X-RAY OF FOREARM
X-ray Forearm A/P View
Forearm AP
Region: ulna, radius bone, carpal joint, elbow joint
Pathology: fracture and bony lesion of ulna and radius bone
SID: 100 cm (40 inches)
Central Ray: perpendicular beam directed at the center of forearm
Respiration: unrelated
Position:
1. The patient is placed in a sitting
position.
2. Lower the shoulder to align shoulder
joint and elbow joint on flat and extend the arm on the image receptor
(IR).
3. Maintaining the supination of the hand, place the center of the forearm at
the center of the IR, and place the forearm tightly to the IR.
4. Lean the shoulder laterally to ensure the entire structure of the forearm is
in the true anteroposterior image.
Collimation: Include all structures from proximal portion of carpal bones to distal portion of elbow joint.
Evaluation:
1.Tuberosity should be observed from
superimposition of the head and neck of the radius
bone with the ulna.
2. Lateral epicondyle and medial epicondyle must be included in the IR.
3. The entire structures of bones interacting with the carpal
bone should be observable in the image.
4. Distal and proximal end of the forearm should have similar densities.
kVp-50, mAs-5
Tip:
1. Place the examining joint on around 5 cm
from tip of IR considering spread of X-ray.
X-ray Forearm Lateral View
Forearm Lateral
Region: ulna, radius bone, carpocarpal joint, elbow joint
Pathology: fracture and bony lesion of ulna and radius bone
SID: 100 cm (40 inches)
Central Ray: perpendicular beam directed at the center of forearm
Respiration: unrelated
Position:
1. The patient is placed in sitting position.
2. Lower the shoulder to place shoulder joint and elbow joint on flat. Place elbow joint on image receptor (IR) in flexion of 90°.
3. Place the center of forearm at the center of IR and attach the forearm tightly to the IR.
4. Immobilize the hand in the true lateral position with thumb side up.
Collimation: Include all structures from proximal portion of carpal bones to distal portion of elbow joint.
Evaluation:
1. The ulnar head must have complete overlap with the radius bone.
2. Lateral epicondyle and medial epicondyle should overlap.
3. Radial head and coronoid process should overlap.
4. Distal and proximal end of the forearm should have similar densities.
kVp-52, mAs-06
Tip:
1. Place the examining joint on around 5 cm from tip of IR considering spread of X-ray.
Anatomy Radius.
The radius is a long bone in the forearm. It lies
laterally and parallel to ulna,
the second of the forearm bones. The radius pivots around the ulna to
produce movement at the proximal and distal radio-ulnar joints.
The radius articulates in four places:
Elbow joint –
Partly formed by an articulation between the head of the radius, and the
capitulum of the humerus.
Proximal
radioulnar joint – An articulation between the radial head, and the
radial notch of the ulna.
Wrist joint –
An articulation between the distal end of the radius and the carpal bones.
Distal radioulnar joint – An articulation between the
ulnar notch and the head of the ulna.
In this article, we shall look at the bony landmarks and
osteological features of the radius.
Fig 1.0 – The anatomical position of the radius.
Proximal Region of the Radius
The proximal end of the radius articulates in both the elbow
and proximal radioulnar joints.
Important bony landmarks include the head, neck and radial
tuberosity:
Head of radius – A disk shaped structure,
with a concave articulating surface. It is thicker medially, where it takes
part in the proximal radioulnar joint.
Neck – A narrow area of bone, which lies between the
radial head and radial tuberosity.
Radial tuberosity – A bony projection, which serves as
the place of attachment of the biceps brachii muscle.
Fig 1.1 – Bony landmarks of the proximal radius.
Shaft of the Radius
The radial shaft expands in diameter as it moves distally.
Much like the ulna, it is triangular in shape, with three borders and
three surfaces.
In the middle of the lateral surface, there is a small
roughening for the attachment of the pronator teres muscle.
Distal Region of the Radius
In the distal region, the radial shaft expands to form a
rectangular end. The lateral side projects distally as the styloid
process. In the medial surface, there is a concavity, called the ulnar
notch, which articulates with the head of ulna, forming the distal radioulnar
joint.
The distal surface of the radius has two facets, for
articulation with the scaphoid and lunate carpal bones.
This makes up the wrist joint.
Fig 1.0 – Articular surfaces of the wrist joint.
Clinical Relevance: Common Fractures of the Radius
The forearm is a common site for bone fractures. Here, we
shall look at the common fracture types involving the radius:
Colles’ fracture – The most common type of radial
fracture. A fall onto an outstretched hand causing a fracture of the distal
radius. The structures distal to the fracture (wrist and hand) are displaced
posteriorly. It produces what is known as the ‘dinner fork deformity’.
Fractures of the radial head – This is
characteristically due to falling on an outstretched hand. The radial head is
forced into the capitulum of humerus, causing it to fracture.
Smith’s fracture – A fracture caused by falling
onto the back of the hand. It is the opposite of a Colles’ fracture, as the
distal fragment is displaced anteriorly.
Fig 1.3 – Colles’ fracture of the wrist. Note the ‘dinner
fork’ deformity, produced by the posterior displacement of the radius.
The radius and the ulna are attached by the interosseous
membrane. The force of a trauma to one bone can be transmitted to the other via
this membrane. Thus, fractures of both the forearm bones are not uncommon.
There are two classical fractures:
Monteggia – usually caused by a force from behind the
ulna. The proximal shaft of ulna is fractured, and the head of the radius
dislocates anteriorly at the elbow.
Galeazzi – a fracture to the distal radius, with the
ulna head dislocating at the distal radio-ulnar joint.
Anatomy ulna
The ulna is a long bone in the forearm. It lies medially and parallel to the radius, the second of the forearm bones. The ulna acts as the stabilising bone, with the radius pivoting to produce movement.
Proximally, the ulna articulates with the humerus at
the elbow joint. Distally, the ulna articulates with the radius, forming
the distal radio-ulnar joint.
In this article, we shall look at the bony landmarks and
osteology of the ulna. We shall also consider its clinical correlations.
Fig 1.0 – Overview of the anatomical position of the ulna in
the upper limb.
Proximal Osteology and Articulation
The proximal end of the ulna articulates with the trochlea of
the humerus. To enable movement at the elbow joint, the ulna has a specialised
structure, with bony prominences for muscle attachment.
Important landmarks of the proximal ulna are
the olecranon, coronoid process, trochlear notch, radial notch and the
tuberosity of ulna:
Olecranon – a large projection of bone
that extends proximally, forming part of trochlear notch. It can be palpated as
the ‘tip’ of the elbow. The triceps brachii muscle attaches to its superior
surface.
Coronoid process – this ridge of
bone projects outwards anteriorly, forming part of the trochlear notch.
Trochlear notch – formed by the olecranon and
coronoid process. It is wrench shaped, and articulates with the trochlea
of the humerus.
Radial notch – located on the lateral surface of
the trochlear notch, this area articulates with the head of the radius.
Tuberosity of ulna – a roughening immediately distal to
the coronoid process. It is where the brachialis muscle attaches.
Fig 1.1 – The bony landmarks of the proximal ulna.
Shaft of the Ulna
The ulnar shaft is triangular in shape, with three
borders and three surfaces. As it moves distally, it decreases in width.
The three surfaces:
Anterior – site of attachment for the pronator
quadratus muscle distally.
Posterior – site of attachment for many muscles.
Medial – unremarkable.
The three borders:
Posterior – palpable along the entire length of the
forearm posteriorly
Interosseous – site of attachment for the interosseous
membrane, which spans the distance between the two forearm bones.
Anterior – unremarkable.
Distal Osteology and Articulations
The distal end of the ulna is much smaller in diameter than
the proximal end. It is mostly unremarkable, terminating in a rounded head,
with distal projection – the ulnar styloid process.
The head articulates with the ulnar notch of the
radius to form the distal
radio-ulnar joint.
Clinical Relevance - Common Fractures of the Ulna
The forearm is a common site for bone fractures. Here, we
shall look at the common fracture types involving the ulna.
Fig 1.2 – Monteggia fracture of the radius and ulna
A fracture of the ulna alone (not involving the radius)
usually occurs as a result of the ulna being hit by an object. The shaft is
the most likely site of fracture. In this situation, the normal muscle tone
will pull the proximal ulna posteriorly.
Less commonly, the olecranon process can be
fractured. This is caused by the patient falling on a flexed elbow. The triceps
brachii can displace part of the fragment proximally.
The ulna and the radius are attached by the interosseous
membrane. The force of a trauma to one bone can be transmitted to the other via
this membrane. Thus, fractures of both the forearm bones are not uncommon.
There are two classical fractures:
Monteggia’s Fracture – Usually caused by a force from
behind the ulna. The proximal shaft of ulna is fractured, and the head of the
radius dislocates anteriorly at the elbow.
Galeazzi’s Fracture – A fracture to the distal radius, with the ulna head dislocating at the distal radio-ulnar joint.
