Functional Anatomy

of the Elbow

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

Orthopedic Institute

• 3 major peripheral

nerves

• 3 major complex joint

articulations

• obstacles /

complications

Intricate Joint

• Allows objects to be

positioned away from the

body with the elbow in full

extension

• Mean adult population

17.8°

Center of rotation

of shoulder

Center of gravity load

Elbow Carrying Angle

“normal valgus position”

• 3 bones

Humerus

Ulna

Radius

• 3 articulations

Ulnohumeral

Radiocapitellar

Proximal Radioulnar

Humerus

ulna radius

The Elbow Joint

Medial Column

- UCL

- Coronoid Process

- Medial Condyle

Lateral Column

- Radial Head

- Capitellum

- LCL & LUCL

Anterior Column

- Coronoid Process

- Brachialis

- Anterior capsule

Posterior Column

- Olecranon Process

- Triceps

- Posterior Capsule

Elbow Stability

Outline

• Osseous Architecture

• Ligaments

• Musculature

• Nerves

• Vasculature

Outline

• Osseous Architecture

• Ligaments

• Musculature

• Nerves

• Vasculature

A: anterior view B : posterier view

trochlea trochlea

Lateral

column

Medial

column

Humerus: Anterior & Posterior View

* With internal fixation of a distal humerus fracture, all

three arms of the triangle need to be stabilized

Lateral

column

Medial

column

Trochlea

Distal Humeral Triangle

Anterior view Posterior view

45 ° 45 °

Medial Epicondyle Groove for

Ulnar Nerve

Distal Humerus: Medial Side

Anterior view Posterior view

Capitellum

Radial

fossa

Lateral Supracondylar

Ridge

BR ECRL

Lateral epicondyle Lateral

epicondyle

20°

Distal Humerus: Lateral Side

• Radiohumeral ( 60% )

Ulnohummeral ( 40% )

• Greater Force in

pronation vs supination

Applied Force

40% 60%

Humerus ( H )

Radius ( R )

Ulna ( U )

H

R U

Elbow Articular Surface Forces

• Single axis of motion in

flexion & extension

• constrained hinged joint

• ulnohumeral articulation

Humerus

radius

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

Ulnohumeral Joint

Radiocapitellar & Radioulnar Joint

• Pivot joints

• Allow supination and pronation.

• 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.

Radiocapitellar & Radioulnar Joint

Anterior view

Lateral view

Olecranon Process

Sigmoid or Trochlear Notch

** Coronoid process

*

*

Radial Notch

* articulates with

radial head

Supinator Crest

* LUCL

* Supinator muscle

Ulna

Radial

head

Neck of

radius

radius

ulna

radius

Radial Tuberosity

* *Biceps brachii

attachment

**

**

15°

Radius

Outline

• Osseous Architecture

• Ligaments

• Musculature

• Nerves

• Vasculature

Anterior Bundle

radius

ulna

Posterior bundle

humerus

Transverse Bundle

* Anterior bundle: primary

stabilizer 60 - 90 °

* Significant UCL instability

w/ Coronoid fractures

* Posterior bundle:

Weak fan shaped

Ulnar Collateral Ligament

Radial

Collateral

Ligament

Lateral Ulnar Collateral Ligament

* primary restraint to posterolateral instability

ulna

radius

Annular Ligament

Lateral Collateral Ligament Complex

• Strong fibrocartinlaginous

band

• Encircles the radial head

• Permits radius to rotate

around ulna ulna

Radius

Annular

ligament (AL)

Lesser

Trochlear

notch

Coronoid

process Radial

head

Anterior view

(AL)

Annular Ligament

Anterior Posterior

proximal proximal

distal distal

Elbow Joint Capsule

• Observed on

lateral radiographs

• Intraarticular

effusion will cause

displacement

• Potential to block

extension

Synovial

Space

Fat Pad

ulna

humerus

Elbow Fat Pad

Outline

• Osseous Architecture

• Ligaments

• Musculature

• Nerves

• Vasculature

• Flexors

• Extensors

• Pronators

• Supinators

Muscles

Primary

Brachialis Secondary

Brachioradialis

Musculocutaneous nerve Radial nerve

Flexion

• Dual functions supination

and flexion

• Long and short heads

• With forearm fully

pronated, biceps inactive

• With elbow fully

extended & pronated,

biceps inhibited

Biceps Brachii

Musculocutaneous

nerve

Supination

Supinator Muscle

• Secondary FA supinator

• Superficial and deep heads

• Radial Nerve Innervation

• Arcade of Froshe

• Posterior Interosseous

Nerve

• Acts alone when supination

is unresisted

Supinator

Posterior

Interosseus

Nerve

Supination

Lateral Head

Long Head

Medial Head

Triceps

* Radial nerve

Anconeus

Anconeous

* Radial nerve

Extension

• Superficial and deep

heads

• Median nerve

• Inserts into the middle

1/3 of radius

Median nerve

Pronator Teres

Pronation

Brachioradialis

Biceps

tendon

Medial epicondyle

* Pronator Teres ( PT ) * Flexor Carpi Radialis ( FCR ) * Palmaris Longus ( PL )

* Flexor Carpi Ulnaris ( FCU )

Medial Elbow: Flexor-Pronator

Lateral epicondyle

* Anconeus

* Extensor Carpi Ulnaris ( ECU )

* Extensor Digiti Quinti ( EDQ )

* Extensor Digitorum Comminus ( EDC )

Lateral supracondylar

ridge

* Brachioradialis ( BR )

* Extensor Carpi Radialis

Longus ( ECRL )

* Extensor Carpi Radialis Brevis ( ECRB )

Lateral Elbow: Extensor Tendons

Outline

• Osseous Architecture

• Ligaments

• Musculature

• Nerves

• Vasculature

• Radial

• Median

• Ulnar

Nerves

Radial Nerve

Triceps (LH, MH, LatH)

Anconeus

Brachioradialis

Extensor Carpi Radialis Longus (ECRL)

Posterior Interosseous Nerve (PIN)

Extensor Carpi Radialis Brevis (ECRB)

Supinator (Arcade of Froshe)

Extrinsic wrist extensors

Radial nerve

LH Triceps

MH Triceps

Lateral Head

Triceps

Anconeus

Brachioradialis

ECRL

ECRB

Supinator

XX Extrinsic

wrist

muscles XX Radial Tunnel Radiocapitellar joint line Lateral Epicondyle

Radial Nerve

Pronator Teres

Flexor Carpi Radialis

Palmaris Longus

Flexor Digitorum

Superficialis

Flexor Pollicis

Longus

Flexor Digitorum

Profundus (radial part)

Flexor Digitorum

Profundus (ulnar part)

Pronator

Quadratus

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

Median Nerve

Innervation

• Flexor Carpi Ulnaris

• Flexor Digitorum

Profundus (ulnar II)

• Intrinsics

Lateral view

Ulnar nerve

Cubital tunnel

retinaculum

Medial Epicondyle humerus

Cubital tunnel

Flexor Carpi Ulnaris

(FCU) Humeral Head

FCU

Ulnar Head

Ulnar Nerve

• Medial

antebrachial

cutaneous nerve

• Lateral

antebrachial

cutaneous nerve

Musculocutaneus

Ulnar

Radial

Median

Anterior view Posterior view

Cutaneous Nerves

Outline

• Osseous Architecture

• Ligaments

• Musculature

• Nerves

• Vasculature

Brachial artery

Superior ulnar collateral artery

Inferior ulnar collateral artery

Ulnar recurrent arteries

Radial Artery

Middle collateral

artery

Radial collateral

artery

Radial recurrent

artery

Anterior

View

Ulnar Artery

Vascular

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