosseous membrane, ulnar notch of radius, head of ulna, and styloid process. The anterior view also shows the olecranon, radial notch of ulna, head of radius, neck of radius, tuberosity of radius, styloid process, articular facets, tuberosity of ulna, coronoid process, and trochlear notch. The posterior view also shows the olecranon, head of radius, neck of radius, and styloid process. Jump to the image

Muscles, 1 - Appendix It highlights the origins on both the right and the left sides; scapula; humerus; bellies; insertion on both the right and the left sides; radius; ulna; extensors, which include the triceps brachii, long head, and lateral head; and flexors, which include the biceps brachii and the brachialis. Jump to the image

Muscles, 2 - Appendix The lateral view highlights the spine of scapula; acromion process; clavicle; deltoid; pectoralis major; biceps brachii, which includes the long head; brachialis; brachioradialis; anconeus; and the triceps brachii which includes the long head and the lateral head. The anterior view highlights the serratus anterior cut; coracobrachialis; teres major; tendon of latissimus dorsi; triceps brachii, which includes the long head and medial head; medial epicondyle of humerus; brachialis; aponeurosis of biceps brachii; ulna; radius; pronator teres; biceps brachii tendon; and biceps brachii, which includes the short head and long head. Jump to the image

Muscles, 3 - Appendix The arm in the positions of supination and pronation includes the lateral epicondyle, the medial epicondyle, the supinator, the pronator teres, the ulna, the radius, and the pronator quadratus. The cross section of muscle actions includes the biceps brachii, the radius, the bursa, the ulna, and the supinator. Jump to the image

Muscles, 6 - Appendix It highlights the trapezius m., the clavicle, the deltoid m., the triceps brachii m., the brachioradialis m., the pectoralis major m., the biceps brachii–short head, the biceps brachii–long head, the brachialis m., the pronator teres m., the bicipital aponeurosis, the flexor carpi radialis m., the palmaris longus m., the flexor carpi ulnaris m., the flexor digitorum superficialis m., the flexor retinaculum, and the palmar aponeurosis. Jump to the image

Muscles, 7 - Appendix It highlights the trapezius m., the ulnar nerve, the anconeus, the flexor carpi ulnaris m., the extensor carpi ulnaris m., the extensor retinaculum, the acromion process of scapula, the deltoid m., the triceps brachii m., the brachioradialis m., the extensor carpi radialis longus m., the extensor carpi radialis brevis m., the extensor digitorum m., and the extensor digiti minimi m. Jump to the image

Nerves, 2 - Appendix It highlights the medial cord of brachial plexus, the posterior cord of brachial plexus, the lateral cord of brachial plexus, the radial nerve, the lateral head of triceps brachii m., the brachioradialis m., the extensor carpi radialis longus m., the extensor carpi radialis brevis m., the abductor pollicis longus m., the extensor pollicis longus and brevis m m., the extensor indicis m., the extensor retinaculum, the extensor digitorum m., the extensor digiti minimi m., the extensor carpi ulnaris m., the supinator m., the anconeus m., the medial head of triceps brachii m., and the long head of triceps brachii m. The parts of the arm that are covered by these nerves are also highlighted. Jump to the image

Nerves, 3 - Appendix It highlights the posterior cord of brachial plexus, the lateral cord of brachial plexus, the medial cord of brachial plexus, the median nerve, the pronator teres m., the flexor carpi radialis m., the palmaris longus m., the superficial digital flexor m., the deep digital flexor m., the flexor retinaculum, the lateral lumbricales m m., the thenar m m., the pronator quadratus m., and the flexor pollicis longus m. The parts of the arm that are covered by these nerves are also highlighted. Jump to the image

Biceps Brachii Muscle - Appendix The first image highlights the long and short heads of biceps brachii and the I, bicipital aponeurosis, and the second image highlights the O, coracoid process; the O, supraglenoid tubercle; and the I, radial tuberosity. O represents origin, and I represents insertion. Jump to the image

Brachialis Muscle - Appendix The first image highlights the brachialis muscle, and the second image illustrates I, coronoid process of ulna and O, distal half of anterior portion of humerus. O represents origin, and I represents insertion. Jump to the image

Brachioradialis Muscle - Appendix The first image highlights brachioradialis m., and the second image highlights the O, distal two-thirds of the lateral condyloid or supracondylar ridge of the humerus and the I, lateral surface distal end of radius at styloid process. O represents origin, and I represents insertion. Jump to the image

Triceps Brachii Muscle - Appendix The first image highlights the lateral head, the long head, and the medial head of the triceps brachii muscle in extension. The second image highlights the I, olecranon process of the ulna, the O, infraglenoid tubercle of the scapula, the O, distal two-thirds of posterior surface of humerus, and the O, upper half of posterior surface of the humerus. O represents origin, and I represents insertion. Jump to the image

Anconeus Muscle - Appendix The first image highlights the anconeus muscle in extension. The second image highlights I, posterior surface of the upper ulna and olecranon and the O, posterior surface of the lateral condyle of humerus. O represents origin, and I represents insertion. Jump to the image

Pronator Teres Muscle - Appendix The first image highlights pronator teres m. The second image highlights O, distal part of medial condyloid ridge of humerus, medial side of proximal ulna and I, middle third of the lateral surface of the radius. O represents origin, and I represents insertion. Jump to the image

Pronator Quadratus Muscle - Appendix The first image highlights pronator quadratus m. The second image highlights O, distal fourth of anterior side of ulna, and I, distal fourth of anterior side of radius. O represents origin, and I represents insertion. Jump to the image

Supinator Muscle - Appendix The first image highlights posterior view of supinator m. The second image highlights the posterior and anterior views of supinator muscle. These views include O, neighboring posterior part of ulna and I, lateral surface of proximal radius just below head. The posterior view also shows the O, lateral epicondyle of the humerus. O represents origin, and I represents insertion. Jump to the image