Distal Humerus and Elbow

What is the condyle of the humerus?

the expanded distal end

What are the sharp edges of the humerus above the condyle called?

supracondylar ridges

What are the epicondyles?

rough projections on either side of the distal end of the humerus for forearm muscle attachments

What is the difference between the medial and lateral epicondyles?

medial is larger and more easily palpated

What is the capitulum?

rounded knob on the lateral aspect of the humerus that articulates with the head of the radius

forms the humeroradial joint

What is the humeroradial joint?

diarthrodial, synovial, hinge joint made up of the capitulum and radial head

What is the trochlea?

spool-like surface on the medial aspect of the humerus that articulates with the ulna

forms the humeroulnar joint

What is the humeroulnar joint?

diarthrodial, synovial, hinge joint made up of the trochlea and ulna

What is the trochlear sulcus?

the central concave depression on the articular surface of the distal humerus where the ulna articulates

What is the coronoid fossa?

anterior depression on the humerus (receives the coronoid process of the ulna when the arm is flexed)

What is the radial fossa?

depression in the humerus lateral to the coronoid fossa (receives the radius when the arm is flexed)

What is the olecranon fossa?

depression on the posterior distal humerus, triangular in shape, receives the olecranon when the arm is extended

What are the Joints that make up the Elbow Joint Proper

made up of 3 joints

1. Humeroulnar Joint

   1. Synovial, Diarthrodial, Hinge/Ginglymus

2. Humeroradial Joint

   1. Synovial, Diarthrodial, Hinge/Ginglymus

3. Proximal Radioulnar Joint

   1. Synovial, Diarthrodial, Pivot/Trochoid

When are the fat pads of the elbow visualized?

in a true lateral view of the elbow

What is shown by the arrow?

anterior fat pad

What is shown by the arrow?

posterior fat pad

What is shown by the arrows?

supinator fat stripe

Which fat pad is only seen when there is an injury?

posterior

What is a routine elbow?

AP, internal/medial oblique, external/lateral oblique, lateral

Explain the AP elbow image

• arm extended with hand supinated

• epicondyles parallel to IR

• slight superimposition of proximal radius and ulna

How are elbow images sent?

as if someone is standing in front of you in anatomical position

Based solely on how the image was oriented when sent, is this a right or a left elbow?

right

What are A, B, and C in this image?

A: medial epicondyle

B: lateral epicondyle

C: olecranon

Explain the internal AP oblique image

• arm rotated medially with hand pronated

• medial epicondyle in contact with IR, lateral epicondyle 45^o up

• coronoid process in profile

• superimposition of the proximal radius and ulna

What projection was taken to obtain this image? R or L?

right elbow, internal AP oblique

Explain the external AP oblique image

• arm rotated laterally

• lateral epicondyle in contact with IR, medial epicondyle 45^o up

• radial head free of superimposition

• radial tuberosity free of superimposition

What projection was taken to obtain this image? R or L?

right elbow, external AP oblique

Explain the lateral elbow image

• 90^o flexion, true lateral

• lateromedial projection

• superimposed epicondyles (perpendicular to IR)

• hand in lateral position

  • this places radial tuberosity anterior

List the 3 concentric arcs visible on a lateral elbow image (in order from middle circle to outermost circle)

1. trochlear sulcus

2. superimposed capitulum and trochlea

3. trochlear notch

Explain the supracondylar fracture

• most common fracture in children

• occurs through the growth plate of the humerus

• caused by falling on an outstretched arm

Explain the olecranon fracture

a fracture of the olecranon; makes up 10% of elbow fractures

What kind of pathology is shown in the image?

supracondylar fracture

What kind of pathology is shown in the image?

olecranon fracture

What kind of pathology is shown in the image?

complete dislocation

What kind of pathology is shown in the image?

partial dislocation

Explain the radial head fracture

• caused by a fall on an outstretched arm

• most common elbow fracture in adults (30%)

• can be subtle and hard to see on an x-ray

• best demonstrated on external oblique