Forearm and Humerus Flashcards
In an AP forearm what should be parallel and in profile at extreme medial and lateral edges of distal humerus
Medial and lateral epicondyles
What is in profile in an AP forearm
The radial styloid is in profile.
Radial tuberosity in profile medially
In an AP, what is superimposed over the lateral aspect of the ulna by about ¼ inch
The radial head
How much does the radial head superimpose over the ulna in an AP forearm
about 1/4 inch
Use of anode- heel effect
what body part is at which side
Wrist at anode side
elbow at cathode side
For an AP forearm what should be included
Both joints on IR. The IR should extend one inch beyond wrist and elbow
What joint is partially or completely closed in an AP forearm
An partial or completely closed capitulum -radial joint
if the forearm is rotated externally in an AP forearm what MC’s are superimposed
4th and 5th
when there is rotation in an ap forearm what is no longer in profile
radial styloid
In an AP, what rotation occurs from inaccurate positioning of the hand and wrist
Distal forearm
what should you use to determine rotation of an ap forearm
MC’s
if the 1st and 2nd MC are superimposed what kind of rotation is it
Internal rotation( pisiform and hamate hook are better demonstrated)
what are superimposed if there is rotation of an ap forearm
Distal radius and ulna and MC bases are superimposed
Pt. with known or suspected fractures
If they are unable to place arm in position, what should you do
position the area closest to the fracture in a true position
Proximal forearm rotation is due to :
poorly positioned humeral epicondyles
When more than ¼ of head is over ulna, how is the elbow rotated?
the elbow is internally rotated (medially)
When less than ¼ of head is over ulna, how is the elbow rotated
the elbow is externally rotated (laterally)
when does the Radial head demonstrates more or less than ¼ superimposition on ulna
when the proximal forearm is rotated internally or externally
what causes the radioscaphoid and radiolunate joint spaces to be open in the AP projection when CR is at the midfoream
Due to a diverged x-ray beam
how much of each joint should be on the image for a lateral forearm
IR long enough to extend one inch beyond both joint spaces
how should the elbow, humerus, hand, and wrist be positioned for a lateral forearm
- elbow in lateral position
-humerus same horizontal plane - hand and wrist in lateral position
what should be in profile in a lateral forearm
ulnar styloid in profile
how is the distal scaphoid in the lateral forearm
The distal scaphoid slightly distal to the pisiform and anterior to the capitate and lunate
where is the most common place for avulsion fracture
ulnar styloid process
where can you see floud build up, effussion or fractures
pronator, supinator, or anterior fat pad
what the most common to cut off in an lateral forearm
olecranon
why is there a open elbow joint space in a lateral forearm
divergence of the beam
how is the posterior fat pad if its not injured
it goes into the olecranon and you wont see it
how is the posterior fat pad if there is an injury
you will see it
what is the soft tissues of interest in a lateral forearm
Soft tissues of interest are the anterior and posterior fat pads and the supinator fat stripe at the elbow
how is the pronator fat stripe located
The pronator fat stripe is located anterior surface of the distal radius
The posterior fat pad is pushed out with injury, what does it do to the olecranon
pushing proximal and posterior to the olecranon process
If there is distal external (supinated) wrist rotation how is the pisiform
anterior to the distal scaphoid
If there is distal external (supinated) wrist rotation how is the ulna
ulna appears anterior to the radius
if the hand is pronated for a forearm, how is the distal scaphoid
distal scaphoid is anterior to the pisiform and the radius is anterior to the ulna
if the hand is pronated for a forearm how is the radius
radius is anterior to the ulna
in external rotation what happens to pisiform
push pisiform out, becoming more anterior
what can displace the fat pads
poor elbow placement
in rotation of the forearm if the elbow is still lateral how is the radial tuberosity facing ?
anteriorly
for a lateral forearm if the proximal forearm is elevated how is the capitulum and trochlea positioned
capitulum- too far anteriorly
medial trochlea - too posteriorly
resulting in closing the elbow joint space
this position results in the capitulum and medial trochlea misalignment and also the radial head and coronoid process
poor humeral position
how is the radial head when the proximal humerus is elevated
The radial head is positioned posterior to the coronoid process
how are the medial and lateral humeral epicondyles in a AP humerus
Medial and lateral humeral epicondyles are in profile ( parallel with the IR
how much are the radial head and tuberosity superimposed over the lateral aspect of the proximal ulna
1/4 inch
what is demonstrated in profile laterally in a AP humerus
greater tubercle
what is demonstrated in medial profile in an AP humerus
Humeral head is demonstrated in medial profile
what is visible halfway between greater tubercle and humeral head
Vertical cortical margin of lesser tubercle
what aligns with thumb
greater tubercle
what should be parallel in an AP humerus
epicondyles
how is the radial tuberosity when the hand is supinated in AP humerus
medial
how will you determine amt of rotation needed
Determine amount of rotation needed by looking at the radial tuberosity superimposition of the ulna
what is a result of poor humeral epicondyle positioning
rotation of humerus as a result of poor humeral epicondyle positioning
if there is less than 1/4 of radius and ulna overlapping, what is the rotation
external (laterally)
if there is more than 1/4 inch of the tuberosity is shown on ulna , how is the rotation
If more than ¼ inch of the tuberosity is shown on ulna, the elbow and humerus as been medially rotated
what can excessive rotating due of there is a fracture of the humerus
When a fracture is suspected or follow-up image is taken the forearm should not be externally rotated excessively , this may cause an increase risk of RADIAL NERVE DAMAGE
how should you position someone with an injury that is unable to move
Joint closest to the injury should be aligned in the true AP position
how is the lesser tubercle in a Mediolateral Humerus
Lesser tubercle is in profile medially and the humeral head and greater tubercle are superimposed
how is the humeral head and greater tubercle in a mediolateral humerus
humeral head and greater tubercle are superimposed
how is the radial head demonstrated in the mediolateral humerus
Mediolateral projection most of the radial head is demonstrated anterior to the coronoid process,
radial tuberosity is in profile
how is the radial tuberosity in the mediolateral humerus
in profile
how are the epicondyles in the mediolateral humerus
Epicondyles are perpendicular to IR
out of mediolateral humerus and lateromedial which one decreases distorition
mediolateral
what is seen better in mediolateral humerus
radial head
what is better in the lateromedial humerus
coronoid
what happens when there is over rotation of the mediolateral projection of the humerus
If there is to much rotation of the patient (pt. is no longer in a PA position)
This would cause a decrease in density of the proximal humerus compared to the distal humerus
how are the epicondyles in a lateromedial humerus
perp to ir
for a good lateral elbow in a lateral humerus how should the hand be
turned up
in this view, the radial head and coronoid process are superimposed, the radial tuberosity is not in profile and the capitulum is visible distal to the medial trochlea
Lateromedial Humerus
what are superimposed in a lateromedial humerus
radial head and coronoid process are superimposed,
how is the capitulum in a lateromedial
capitulum is visible distal to the medial trochlea
what two ways can you do the proximal humerus
scapular y and transthoracic
use a 3 second breathing technique, proximal humerus is halfway between the sternum and the thoracic vertebrae
Transthoracic lateral position
is this internal rotation or external
-radial tuberosity more than 1/4 inch over ulna
-MC are not flat
more superimposition on the bases than others
-see pisiform - hand rotated internally
- radial styloid out of profile
- MC bases superimposed
-pisiform our by itself
what are some indications of internal rotation of a forearm
-radial tuberosity more than 1/4 inch over ulna
-MC are not flat
more superimposition on the bases than others
-see pisiform - hand rotated internally
- radial styloid out of profile
- MC bases superimposed
-pisiform our by itself
how should the anterior fat pad look like
a tear drop
if anterior fat pad is not in proper position what does that indicate
indication of a radial head fracture
in a forearm, if the pisiform is more anterior than scaphoid , how is the hand
- hand supinated
- externally rotated
in a forearm, if the scaphoid is more anterior how is it rotated and how is the hand
-hand pronated
-internally rotated
when the proximal forearm is elevated how is the capitulum
too anterior
if the capitulum is anterior in a forearm how is the trochlea
posterior
if there is poor humeral position and the radial head is anterior how is the capitulum, ulna, and trochlea
radial head anterior (more over on ulna)
capitulum distally
ulna posterior
trochlea superior or proximal
how should the hand be in an AP humerus
pronated
in an AP humuerus, how should the lesser be?
lesser half way between greater and humeral head
