Anatomy of the Distal Humerus and Elbow Joint

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Questions and Answers

Which fat pad is typically visible on a lateral elbow projection?

Supinator fat stripe

Anterior fat pad (correct)

Distal fat stripe

Posterior fat pad

In which position is the proximal radius and ulna completely superimposed?

Lateral Oblique

Medial Oblique (correct)

Distal Oblique

What can the supinator fat stripe indicate?

Inflammation of the bursae

Infection of bone marrow

Fractures that are easily seen

Radial head or neck fractures not easily seen (correct)

Which condition is characterized by abnormally dense bone and often referred to as 'marble bone'?

Osteopetrosis Signup and view all the answers

What is the typical cause of osteomyelitis?

Infection by bacteria due to trauma or surgery Signup and view all the answers

Which projection best demonstrates the radial head and neck as well as the capitulum of the humerus?

Lateral oblique elbow projection Signup and view all the answers

What is the standard CR location for an AP elbow projection?

At the midpoint of the elbow joint Signup and view all the answers

How many degrees should the elbow be rotated for an external (lateral) oblique elbow projection?

45 degrees Signup and view all the answers

What is the proper hand position for a medial (internal) AP oblique elbow projection?

Supinated Signup and view all the answers

Which Coyle method requires the hand to be pronated?

Axial lateromedial projection Signup and view all the answers

Which clinical indication is appropriate for using the Axial Lateromedial Projection of the elbow?

Fractures and dislocations of the radial head Signup and view all the answers

What is the recommended angle for the central ray when performing the Axial Mediolateral Projection?

45 degrees towards the shoulder Signup and view all the answers

What is the primary visual objective of the Axial Lateromedial Projection?

Radial head Signup and view all the answers

In preparing for the Radial Head Laterals, how should the arm be positioned?

Flexed 90 degrees Signup and view all the answers

What structure does the trochlea of the humerus directly articulate with?

Proximal ulna Signup and view all the answers

Which evaluation criterion is key for the Axial Mediolateral Projection?

Anterior portion of the coronoid appears elongated in profile Signup and view all the answers

Which fossa on the humerus receives the radial head?

Radial fossa Signup and view all the answers

What is an essential factor for the Axial Lateromedial Projection when positioning the elbow?

Elbow flexed at 90 degrees Signup and view all the answers

What clinical indications warrant an AP projection of the elbow?

Fractures and dislocations of the elbow Signup and view all the answers

In which scenario should a partial flexion AP projection be used?

When the elbow cannot be fully extended Signup and view all the answers

What is the essential beam direction for an AP projection of the elbow?

Perpendicular to the image receptor Signup and view all the answers

How should the arm be positioned for a lateral oblique projection of the elbow?

Arm fully extended and hand supinated with lateral rotation Signup and view all the answers

Which anatomical structures are best visualized with a lateral projection of the elbow?

Capitulum and radial head Signup and view all the answers

What is the recommended Source to Image Distance (SID) for elbow projections?

40 inches Signup and view all the answers

When setting up for an elbow projection, how should the forearm and humerus be aligned?

On the same plane Signup and view all the answers

What is the primary purpose of performing two projections during elbow radiography?

To view different angles of the elbow Signup and view all the answers

Which part of the humerus articulates with the ulna?

Trochlea Signup and view all the answers

What does the lateral epicondyle of the humerus represent?

A small projection on the lateral aspect Signup and view all the answers

What anatomical feature receives the coronoid process?

Coronoid fossa Signup and view all the answers

In a true lateral elbow image, which arcs should be evaluated?

Three concentric arcs Signup and view all the answers

Which depression of the distal humerus is located more laterally?

Radial fossa Signup and view all the answers

What occurs when the arm is fully extended in relation to the olecranon fossa?

Receives the olecranon process of the ulna Signup and view all the answers

What is the significance of the trochlear sulcus in elbow imaging?

It appears as a less dense area on lateral views. Signup and view all the answers

Which projection of the elbow may be requested to better visualize the radial head?

Oblique projection Signup and view all the answers

Which part of the humerus is referred to as 'the little head'?

Capitulum Signup and view all the answers

What anatomical structure is located on the medial edge of the distal humerus?

Medial epicondyle Signup and view all the answers

Study Notes

Distal Humerus

The expanded distal end of the humerus is called the humeral condyle.
The medial condyle articulates with the ulna and is shaped like a pulley.
The medial condyle contains a smooth depressed center called the trochlear sulcus.
The lateral condyle, referred to as the capitulum, articulates with the radial head.
The lateral epicondyle, a small projection located above the capitulum, is smaller than the medial epicondyle.
The medial epicondyle, located on the medial edge of the distal humerus, is larger and more prominent than the lateral epicondyle.
The coronoid fossa is an anterior depression that receives the coronoid process.
The radial fossa, an anterior depression, is located lateral to the coronoid fossa and receives the radial head.
The olecranon fossa, located posteriorly, receives the olecranon process when the arm is fully extended.

Elbow Joints

The olecranon fossa is one of the structures that form the elbow joint.
The proximal radioulnar joint is another joint that is located near the elbow.

Fat Pads

The anterior fat pad is visible on the lateral elbow projection.
Posterior fat pads are not typically visible on X-rays unless there is trauma or incorrect flexion.
The supinator fat stripe may indicate a radial head or neck fracture.

Positioning Considerations

The standard SID for elbow projections is 40 inches.
Remove all artifacts or jewelry from the patient before radiographic procedures.
Keep the shoulder and upper extremity on the same plane when positioning.

Routine Projections

Common routine projections for the elbow include:
- AP
- Alternate AP – Partial Flexion
- Lateral (external)
- Medial (internal) Oblique
- Lateral Oblique

AP Projection

Clinical Indications: Fractures, dislocations, osteomyelitis, and arthritis.
The elbow should be fully extended with the hands supinated.
The patient may need to lean laterally for a true AP projection.
The epicondyles should be parallel to the IR.
CR is perpendicular to the IR and directed at the mid-elbow joint (3/4 inch distal to the midpoint of the epicondyles).

Alternate AP – Partial Flexion

Clinical Indications: Fractures, dislocations, osteomyelitis and arthritis.
Used when the elbow cannot be fully extended.
Two projections are needed:
- One with the forearm parallel to the IR.
- One with the humerus parallel to the IR.
CR: Perpendicular to the IR, directed at the mid-elbow joint.

Lateral (External) Oblique Projection

Clinical Indications: Fractures and dislocations, primarily those involving the radial head and neck.
Best visualizes the radial head and neck of the radius and capitulum of the humerus.
Arm should be fully extended and on the same plane as the shoulder.
Hand should be supinated and rotated laterally approximately 45 degrees.
CR is directed at the mid-elbow joint.
Evaluation Criteria: The radial head, neck, and tuberosity should not be superimposed by the ulna.

Trauma Axial Laterals (Coyle Methods)

Clinical Indications: Fractures and dislocations, particularly when the elbow cannot be fully extended for medial and lateral oblique projections.
Two projections are used:
- Axial Lateromedial Projection (radial head best visualized)
- Axial Mediolateral Projection (Coronoid process best visualized)

Axial Lateromedial Projection (Radial Head)

Clinical Indications: Fractures and dislocations of the radial head.
Elbow should be flexed 90 degrees if possible.
Hand should be pronated.
CR angled 45 degrees toward the shoulder, centered at the radial head and mid-elbow joint.
Evaluation Criteria: The joint space between the radial head and capitulum should be open, and the radial head, neck, and tuberosity should be free of superimposition.

Axial Mediolateral Projection (Coronoid Process)

Clinical Indications: Fractures and dislocations involving the coronoid process.
Elbow should be flexed to 80 degrees, hand pronated.
CR angled 45 degrees from the shoulder, into the mid-elbow joint.
Evaluation Criteria: The anterior portion of the coronoid process is elongated in profile, the joint space between the coronoid process and trochlea should be open, and the radial head and neck should be superimposed by the ulna.

Radial Head Laterals (Coyle Method)

Clinical Indications: Occult fractures of the radial head or neck.
Elbow flexed 90 degrees.
Upper extremity and shoulder remain on the same plane.
Four projections are obtained:
- Supinate hand and externally rotate as far as tolerated.
- Place hand in true lateral position.
- Pronate hand.
- Internally rotate hand as far as tolerated.
CR perpendicular to the IR, directed at the radial head.
Evaluation Criteria: The radial tuberosity should be visualized in different positions, depending on the rotation of the hand.

Common Pathologies

Osteomyelitis: Infection of the bone or bone marrow, often caused by bacteria and associated with trauma or surgery.
Bursitis: Inflammation of the bursae, fluid-filled sacs located around joints, resulting in pain and limited range of motion.
Osteopetrosis: Rare genetic disorder characterized by abnormally dense bone, often referred to as "marble bone."

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Description

This quiz explores the detailed anatomy of the distal humerus and its role in the elbow joint. It covers features such as the humeral condyle, epicondyles, and various fossae that contribute to joint movement. Test your understanding of these critical anatomical structures!