Elbow and Forearm Anatomy: Ulna, Radius, and Joint Structures

The ulnar notch is located at the

Medial aspect of the distal radius

Which of the following structures is located on the distal humerus

Capitulum

The distal radius will cross over the ulna when the hand is pronated

False

Which of the following is found on the distal ulna

Ulnar head

Which part of the distal humerus articulates and fits into the semilunar notch of the ulna

Trochlea

Name the three concentric circles of the elbow joint from smallest to largest

Trochlear sulcus then overlapping trochlea and capitulum then trochlear notch

What movement do the proximal and distal radioulnar joints have

Trochoid or pivot

What condyle of the humerus articulates with the radial head

Capitulum

How many views are required for a routine elbow with pain but no trauma

Two (AP and lateral)

How many views are required for a trauma elbow

Four (AP, both obliques, and lateral)

When are Coyles and partial flexion/full flexion views used

During trauma exams

Which type of patients are imaged "as is" when they can't move

Ortho/casted patients

Which bone forms the wrist joint

Radius

Which bone forms most of the elbow joint

Ulna

Which bone is slightly anterior at the proximal end

Radius

What are the joints between radius and ulna called

Proximal and distal radioulnar joints

What movement do these joints allow

Rotation of the radius around the ulna

When the hand moves from supination to pronation which bone crosses over

Radius

During pronation which third of the radius crosses the ulna

Proximal one-third

When pronated or supinated the distal radius and ulna remain

Parallel

Which part of the ulna forms the tip of the elbow

Olecranon process

What notch of the ulna holds the trochlea of the humerus

Trochlear semilunar notch

What joint is formed by the radial head articulating with the ulna

Proximal radioulnar joint

Where is the radial notch found

On the lateral side of the ulna

What does the radial notch articulate with

The head of the radius

What part of the ulna is the anterior point of the trochlear notch

Coronoid process

What small ridge extends medially from the coronoid process

Coronoid tubercle

Which projection best shows the coronoid tubercle

AP forearm

What is the function of the coronoid process

Helps with elbow joint articulation

What is the function of the coronoid tubercle

Anchors ligaments in the elbow

What portion connects the two ends of the ulna

Body or shaft

What structures are palpable on the ulna

Olecranon process and styloid process

What forms the distal radioulnar joint

Ulnar head and ulnar notch of radius

What part of the radius articulates with the ulna

Head proximally and ulnar notch distally

What part of the radius fits into the radial notch

Radial head

What part of the radius is slightly narrowed below the head

Neck

What is located just below the neck on the radius

Radial tuberosity

Where is the radial tuberosity located

Anterior and medial on proximal radius

When can the radial tuberosity be hidden radiographically

In lateral elbow position or with pronation

What is the distal articulation on the radius

Ulnar notch

What process is found at the distal end of the radius

Radial styloid process

Which styloid process extends farther distally

Radial styloid process

Which styloid process is palpable

Radial styloid process

Which structures are palpable on the distal humerus

Medial and lateral epicondyles

Which structures are NOT palpable on the distal humerus

The condyles (trochlea and capitulum)

What are the two condyles of the humerus

Trochlea (medial) and capitulum (lateral)

Which condyle articulates with the ulna

Trochlea

Which condyle articulates with the radius

Capitulum

What is the narrow middle of the trochlea called

Trochlear sulcus

What are the three fossae on the distal humerus

Radial fossa, coronoid fossa, olecranon fossa

What fits into the olecranon fossa during extension

Olecranon process

What fits into the coronoid fossa during flexion

Coronoid process

What fits into the radial fossa during flexion

Radial head

Which fossae are anterior on the humerus

Radial and coronoid fossae

Which fossa is posterior

Olecranon fossa

Which structure is visible radiographically on a lateral elbow

Trochlear sulcus

How should AP forearms be hung

From the fingertips (ballerina view)

How are the radius and ulna in a true AP position

Parallel

How should lateral forearms be hung

From the fingertips (thumb side up)

How many degrees must the elbow be flexed for a lateral

90 degrees

What must the wrist, elbow, and shoulder share in a lateral,

Same plane (same height)

If the joints are not on the same plane what happens,

Anatomy will be distorted and joint spaces closed

What is best seen on a lateral elbow

Olecranon process

What additional structures can be seen well on a lateral elbow

Trochlear notch and coronoid process

Name the three concentric circles from smallest to largest

Trochlear sulcus, overlapping trochlea and capitulum, trochlear notch

If the capitulum moves out of alignment with the other circles, what does that indicate,

Positioning error

What angle should the arm be for an external oblique elbow

45 degrees lateral rotation

What is best seen on an external oblique elbow

Radial head, neck, and tuberosity and capitulum

What angle should the arm be for an internal oblique elbow

45 degrees medial rotation

What is best seen on an internal oblique elbow

Coronoid process and trochlea

What is best seen on an AP elbow

Coronoid tubercle and epicondyles parallel to IR

How many fat pads are found at the elbow

Three

Name the elbow fat pads

Anterior, posterior, supinator

Where is the anterior fat pad located

Anterior to distal humerus

Where is the posterior fat pad located

Posterior to distal humerus inside olecranon fossa

Where is the supinator fat pad located

Anterior to proximal radius

Which fat pad is always visible

Supinator

Which fat pad is only visible when there is trauma

Posterior

Why does the posterior fat pad become visible

Swelling or fluid pushes it out of the olecranon fossa

Which fat pad is associated with the wrist instead of elbow

Pronator (in wrist imaged prone)

What type of joint is the elbow

Synovial diarthrodial hinge (ginglymus)

What is the movement type of the humeroulnar and humeroradial joints

Hinge (ginglymus)

What is the movement type of proximal and distal radioulnar joints

Trochoid/pivot

Why should forearm and elbow not be radiographed PA

Because pronation causes the radius to cross over the ulna

When pronated, what part of the radius crosses over the ulna

Proximal one-third

Why do ortho clinics sometimes use PA forearms

To match the position of the patient's cast

What indicates flexion on an AP elbow

Visible olecranon fossa

When fully extended can you see the olecranon fossa,

No

What causes the olecranon process to appear translucent

Slight flexion

In a lateral elbow what do the epicondyles and condyles do,

Superimpose on one another

What structure appears as three concentric circles in a lateral elbow

Trochlear sulcus, trochlea/capitulum, and trochlear notch

What error causes the capitulum to shift

Unequal plane height between wrist, elbow, or shoulder

What phrase helps remember the capitulum location

Radial head wears a cap

What phrase helps remember radius vs ulna

Repost or retweet with your radius (thumb side)

What does "funny bone" refer to

Olecranon process (ulnar nerve runs near it)

Which part of the ulna is most proximal

Olecranon process

Which styloid process extends farther distally

Radial styloid process

Which part of the humerus has the trochlear sulcus

Medial condyle (trochlea)

Trochlear notch is located on which bone

U

Radial notch is located on which bone

U