RT 10 - Chapter 5 (forearm/elbow/humerus)

fat pads

can be visualized only in the lateral projection The posterior fat pad covers the largest area and lies within the olecranon fossa of the posterior humerus. The superimposed coronoid and radial fat pads, which lie in the coronoid and radial fossae of the anterior humerus, form the anterior fat pad. The supinator fat pad is positioned anterior to and parallel with the anterior aspect of the proximal radius. When the elbow is flexed 90 degrees for the lateral projection, only the anterior and supinator fat pads are visible and the posterior fat pad is depressed within the olecranon fossa. The anterior fat pad resembles a teardrop. The fat pads become significant radiographically when an elbow injury causes effusion and displaces the fat pads or alters their shape. Visualization of the posterior fat pad is a reliable indicator of elbow pathology.

which structure articulates with the radius to form the humeroradial joint?

capitulum

forearm

contains two bones that lie parallel to each other -- the radius and the ulna the radius and ulna are long bones. they have a body and two articular extremities the radius is located on the lateral side of the forearm, and the ulna is located on the medial side

which depression is located on the anterior surface of the distal humerus?

coronoid fossa

patient is supine, tube is horizontal, CR entering the right side. IR is next to left side of the body.

dorsal decubitus

describe how radial cross-over occurs when the forearm is demonstrated

during AP projection, the hand is pronated

in which joint is the capitulum located?

elbow

in which joint is the trochlea located?

elbow

exposures for pt. with cast

fiberglass cast - increase mAs 25% or 4 kVp plaster medium cast - increase mAs 50% or 7 kVp plaster large cast - increase mAs 100% or 10 kVp

for the axiolateral projection (Coyle method) of the elbow to demonstrate the coronoid process, the elbow is:

flexed 80 degrees

what is the roughened process of the humerus superior and lateral to the intertubercular groove?

greater tubercle

which bony structures are located on the proximal radius?

head and tuberosity

proximal radioulnar joint

head of radius articulates with radial notch of ulna synovial - pivot

which two structures articulate to form the proximal radioulnar joint?

head of the radius and radial notch of the ulna

which two structures articulate to form the distal radioulnar joint?

head of the ulna and the ulnar notch of the radius

distal radioulnar joint

head of ulna articulates with ulnar notch of radius synovial - pivot

which type of joint is the elbow?

hinge

which articulation do the trochlea and the trochlear notch form?

humeroulnar

which depression is located between the lesser and greater tubercles of the proximal humerus?

intertubercular groove

which projection of the forearm requires that the elbow be flexed 90 degrees?

lateral

with reference from the trochlea, where is the capitulum located?

lateral

which projection of the elbow best demonstrates the olecranon process in profile?

lateral projection

where is the capitulum located?

lateral side of the distal humerus

one way that the lateral image of a humerus, produced with the patient in the lateral decubitus position and the IR placed between the arm and thorax, appears different from the lateral position with the patient standing is that the former demonstrates:

less than the entire humerus

which bony process is located on the anterior surface of the proximal humerus?

lesser tubercle

which projection shows the olecranon process within the olecranon fossa?

medial rotation - AP oblique of elbow

which depression is located on the posterior surface of the distal humerus?

olecranon fossa

which large bony process is easily located by touching on the posterior aspect of the proximal forearm?

olecranon process

with reference to the plane of the IR, how should the humeral epicondylar coronal plane be positioned for the AP projection of the elbow?

parallel

radiocarpal joint

pertaining to the joint between the radius and wrist synovial - ellipsoidal

where is the trochlear notch located?

proximal ulna

which structure articulates with the trochlea?

proximal ulna

which structure articulates with the capitulum?

radial head

which bony structures are located on the proximal end of the ulna?

radial notch, olecranon process, and coronoid process

which structure is located on the lateral aspect of the distal forearm?

radial styloid process

which bones comprise the forearm?

radius and ulna

which bony structure is located on the distal end of the radius?

styloid process

for the AP projection of the forearm, which positioning step should be taken to prevent radial cross-over?

supinate the hand

How should the hand be positioned for the AP projection of the forearm?

supinated

which positioning characteristic best indicates that the humerus is properly positioned for the AP projection of the humerus?

the humeral epicondylar coronal plane is parallel with the IR

with reference to the plane of the IR, how is it determined that the humerus is properly positioned in true lateral position?

the humeral epicondylar coronal plane is perpendicular

which evaluation criterion indicates that the humerus was properly positioned for the AP projection?

the humeral head and greater tubercle are both seen in profile

Which evaluation criterion indicates that the humerus was properly positioned for the lateral projection?

the lesser tubercle is seen in profile

which structure articulates with the ulna to form the humeroulnar joint?

trochlea

humeroulnar joint

trochlea of humerus and trochlear notch of ulna synovial - hinge

which bony structures are located on the distal end of the ulna?

ulnar head and styloid process

which structure is located on the medial side of the distal forearm?

ulnar styloid process

What three anatomical structures form the three concentric arcs on an accurately positioned lateral concentric arcs on an accurately positioned lateral elbow radiograph?

Trochlear sulcus = smallest arc Capitulum and trochlea = 2nd intermediate arc appears double-lined Trochlear notch of the ulna

what is the central ray orientation for the axiolateral projection of the elbow (Coyle method) to demonstrate the coronoid process when the patient is seated?

angled 45 degrees away from the shoulder

humeroradial joint

articulation between the capitulum of the humerus and head of the radius synovial - hinge

what projection should be used to image the radial head on a trauma patient?

axiolateral projection (Coyle method) of elbow joint

AP elbow

- CR: perpendicular to the elbow joint - collimate field to 3 in (8cm) proximal and distal to the elbow joint and 1 in (2.5cm) on the sides structures shown: an AP projection of the elbow joint, distal arm, and proximal forearm

AP oblique elbow medial rotation

- CR: perpendicular to the elbow joint - collimate field to 3 in (8cm) proximal and distal to the elbow joint and 1 in (2.5cm) on the sides structures shown: an oblique projection of the elbow with the coronoid process projected free of superimposition

AP oblique elbow lateral rotation

- CR: perpendicular to the elbow joint - collimate field to 3 in (8cm) proximal and distal to the elbow joint and 1 in (2.5cm) on the sides structures shown: an oblique projection of the elbow with the radial head and neck projected free of superimposition of the ulna

Lateral elbow

- CR: perpendicular to the elbow joint regardless of its location on IR - collimate field to 3 in (8cm) proximal and distal to the elbow joint structures shown: lateral projection shows the elbow joint, distal arm, proximal forearm

AP forearm

- CR: perpendicular to the midpoint of the forearm - collimate field to 2 in (5cm) distal to the wrist joint and proximal to the elbow joint and 1 in (2.5cm) on the sides structures shown: the elbow joint, the radius and ulna, and the proximal row of slightly distorted carpal bones

Lateral forearm

- CR: perpendicular to the midpoint of the forearm - collimate field to 2 in (5cm) distal to the wrist joint and proximal to the elbow joint, and 1 in (2.5cm) on the sides structures shown: the elbow joint, the radius and ulna, and the proximal row of superimposed carpal bones

AP humerus recumbent

- CR: perpendicular to the midportion of the humerus and center of IR - collimate field to 2 in (5cm) distal to the elbow joint and superior to the shoulder and 1 in (2.5cm) on the sides structures shown: AP projection shows the entire length of the humerus. the accuracy of the position is shown by the epicondyles

Lateral humerus recumbent

- CR: perpendicular to the midportion of the humerus and the center of the IR - collimate field to 2 in (5cm) distal to the elbow joint and superior to the shoulder and 1 in (2.5cm) on the sides structures shown: lateral projection shows the entire length of the humerus. a true lateral image is confirmed by superimposed epicondyles

how many articulations does the humerus have?

3

what is the direction and amount of central ray angulation for the axiolateral projection (Coyle method) to demonstrate the radial head and capitulum?

45 degrees toward the shoulder

how much should the elbow be flexed for the lateral projection of the elbow?

90 degrees

which projection and position of the upper extremity best demonstrates the coronoid process in profile and free of superimposition?

AP oblique of the elbow in medial rotation

which projection of the elbow best demonstrates the radial head free of bony superimposition?

AP oblique, lateral rotation position

humerus

The arm has one bone called the humerus, which consists of a body and two articular ends. The proximal part of the humerus articulates with the shoulder girdle. The distal humerus is broad and flattened and presents numerous processes and depressions. The entire distal end of the humerus is called the humeral condyle and includes two smooth elevations for articulation with the bones of the forearm—the trochlea on the medial side and the capitulum on the lateral side. The medial and lateral epicondyles are superior to the condyle and are easily palpated. On the anterior surface superior to the trochlea, a shallow depression called the coronoid fossa receives the coronoid process when the elbow is flexed. The relatively small radial fossa, which receives the radial head when the elbow is flexed, is located lateral to the coronoid fossa and proximal to the capitulum. The olecranon fossa is a deep depression found immediately behind the coronoid fossa on the posterior surface and accommodates the olecranon process when the elbow is extended. The proximal end of the humerus contains the head, which is large, smooth, and rounded and lies in an oblique plane on the superomedial side. Just below the head, lying in the same oblique plane, is the narrow, constricted anatomic neck. The constriction of the body just below the tubercles is called the surgical neck, which is the site of many fractures. The lesser tubercle is situated on the anterior surface of the bone immediately below the anatomic neck. The tendon of the subscapularis muscle inserts at the lesser tubercle. The greater tubercle is located on the lateral surface of the bone just below the anatomic neck and is separated from the lesser tubercle by a deep depression called the intertubercular groove.

ulna

The body of the ulna is long and slender and tapers inferiorly. The upper portion of the ulna is large and presents two beaklike processes and concave depressions. The proximal process, or olecranon process, concaves anteriorly and slightly inferiorly and forms the proximal portion of the trochlear notch. The more distal coronoid process projects anteriorly from the anterior surface of the body and curves slightly superiorly. The process is triangular and forms the lower portion of the trochlear notch. A depression called the radial notch is located on the lateral aspect of the coronoid process. The distal end of the ulna includes a rounded process on its lateral side called the head and a narrower conic projection on the posteromedial side called the ulnar styloid process. An articular disk separates the head of the ulna from the wrist joint.

radius

The proximal end of the radius is small and presents a flat disk-like head above a constricted area called the neck. Just inferior to the neck on the medial side of the body of the radius is a roughened process called the radial tuberosity. The distal end of the radius is broad and flattened and has a conic projection on its lateral surface called the radial styloid process.