Upper Limb - Ch 5

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4 groups of upper limb

1. hand and wrist
2. forearm
3. arm (humerus)
4. shoulder girdle

Hand and wrist

27 bones in each:
14 phalanges (fingers and thumb)
5 metacarpals (palm)
8 carpals (wrist)

Phalanges

Most distal bones of the hand

Metacarpals

make up the palm

Carpals

bones of the wrist

digit

each finger and thumb;consists of 2 or 3 separate small bones called phalanges (singular = phalanx)

number of the digits

thumb starts at 1

Each of the four fingers is composed of

Proximal, middle and distal phalanges

The thumb is composed of

2 phalanges, the proximal and distal.

Each phalanx has X number of parts

3 parts to each phalanx:
head - distal rounded part
body - shaft
base - most proximal part

Each metacarpal has # number of parts

3 parts - metacarpals:
head - distal rounded part
body - shaft - rounded part. Anterior is concave, posterior is convex
base - most proximal part - articulates with carpals

Articulations

joints

Small chip fractures may occur near the

joint spaces.

Interphalangeal joint (IP)

The thumb's joint between the 2 phalanges

metacarpophalangeal (MCP) joint

the joint b/w the head of the metacarpal and the base of the proximal phalanx

The first metacarpal is considered

part of the thumb and must be included in a radiograph of the thumb. Not so with the other 4 fingers(include only the 3 phalanges).

distal interphalangeal (DIP) joint

joint between the distal and middle phalanges

proximal interphalangeal (PIP) joint

joint between the middle and proximal phalanges

carpometacarpal (CMC) joints

articulate at the metacarpal's proximal end with the carpals

The metacarpals articulate with specific carpals

First MC with trapezium
2nd MC with trapezoid
3rd MC with capitate
4th and 5th MC with hamate

Scaphoid (navicular) bone

on thumb side. boat-shaped. Largest in the proximal row - articulates with the radius proximally. Most frequently fractured carpal bone. AKA navicular

Lunate

2nd in the proximal row of carpals. Articulates with the radius. Deep concavity on distal surface where it articulates with the capitate. AKA semilunar.

Most often fractured carpal

the scaphoid

triquetrum

3rd carpal in the proximal row of carpals. Has 3 articular surfaces and has a pyramidal shape and anterior articulation with the small pisiform. AKA triquetral, triangular, or cuneiform

pisiform

4th carpal in the proximal row of carpals. Smallest of the carpals. Located anterior to the triquetrum. Most evident in the carpal sulcus view. Means pea-shaped

Trapezium

1st in the distal row of carpals. 4-sided irregular bone, medial and distal to the scaphod. AKA lesser multangular

trapezoid

2nd in the distal row of carpals. Another 4-sided bone, smallest one in the distal row. AKA lesser multangular

Capitate

3rd in the distal row of carpals. Means "large bone". Large rounded head that fits prximally into a concavity formed by the scaphoid and lunate bones. AKA os magnum.

Hamate

4th in the distal row of carpals. Hook shaped process called the hamulus or hamular process. Unciform

Hamulus/hamular process

Hook shaped process of the hamate bone

Carpal sulcus

Groove (concave area) through with major nerves and tendons pass. tangential view - formed by concave anterior or palmar aspect of the carpals. Best view to visualize the pisiform and hamate's hamulus. Also can easily view the trapezium and its relations to the thumb and trapezoid.

Mnemonic for carpals

Steve left the party to take Carol home.
Scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, hamate.

lateral position shows

the trapezium and scaphoid are located more anteriorly.

radial deviation projection best shows

interspaces and carpals on the ulnar (lateral) side of the wrist. (hamate, triquetrum, pisiform, and lunate.

carpal canal projection

shows the hamulus process of the hamate and the pisiform

Forearm consists of

radius and ulna

proximal radioulnar joint

articulation between the proximal radius and ulna. Allows for rotational movement of the wrist and hand

distal radioulnar joint

articulation between the distal radius and ulna. Allows for rotational movement of the wrist and hand

Styloid processes

conical projections on the extreme distal ends of both the radius and ulna. Radial styloid extends more distally than the ulnar styloid process.

Ulnar notch

Small depression on the medial aspect of the distal radius.It's where the head of the ulna fits to form the distal radioulnar joint.

head of ulna

at the distal end of ulna near wrist. Can palpate easily when pronated on little finger side.

Head of radius

at the proximal end of the radius near the elbow joint. Disk-shaped head

body (shaft)

long midportion of both the radius and ulna

Which is shorter? radius or ulna?

Radius

Radius

directly involved in the wrist joint. Rotates around the more stationary ulna.

Neck of radius

tapered constricted area below the head.

radial tuberosity

rough oval process on the medial and anterior side of the radius, distal to the neck.

Ulna

longer of the 2 forearm bones. Mainly involved to form the elbow joint.

Olecranon

proximal beaklike projection from the ulna

coronoid process

distal beaklike projection from the ulna

coronoid tubercle

medial margin of the coronoid process opposite the radial notch.

trochlear notch

large concave depression that articulates with the distal humerus.

radial notch

small, shallow depression located on the lateral aspect of the proximal ulna. Head of radius articulates with ulna here to form the proximal radioulnar joint.

Distal and proximal radioulnar joints

allow rotation of the forearm during pronation. The radius crosses over the ulna near the upper third of the forearm.

humeral condyle

expanded distal end of the humerus. The articular portion of the humeral condyle is divided into 2 parts: the trochlea and the capitulum

trochlea

pulley; spool. Has 2 rimlike outer margins and a smooth depressed center called the trochlear sulcus or groove. Trochlea is more medially located and articulates with the ulna.

capitulum

"little head" - located on lateral aspect and articulates with the head of the radius. "cap" and "head" go together. Earlier, it was called the capitellum. Articular surface that makes up the rounded articular margin is just smaller than that of the trochlea. Significant in lateral positioning.

Epicondyles

projections off the distal humerus

lateral epicondyle

small projection on lateral side of distal humerus above capitulum

medial epicondyle

larger and more prominent than the lateral epicondyle. In a true lateral position, the directly superimposed epicondyles - difficult to recognize. Appear as a proximal to the circular appearance of the trochlear sulcus

coronoid fossa and radial fossa

2 shallow anterior depressions of the humerus. Receive the coronoid process and radial head

olecranon fossa

posterior humerus depression. The olecranon process of the ulna fits into this depression when arm is fully extended. Has fat pads within the deep olecranon fossa - important when diagnosing trauma to the elbow joint.

True lateral elbow

90° flexion. Appearance should have 3 concentric arcs:
1. trochlear sulcus - first and smallest
2. capitulum and trochlea - 2nd - outer ridges/rounded edges
3. trochlear notch of the ulna.

Arcs will appear symmetrically aligned when pure 90°

Synovial joints

all joints of the upper limb are this classification - freely moveable

diathrodial

freely movable

ginglymus

hinge-type of joint - can only flex and extend. Movement only occurs around the transverse axis. - IP, DIP and PIP

ellipsoidal

condyloid - allow movement in 4 directions: flexion, extension, abduction and adduction. And circumduction. - 2nd to fifth MCPs. - most freely moveable. Wrist joint.

circumduction

conelike sequential movement in 4 directions.

1st MCP joint (thumb) movement

ellipsoidal (condyloid) joint but limited due to the less rounded head of the first metacarpal

Sellar

Saddle joint. First CMC joint of the thumb. Allows flexion, extension, abduction, adduction, circumduction, opposition and some degree of rotation.

Plane joint

Gliding joint - 2-5 CMC joints - least amount of movement of the synovial joints. Surfaces are flat or slightly curved with limited movement due to a tight fibrous capsule. Also the intercarpal joints are plane joints.

Intercarpal joints are considered

plane (gliding)

wrist joint is

ellipsoidal (condyloid) - most freely moveable. Only the radius articulates with the wrist - at the scaphoid and lunate carpal bones.

radiocarpal joint

the radius articulates with the wrist - at the scaphoid and lunate carpal bones.

triquetral bone is considered part of

the wrist because it's opposite the articular disk

articular disk

part of the total wrist articulation, including a joint b/w the distal radius and ulna - the distal radioulnar jt

distal radioulnar joint

joint b/w the distal radius and ulna

wrist joint consists of

the articular surface of the distal radius, along with the total articular disk, the scaphoid, lunate and triquetrum

encloses the total wrist joint

articular synovial capsule strengthened by ligaments that allow movement in 4 directions, plus circumduction

Wrist ligaments - 7

Ulnar collateral ligament
Radial collateral ligament

Others seen arthrography or MRI:

Dorsal radiocarpal ligament
Palmar radiocarpal ligament
Triangular fibrocartilage complex (TfCC)
Scapholunate ligament
Lunotriquetral ligament

Ulnar collateral ligament

attached to the styloid process of the ulna and fans out to attach to the triquetrum and pisiform

Radial collateral ligament

Extends from styloid process of radius primarily to lateral side of scaphoid (scaphoid tubercle) but also attaches to the trapezium.

Elbow joint is considered a

ginglymus (hinge) type of joint - flexion and extension. B/w humerus and ulna/radius.

proximal radioulnar joints

trochoidal (pivot) type of joint - part of the elbow joint

ulnar deviation

toward the side of the ulna - opens up and best demonstrates the carpals on the opposite side: scaphoid, trapezium and trapezoid. This projection is often called the "special scaphoid projection"

radial deviation

toward the side of the radius: less frequently used projection. Opens and best demonstrates carpals on the opposite or ulnar side of the wrist: hamate, pisiform, triquetrum and lunate

Generally, do not radiograph the forearms in a xxx position

pronated PA projection. The radius is actually crossing over the ulna in this position.

Radiograph the forearms in a xxx position

AP projection - supinated. Natural anatomical position. Palm up.

Elbow rotation

AP - no rotation. Radius and ulna partially superimposed at proximal joint.

AP - lateral rotation - separation of radius and ulna

AP, medial rotation - superimposed radius and ulna

fat pads

accumulations of fat (aka fat bands, stripes). A displacement of a fat pad may indicate a disease of injury, fracture within a joint, etc.

Most important fat pads

are located around certain joints of the upper and lower limbs

extrasynovial

(outside the synovial sac) but located within the joint capsule. Changes to fat pads can result from fluid accumulation within the joint.

Radiolucent fat pads

seen as densities that are slightly more lucent than surrounding structures. Difficult to visualize. Requires long-scale contrast techniques w/optimum exposure or density.

Wrist joint fat stripes

Scaphoid fat stripe - visualized on PA and oblique view. Elongated and convex, located b/w radial collateral ligament and adjoining muscle tendons immediately lateral to the scpahoid. Abscence or displacement may indicated a fracture on the radial aspect of the wrist.

pronator fat stripe - lateral view of wrist: 1 cm from anterior surface of the radius. May also indicate subtle fractures of the distal radius

Elbow joint fat pads/stripes

Only on lateral view - in AP, they superimpose bony structures.

anterior fat pad - formed by superimposed coronoid and radial pads
posterior fat pad
supinator fat stripe

Anterior fat pad - elbow

formed by superimposed coronoid and radial pads - teardrop shape anterior to the distal humerus. Trauma can distort its shape.

Posterior fat pad - elbow

deep in the olecranon fossa - not visible on exam. If you can see it on a 90° lateral elbow radiograph, the joint has caused its position to change.

To ensure an accurate diagnosis of elbow fat pads

Elbow must be flexed 90° on the lateral view. Visualization of the posterior fat pad is considered more reliable than that of the anterior fat pads.

Supinator fat stripe - elbow

long thing stripe anterior to the proximal radius. May indicated nonobvious radial head or neck fractures

For elbow fat pads to be useful indicators

Elbow must be
1. flexed 90°
2. in a true lateral position
3. optimum exposure techniques for soft detail to vis. fat pads

General positioning

1. Patient seated
2. Move body away from x-ray beam and scatter as much as possible.
3. Table top height s/b near shoulder height so arm can be supported fully
4. Move Bucky try to opposite side of table to reduce scatter produced by the Bucky device.

Gonadal shielding

Use due to divergent x-ray beam and scatter for those seated at the end of the table.Use shielding for all pts.

Distance

SID = 40 tabletop height (not Bucky)

Trauma pts.

Take on the table or on the stretcher.

Pediatrics/Patient motion

May need to use immobilization to help children maintain the proper position. Sponges, tape, sandbags with caution b/c of their weight, Parents with proper shielding. Speak in calm soothing manner

Geriatric patients

Provide clear and complete instructions. May have difficulty holding strenous positions, so using immobilization may be needed.

Some techniques may need to be

reduced, like the case for osteoporosis, osteoarthritis andn osteomyelitis and rheumatoid arthritis

Principal exposure factors

Low to medium kVP - 50-70
Short exposure time
Small focal spot
Adequate mAs for sufficient density.

Film should show soft tissue margins for fat pad visualization and fine trabecular markings of all bones

Cassettes

Use cassettes with detail-intensifying screens

Grids

are NOT used as part is less than 10cm.

Increase exposure with Cast

Small to medium plaster cast - increase mAs 50-60% or +5-7 kV

Large plaster cast - increase mAs 100% or +8-10 kV

Fiberglass cast - increase mAs 25-30% or 3-4 kv

collimation

should be evident on all four sides if IR is large enough

IR

use smallest IR size for the specific part. Two projections can be taken on one IR but it requires close collimation

Lead masks

Placed on top of the IR to help prevent exposure from scatter and secondary radiation from the adjacent exposure

Parallel

always place the long axis of the part being imaged xxx to the long axis of that portion of the IR being exposed.

Orient all body parts

in the same direction when 2 or more projections are taken on same IR

Markers

place ID info and side markers in the corner least likely to superimpose essential anatomy

CR centering for upper limb

1. Part s/b parallel to plane of IR
2. CR s/b 90° or perp. to part and IR unless specific angle
3. CR s/b directed to correct centering point

Digital imaging considerations

1. Collimation s/b closely restricted to the part
2. 30% rule - 30% of the image plate s/b exposed
3. Lead masking - used when taking 2 images on the same IR
4. body part and CR s/b accurately centered
5. Grid s/n/b used as part is less than 10cm, but with digital radiography, this may not be a choice due to the grid's being built into the IR mechanism.
6. Evaluation of exposure index: critique for exposure accuracy. Check for acceptable exposure index of "S" number

Exposure factors

Use ALARA.
High kVP - min of 50-60 kVp
Lowest mAs (insuffient will be grainy)

Arthrography

Used to image tendinous, ligamentous, and capsular pathology associated with diarthrodial joints like wrist, elbow, shoulder and ankle. Uses radiographic contrast medium injected into the joint capsule under sterile conditions

CT and MRI

used on upper limbs to see soft tissue and skeletral involvement of lesions and soft tissue injuries. Excellent for determining displacement and alignment relationships w/certain fractures that may be difficult to visualize w/conventional radiographs

Nuclear medicine

Useful for osteomyelitis, metastatic bone lesions, stress fractures, and cellulitis. 24 hours of onset. More sensitive than radiography - it assesses the physiologic aspect instead of the anatomic aspect.

# of shots required for the wrist

3

Ulnar deviation best shows

the scaphoid opened up. Ulnar deviation is sometimes called the "scaphoid projection"

Radial deviation best shows

the lunate, triquetrum, pisiform and hamate opened up

Which forearm bone is directly involved in the wrist joint

Radius

In which position of the hand does the radius cross over the ulna

pronation

Which bone's styloid process sticks out more distally?

the radius' styloid process

trochlear sulcus (groove)

the smooth depressed center portion of the trochlea. Appears circular on a lateral end-on view. More radiolucent on a radiograph.

The 3 concentric arcs are formed by

1. trochlear sulcus - first and smallest arc
2. Double-line outer ridges or rounded edges of the capitulum (smaller of the 2) and trochlea (the larger)
3. Trochlear notch

Which epicondyle of the distal humerus is larger

the medial epicondyle

What indicates a true lateral elbow position

the directly superimposed epicondyles are seen as proximal to the circular appearance of the trochlear sulcus

the total wrist joint is enclosed by

an articular synovial capsule strengthened by ligaments that allow movement in 4 directions, plus circumduction.

Which elbow rotation separates the ulna and radius

The AP, lateral rotation

which elbow rotation partially superimposes the radius and ulna

The AP, without rotation

Which elbow rotation superimposes the radius and ulna

AP, medial rotation

Bone metastases

transfer of disease/cancerous lesions from one organ to another

bursitis definition

inflammation of the bursae or fluid-filled sacs that enclose joint.

bursitis appearance

fluid-filled jt space with possible calcification

carpal tunnel syndrome def

compression of median nerve as it passes thru the center of the wrist

carpal tunnel appearance

possible calcification in the carpal sulcus

fracture definition

break in the bone

fracture appearance

disruption in bony cortex with soft tissue swelling

joint effusion def

accumulated fluid in jt cavity. sign of an underlying condition

joint effusion appearance

fluid-filled jt cavity

osteoarthritis def

noninflammatory jt disease - degenerative. Gradual deterioraion of articular cartilage with hypertrophic bone formation

osteoarthritis appearance

narrowing of jt space w/periosteal growths on the jt margins

osteomyelitis def

infection of bone or bone marrow

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