Radius, Ulna, Elbow and Radioulnar Joint

College of Allied Health Science

ANATOMY MUSCULOSKELETAL RADIUS & ULNA,

ELBOW AND RADIOULNAR JOINT

HERMIZAN BIN HALIHANAFIAH

Bsc Biomedicine (Hons) UKM

Ulna

Located on the medial aspect (the little

finger side) of the forearm.

Longer than radius.

At the proximal end is the olecranon,

forms the prominence of the elbow.

The coronoid process is an anterior

projection, together with the olecranon

receive the trochlea of the humerus.

Ulna

Anterior view

Trochlear notch

Olecranon

Radial notch

Coronoid process

Lateral view

Cont….

The trochlear notch is a large curved area between

the olecranon and coronoid process that forms part of

the elbow joint.

Just inferior to the coronoid process is the ulnar

tuberosity.

Distal end of the ulna consist of a head that is

separated from the wrist by a fibrocartilage disc.

A styloid process is on the posterior side of the distal

end.

Ulnar Tuberosity

Radius

Located on the lateral aspect (thumb side) of the

forearm.

Proximal end of the radius has a disc shaped head

that articulates with capitulum of the humerus and the

radial notch of the ulna.

Inferior to the head is the constricted neck.

A roughened area inferior to the neck on the medial

side, called the radial tuberosity, is a point attachment

for the tendons of the biceps brachii muscle.

Cont…

The shaft of the radius is widens distally to form a styloid process on the lateral side.

Ulnar Tuberosity

Radius and Ulna

Ulna and radius articulate with the humerus

at the elbow joint.

This articulation occur in 2 places; head of

radius articulate with capitulum of the

humerus, and trochlear notch of the ulna

articulates with trochlea of the humerus.

Elbow Joint

Cont….

Ulna and radius connect with one another at three

sites.

First, a broad, flat, fibrous connective tissue called

interosseous membrane joint the shaft of the two

bones.

This membrane also provide a site of attachment

for some tendons of deep muscles of the forearm.

Elbow Joint

Proximal Radioulnar Joint

Distal

Radioulnar Joint

Interosseous Membrane

Radiocarpal Joint

Cont…

Ulna and radius also articulates at their proximal

and distal end.

Proximally, the head of radius articulates with the

radial notch of ulna, depression that is lateral and

inferior to the trochlear notch of ulna.

This articulation is the proximal radioulnar joint.

Ulna and radius parallel each other

Radius cross over the ulna

Cont….

Distally, the head of the ulna articulates with ulna

notch of the radius.

This articulation is the distal radioulnar joint.

Finally, the distal end of the radius articulates

with three bones of the wrist, Lunate, Scaphoid

and the Triquetrum to form radiocarpal joint

(wrist joint).

Muscles of the Elbow

Muscles Move the Elbow Joint

Most of the muscles that move the radius and ulna

cause flexion and extension at elbow joint.

Is a hinge joint.

Muscles of the elbow can divide based on their

action:

– Flexion (flexor muscles)

– Extension (extensor muscles)

– Pronation (pronators muscles)

– Supination (supinators muscles)

Flexor Muscles

Biceps brachii

Brachialis

brachioradialis

Biceps brachii

Origin– Long head – supraglenoid tubercle of scapula.– Short head – coracoid process of scapula

Insertion – radial tuberosity of radius and bicipital aponeurosis

Action– Flexion forearm at elbow joint– Supinates forearm at radioulnar joint– Flexion arm at shoulder joint.

Nerve supply – musculocutaneous nerve

Long Head of Biceps

Short head ofBiceps

Brachialis

Origin – distal, anterior

surface of humerus

Insertion – ulnar tuberosity

and coronoid process of

ulna.

Action - Flexion forearm at

elbow joint

Nerve supply –

musculocutaneous nerve

Brachioradialis

Origin – lateral border of distal end of humerus.

Insertion – superior to styloid process of radius.

Action– Flexion forearm at elbow joint– Supination and pronation

forearm at radioulnar joint. (forearm in neutral position)

Nerve supply – radial nerve

Elbow Flexors

Extensor Muscles of Forearm

Triceps brachii

Anconeus

Triceps brachii

Origin

– Long head – infraglenoid tubercle of scapula

– Lateral head – lateral and posterior surface of

humerus superior to radial groove.

– Medial head – entire posterior surface of humerus

inferior to a radial groove.

Insertion – olecranon of ulna

Action

– Extension forearm

at elbow joint

– Extension arm at

shoulder joint

Nerve supply – radial

nerve

Anconeus

Origin – lateral epicondyle of humerus

Insertion – olecranon and superior portion of shaft of ulna.

Action - Extension forearm at elbow joint

Nerve supply – radial nerve

Triceps Brachii

Pronators Muscles of Forearm

Pronator teres

Pronator quadratus

Pronator teres

Origin – medial epicondyle of humerus and coracoid process of ulna

Insertion – midlateral surface of radius

Action- Pronates forearm at radioulnar joint , Weakly flexes forearm at elbow joint

Nerve supply – median nerve

Pronator quadratus

Orgin – distal portion of shaft of ulna

Insertion – distal portion of shaft of radius\

Action - Pronates forearm at radioulnar joint.

Nerve supply – median nerve

Supinator Muscle of Forearm

Supinator muscles Origin – lateral epicondyle of

humerus and ridge near radial notch of ulna (supinator crest)

Insertion – lateral surface of proximal one-third of radius.

Action - Supinates forearm at radioulnar joints.

Nerve supply – deep radial nerve

Muscles of the Forearm Move the Wrist, Hand, Thumb and Fingers

Group of muscles that act on the digits are

known as extrinsic hand muscles because

originate outside the hand and insert within it.

There is 2 groups of forearm muscles:

– Anterior compartment (flexor muscles)

– Posterior compartment (extensor muscles)

Anterior view of forearm muscles

Anterior compartment of Forearm Muscles

Muscle of the forearm originate on the humerus

Insert on the carpals, metarcarpals, and phalanges

Act as flexor Divide into superficial or deep muscles.

Posterior compartment of Forearm Muscles

Muscle of the forearm originate on the humerus

Insert on the carpals, metarcarpals, and phalanges

Act as extensor Divide into superficial or deep muscles.

Forearm Muscles

Superficial anterior compartment muscles

Deep anterior compartment muscles

Superficial posterior compartment

muscles

Deep posterior compartment muscles

Superficial Anterior Compartment Muscles

Arrange in following order from lateral to medial:

1. Flexor carpi radialis

2. Palmaris longus

3. Flexor carpi ulnaris

4. Flexor digitorum superficialis – deep to the other 3 muscles and is a largest superficial muscle in the forearm.

Deep Anterior Compartment Muscles

Arrange in following order from lateral to medial:

1. Flexor pollicis longus

2. Flexor digitorum profundus

Superficial Posterior Compartment Muscles

Arrange in following order from lateral to

medial:

1. Extensor carpi radialis longus

2. Extensor carpi radialis brevis

3. Extensor digitorum

4. Extensor digiti minimi

5. Extensor carpi ulnaris

Deep Posterior Compartment Muscles

Arrange in following order from lateral to

medial:

1. Abductor pollicis longus

2. Extensor pollicis brevis

3. Extensor pollicis longus

4. Extensor indicis

Elbow Joint

Ulna and radius articulates with the humerus Occurs in 2 place Head of radius articulates with capitulum of

the humerus , and Trochlea of the humerus articulates with

trochlear notch of the ulna.

Elbow Joint

Head of Radius

Trochlear notch

Olecranon

Coronoid Process

Radio-Ulnar Joint (Pivot Joint)

Radius and ulna also articulates with one another in 2 places.

Proximally the head of radius articulates with the radial notch of ulna, a depression that is lateral and inferior to the trochlear notch.

This articulation called proximal radioulnar joint.

Head of radius retain contact with radial notch of ulna by annular ligament.

Distally the head of ulna articulates with ulna notch of the radius.

This articulation is the distal radioulnar joint. the distal end of radius bone articulates with

three bones of the wrist; lunate, scaphoid and the triquetrum to form radiocarpal join.

Radio-Ulnar Joint (Pivot Joint)

Proximal Radio-Ulnar Joint

Head of radius articulate with radial notch of ulna.

Annular Ligament

Distal Radio-Ulnar Joint

Head of ulna articulate with ulnar notch of radius.

Elbow Joint

Hinge joint (one way direction) Articulations between the trochlea of the

humerus with the trochlea notch of ulna and The capitulum of the humerus with the head

of the radius comprise the joint. Movements – flexion and extension of the

forearm

Anatomical Components of Elbow joint

Articular capsule– Consist 2 parts; anterior and posterior parts– Anterior part – covers anterior part of the joint,

from radial and coronoid fossa of the humerus to the coronoid process of the ulna and annular ligament of the radius.

– Posterior part – from capitulum, olecranon fossa, and lateral epicondyle of the humerus to the annular ligament of the radius, olecranon process of ulna and posterior to the radial notch.

Ulnar Collateral Ligament– Thick– Triangular– Extends from the medial epicondyle of the

humerus to the coronoid process and olecranon of the ulna.

Radial Collateral Ligament– Strong– Triangular– Extends from lateral epicondyle of the humerus to

the annular ligaments of the radius and the radial notch of the ulna.

Common Injuries Associated With Elbow

Tennis elbow / Lateral epicondylitis Compression of the ulnar nerve Olecranon bursitis / student’s elbow Golfers / Throwers Elbow (Medial

Epicondylitis) Elbow dislocation

Cubital Fossa

Cubital Fossa

Region of the upper limb in front of the elbow joint

Triangular area with the following boundaries: – laterally, brachioradialis muscle – medially, pronator teres muscle – superiorly, an imaginary line from the medial and

lateral epicondyles.

Cubital Fossa

Bicipital Aponeurosis

Median Nerve

Pronator TeresBrachioradialis

Brachial Artery

Biceps Brachii Tendon

Venous Layer

1 - cephalic vein 2 - basilic vein 3 - median cubital vein

1- bicipital aponeurosis (Grace of God tendon – protect median nerve and brachial artery)

2- biceps tendon

Aponeurotic layer

Artery Nerve Layer

1 - brachial artery 2 - median nerve

Muscular Floor

1 - supinator 2 - brachialis 3 - biceps tendon

Bony Floor

1 - humerus 2 - radius 3 - ulna

Clinical Importance

Phlebotomy – venous blood drainage from median cubital vein

Blood pressure measurement - stethoscope is placed over the brachial artery in the cubital fossa. The brachial pulse may be palpated in the cubital fossa.

Cubital Fossa