Functional Anatomy of the Elbow Orthopedic Institute Daryl C. Osbahr, M.D. Chief of Sports Medicine, Orlando Health Chief Medical Officer, Orlando City Soccer Club Orthopedic Consultant, Washington Nationals Orthopedic Consultant, WWE NXT
Intricate Joint 3 major peripheral nerves 3 major complex joint articulations obstacles / complications
Elbow Carrying Angle normal valgus position Center of rotation of shoulder Allows objects to be positioned away from the body with the elbow in full extension Mean adult population 17.8 Center of gravity load
The Elbow Joint 3 bones Humerus Ulna Radius Humerus 3 articulations Ulnohumeral Radiocapitellar Proximal Radioulnar ulna radius
Elbow Stability Anterior Column - Coronoid Process - Brachialis - Anterior capsule Lateral Column - Radial Head - Capitellum - LCL & LUCL Medial Column - UCL - Coronoid Process - Medial Condyle Posterior Column - Olecranon Process - Triceps - Posterior Capsule
Outline Osseous Architecture Ligaments Musculature Nerves Vasculature
Outline Osseous Architecture Ligaments Musculature Nerves Vasculature
Humerus: Anterior & Posterior View Lateral column Medial column trochlea trochlea A: anterior view B : posterier view
Distal Humeral Triangle Lateral column Medial column Trochlea * With internal fixation of a distal humerus fracture, all three arms of the triangle need to be stabilized
Distal Humerus: Medial Side Medial Epicondyle 45 45 Groove for Ulnar Nerve Anterior view Posterior view
Distal Humerus: Lateral Side Lateral Supracondylar Ridge BR ECRL Radial fossa Lateral epicondyle Capitellum Anterior view 20 Posterior view Lateral epicondyle
Elbow Articular Surface Forces Applied Force 40% 60% Humerus ( H ) Radius ( R ) Ulna ( U ) H U R Radiohumeral ( 60% ) Ulnohummeral ( 40% ) Greater Force in pronation vs supination
Ulnohumeral Joint Humerus Single axis of motion in flexion & extension constrained hinged joint radius ulnohumeral articulation ulna
Ulnohumeral Joint Provides inherent stability Increases the prominence of the coronoid process to resist posterior subluxation Ensures clearance of coronoid and provides space for the flexor muscles
Radiocapitellar & Radioulnar Joint Pivot joints Allow supination and pronation.
Radiocapitellar & Radioulnar Joint The ulna does not move. The radius moves around the ulna. The ulna is locked in place by the proximal end at the olecranon process.
Ulna * * Sigmoid or Trochlear Notch Olecranon Process ** Coronoid process Anterior view Lateral view Radial Notch * articulates with radial head Supinator Crest * LUCL * Supinator muscle
Radius 15 Radial head Neck of radius radius ulna Radial Tuberosity * *Biceps brachii attachment ** ** radius
Outline Osseous Architecture Ligaments Musculature Nerves Vasculature
Ulnar Collateral Ligament Anterior Bundle radius ulna humerus * Anterior bundle: primary stabilizer 60-90 * Significant UCL instability w/ Coronoid fractures * Posterior bundle: Weak fan shaped Posterior bundle Transverse Bundle
Lateral Collateral Ligament Complex Annular Ligament Radial Collateral Ligament radius ulna Lateral Ulnar Collateral Ligament * primary restraint to posterolateral instability
Annular Ligament Lesser Trochlear notch Radial head Radius (AL) Annular ligament (AL) Coronoid process ulna Strong fibrocartinlaginous band Encircles the radial head Permits radius to rotate around ulna Anterior view
Elbow Joint Capsule proximal proximal distal Anterior distal Posterior
Elbow Fat Pad Synovial Space Fat Pad humerus Observed on lateral radiographs Intraarticular effusion will cause displacement ulna Potential to block extension
Outline Osseous Architecture Ligaments Musculature Nerves Vasculature
Muscles Flexors Extensors Pronators Supinators
Flexion Primary Brachialis Musculocutaneous nerve Secondary Brachioradialis Radial nerve
Supination Biceps Brachii Dual functions supination and flexion Long and short heads Musculocutaneous nerve With forearm fully pronated, biceps inactive With elbow fully extended & pronated, biceps inhibited
Supination Supinator Muscle Secondary FA supinator Posterior Interosseus Nerve Superficial and deep heads Radial Nerve Innervation Supinator Arcade of Froshe Posterior Interosseous Nerve Acts alone when supination is unresisted
Extension Lateral Head Long Head Medial Head Triceps * Radial nerve Anconeous * Radial nerve Anconeus
Pronation Median nerve Pronator Teres Superficial and deep heads Median nerve Inserts into the middle 1/3 of radius
Medial Elbow: Flexor-Pronator * Pronator Teres ( PT ) * Flexor Carpi Radialis ( FCR ) * Palmaris Longus ( PL ) * Flexor Carpi Ulnaris ( FCU ) Brachioradialis Biceps tendon Medial epicondyle
Lateral Elbow: Extensor Tendons * Anconeus * Extensor Carpi Ulnaris ( ECU ) * Extensor Digiti Quinti ( EDQ ) * Extensor Digitorum Comminus ( EDC ) * Extensor Carpi Radialis Brevis ( ECRB ) * Brachioradialis ( BR ) * Extensor Carpi Radialis Longus ( ECRL ) Lateral supracondylar ridge Lateral epicondyle
Outline Osseous Architecture Ligaments Musculature Nerves Vasculature
Nerves Radial Median Ulnar
Radial Nerve Radial nerve LH Triceps MH Triceps Lateral Head Triceps Radial Nerve Triceps (LH, MH, LatH) Anconeus Brachioradialis Extensor Carpi Radialis Longus (ECRL) Anconeus Extrinsic wrist muscles XX Radiocapitellar joint line Brachioradialis ECRL ECRB Supinator Lateral Epicondyle Posterior Interosseous Nerve (PIN) Extensor Carpi Radialis Brevis (ECRB) Supinator (Arcade of Froshe) Extrinsic wrist extensors XX Radial Tunnel
Median Nerve Pronator Quadratus Pronator Teres Flexor Carpi Radialis Palmaris Longus Flexor Digitorum Superficialis Flexor Digitorum Profundus (radial part) Flexor Pollicis Longus Flexor Digitorum Profundus (ulnar part) Median Nerve * Pronator Teres * Flexor Carpi Radialis * Palmaris Longus * Flexor Digitorum Superficialis Anterior Interosseous Nerve * Flexor Pollicis Longus * Flexor Digitorum Profundus (radial II) * Pronator Quadratus Ligament of Struthers Lacertus Fibrosis
Ulnar Nerve Innervation Flexor Carpi Ulnaris Flexor Digitorum Profundus (ulnar II) Intrinsics Flexor Carpi Ulnaris (FCU) Humeral Head humerus Ulnar nerve Medial Epicondyle Cubital tunnel retinaculum Lateral view FCU Ulnar Head Cubital tunnel
Cutaneous Nerves Musculocutaneus Radial Ulnar Medial antebrachial cutaneous nerve Lateral antebrachial cutaneous nerve Median Anterior view Posterior view
Outline Osseous Architecture Ligaments Musculature Nerves Vasculature
Vascular Middle collateral artery Radial collateral artery Brachial artery Superior ulnar collateral artery Inferior ulnar collateral artery Radial recurrent artery Ulnar recurrent arteries Ulnar Artery Radial Artery Anterior View
2016 ACSM Team Physician Course Orthopedic Institute