Elbow Elbow Anatomy. Flexion extension. Pronation Supination. Anatomy. Anatomy. Romina Astifidis, MS., PT., CHT

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1 Elbow Elbow Anatomy Romina Astifidis, MS., PT., CHT Curtis National Hand Center Baltimore, MD October 6-8, 2017 Link between the arm and forearm to position the hand in space Not just a hinge Elbow = 70% upper extremity motion Flex Ext = 42% Pron Sup = 28% Normal Flexion extension Functional (4% loss) Pronation Supination Normal Functional (3% loss) Distal Humerus Proximal Ulna Radial Head Anatomy Anatomy In full ext, 60% of axial loads are transmitted across the radiocapitellar joint while 40% of loads are transmitted across the ulnohumeral joint With elbow flexion, the loads are equally shared between the ulnohumeral and radiocapitellar articulations.

2 capitellum coronoid fossa trochlea Anterior View lateral epicondyle medial epicondyle DISTAL HUMERUS olecranon fossa Posterior View Bony Anatomy Distal Humerus Shaft inclines anteriorly 30 Articular surfaces and joint axis anterior to shaft Creates room for soft tissue and greater flexion Shaft widens for medial and lateral support pillars Aids in maintenance of strength Bony Anatomy Humerus Central depressions anteriorly and posteriorly Room for coranoid and olecrenon process respectively Maximizes range of motion Boney Anatomy Humerus Articular surfaces Trochlea medially articulates with the proximal ulna Capitulum laterally articulates with the proximal radius. tuberosity RADIUS neck head head Radial Head A secondary stabilizer to both varus and valgus forces if the MCL and LCL are intact If MCL or LCL is deficient, then radial head becomes a primary stabilizer Radial head is offset from the neck 15 degreesimplications with fracture fixation or prosthetic replacement Radial head is cylindrical and concave proximally

3 ULNA shaft coronoid process olecranon process radial notch Clearly the major determinant of elbow stability Ulno humeral integrity is key to stability ~30% of articular surface must be intact Coronoid is key to prevent posterior subluxation Proximal Ulna Coronoid ~50% of coronoid must be present for the elbow to function Deficient coronoid will result in posterior instability Trochlear notch is anterior to shaft and directed anterosuperiorly Axis anterior to shaft Arc of notch less than 180 degrees Bony Anatomy Ulna Coronoid Stability Primarily a function of the bony anatomy Secondarily a function of ligamentous anatomy Anatomy Elbow stability Bony Contributions Olecranon Process 30% of articulation required for stability Coranoid Critical as an anterior buttress for posteriorly directed forces. Approximately 50% required for stability. Radial Head Contributes 30% to valgus stability with intact MCL and 75% with deficient MCL. Bears 60% of axial load in ext

4 Stability Primary stabilizing Factors A complex interaction among the bones and ligaments to resist physiologic stress applied to the elbow A deficiency in one area can be compensated for by other intact structures (ie radial head and MCL in valgus force) Soft tissues that contribute to the stability include the collateral ligaments and the capsule both anteriorly and posteriorly. Dynamic stability is also provided by the actions of the muscles crossing the joint. Medial Collateral Ligament Anterior band of the MCL most important for both valgus and varus stress Tight 0-60 Rehab of the Hand, 6 th ed Tight Secondary Stabilizing Factors Radial head most important and provides 30% of valgus stability Posterior Capsule is primary restraint to distraction in full ext Lateral Capsule secondary stabilizer to varus stress Anconeous also secondary stabilizer to varus stress Interosseous membrane At the wrist most load is carried by radius At the elbow most load is carried by ulna IOM is where load is transferred Pathology Pathology

5 Capsule Encloses elbow and proximal radioulnar joints ( 3 sets of articular surfaces) Anterior and posterior parts of capsule taut only at end ranges Entire anterior capsule related to brachialis muscle Greatest capacity at 80 degrees why important? Ligaments The ligaments are secondary stabilizers when bones are intact. Medial Collateral ligament (MCL) Goes from medial epicondyle to ulna Anterior band most important Resists valgus forces Lateral Collateral Lateral epicondyle to ulna and annular ligament Maintains relationship of forearm to trochlea and capitellum Resists posterior lateral rotatory instability Annular Ligament Secures radial head to ulna Medial Collateral Ligaments Lateral Collateral Ligaments (LCL) Includes anterior bundle, posterior bundle, transverse bundle Anterior bundle is major stabilizer to valgus stress. Delete this: Stabilizes elbow from Pathology Chronic attenuation Fall Medial epicondylectomy with cubital tunnel Extends from lateral epicondyle to annular ligament for common insertion to ulna Lateral laxity allows prox FA to sublux away from humerus when loaded in supination. Challenged with any varus stretch or load and more unstable in supination.why is this important? Posterolateral rotatory instability Cause LUCL injured with Supinated compressive force with valgus stressusually at degrees ext and reduces in flex Stable Full pronation and some flexion Annular Ligament Attaches to anterior and posterior edges of radial notch and surrounds radial head Holds head in notch and allows head to spin Resists distraction of radius

6 Ligaments Contribution of ligaments depends on elbow position In full extension, the ligaments and anterior capsule become more important In flexion, bony anatomy dominates MCL MCL in elbow extension LCL MCL in elbow flexion Superficial groups of forearm muscles attach (origin) to medial (flexors) and lateral (extensors) humeral epicondyles and collateral ligaments These muscles reinforce collateral ligaments and resist distraction forces Muscle restraints Other Elbow Supports Interosseous ligament (membrane) Supinator Pronator Teres muscles

7 Origin: medial epicondyle and coronoid process Insertion: middle of lateral surface of radius Action: Pronates and flexes Innervation:Median nerve (C6,C7) Arterial supply: Ulnar, anterior recurrent ulnar Pronator Teres 2 originsmedian N Bicep Brachii Origin Short head: tip of coracoid process of scapula; Long head: supraglenoid tubercle of scapula Insertion: Tuberosity of radius and fascia of forearm via bicipital aponeurosis(lacertus fibrosus) Action: Supinates forearm and, when it is supine, flexes forearm Innervation: Musculocutaneous nerve (C5 and C6 ) (C5, C6) Arterial Supply: Muscular branches of brachial Anconeus Origin: Lateral epicondyle of humerus Insertion: Lateral surface of olecranon and superior part of posterior surface of ulna Action: Assists triceps in extending forearm; stabilizes elbow joint; abducts ulna during pronation Innervation: Radial nerve (C7, C8 and T1) (C7, C8, T1) Arterial Supply: Middle collateral branch of deep brachial ; Recurrent interosseous Brachialis Origin: Distal half of anterior surface of humerus Insertion: Coronoid process and tuberosity of ulna Action: Major flexor of forearm flexes forearm in all positions Innervation: Musculocutaneous nerve (C5 and C6) (C5, C6) Arterial Supply: Muscular branches of brachial, recurrent radial Supinator Brachioradialis Origin: Lateral epicondyle of humerus, radial collateral and annular ligaments, supinator fossa and crest of ulna Insertion: Lateral, posterior and anterior surfaces of proximal 1/3 of radius Action: Supinates forearm (i.e., rotates radius to turn palm anteriorly) Innervation: Deep branch of radial nerve (C5 and C6) (C5, C6) Arterial Supply: Recurrent interosseous Origin: Proximal 2/3 of lateral supracondyle ridge of humerus Insertion: Lateral surface of distal end of radius Action: Flexes forearm Innervation: Radial nerve (C5, C6 and C7) (C5, C6, C7) Arterial Supply: Radial recurrent

8 Triceps Origin: Long head: infraglenoid tubercle of scapula; Lateral head: posterior surface of humerus, superior to radial groove; Medial head: posterior surface of humerus, inferior to radial groove Insertion: Proximal end of olecranon process of ulna and fascia of forearm Action: Chief extensor of forearm; long head steadies head of abducted humerus Innervation: Radial nerve (C6, C7 and C8) (C6, C7, C8) Arterial Supply: Branches of deep brachial NAME THE 15 MUSCLES CROSSING THE ELBOW 5 originate on medial epicondyle 2 originate on lateral supracondylar ridge 1 originates on scapula & posterior humeral shaft 1 originates on scapula & anterior humeral shaft 1 originates on anterior humeral shaft 5 originate on lateral epicondyle Cubital Fossa Cubital Tunnel Begins at the condylar groove between the medial epicondyle and the olecranon. Floor of the cubital tunnel is the elbow capsule and MCL Roof is the fascia of the FCU and the arcuate ligament of Osborne (cubital retinaculum) The medial epicondyle and olecranon form the walls. Capacity is greatest when the elbow is in extension because the arcuate ligament is slack. Changes from round shape to oval shape with flexion results in a 55% volume decrease in the canal. The arcade is a thin aponeurotic band extending from the medial head of the triceps to the medial intramuscular septum. Implicated in cubital tunnel syndrome Arcade of Struthers Supinator Arch: Arcade of Frohse Sometimes called the supinator arch Fibrous arch over the posterior interosseous nerve Common site for compression and paralysis

9 Pronator Tunnel Median nerve passes between the 2 heads of the pronator and is site of compression.