Imaging of the upper limb Flashcards
Characteristics of x-rays
Ionising radiation
High voltage used to accelerate electrons produced by cathode in X-ray tubes, where electrons interact with eachother to produce x-rays
What is ionising radiation?
Enough energy to displace orbiting electrons from an atom in the absorbing medium, producing positive ions
What colour is photographic film until exposed to x-rays?
White
ALARA principle
Keeping radiation as low as possible
Why does bone appear white on an x-ray?
Blocks most of the beam
Why does soft tissue appear grey on an x-ray?
Partially blocks beam
Why does fat appear dark grey on an x-ray?
Less dense
Why do air containing tissues appear black on an x-ray?
Block very little of the beam
Characteristics of CT scan
Produced by x-rays
Emitter and detector of x-rays move around patent but are always opposite each other
Images organs/bones/muscle/soft tissue
Can diagnose trauma/cancer/disease
Benefits of CT scans
Non-invasive, accurate, fast, can image multiple tissue simultaneously
Disadvantages of CT scans
Ionising radiation leads to malignancy, anaphylactic reaction with contrast dye
Characteristics of MRI scans
Uses strong magnetic fields and field gradients and radio waves
Utilises how body is mainly H2O
How do MRI scans work?
At the centre of each hydrogen is a proton
Protons act like a magnet - they all line up in the same orientation under the scanner
Radio waves knock protons out of alignment but they realign when scanner switched off
Sends out radio signals that are detected by receivers
Can distinguish between tissues because protons return at different speeds
Computer combines signals to produce image for radiologists
Benefits of MRI scans
Defines soft tissue, bones, joints and cartilage, can detect tumours/blood vessels/organs
Limitations of MRI scans
Time consuming, expensive, claustrophobic, contrast reaction
What is a sagittal plane?
Cuts along midline
What is a transverse plane?
Cuts in half along hips
What is a coronal plane?
Creates forward and backward sides
Characteristics of ultrasound scans
Uses high-frequency sound to define tissues
Transducer sends pulses to tissues and receives echo back which contains spatial and contrast information
Computer created 2D greyscale image
Benefits of ultrasound scans
No radiation, readily available, cheap, portable, can examine physiology/heart/blood vessels/fetus
Limitations of ultrasound scans
Trained operator required, can’t penetrate bone/thermal heating
Characteristics of nuclear medicine
Radioactive tracer injected to diagnose/monitor/treat disease
Commonly use technetium
Uses ionising radiation
Functional not anatomical imaging
What can nuclear medicine scan for?
Fractures/metastases/cancers/brain disorders
Which chemical is used in nuclear medicine?
Technetium
Half life of technetium
6 hours
What is an angiogram?
Invasive radiological procedure where you gain access to the arterial vascular system via an artery puncture using catheters and wires
Which artery enters the top of the upper arm?
Subclavian artery
Where does the right subclavian artery come from?
The brachiocephalic artery
What is the brachiocephalic artery?
First branch of the aortic arch
Where does the left subclavian artery come from?
The third branch of the aortic arch
When does the subclavian artery become the axillary artery?
The lateral border of the first rib
When does the axillary artery become the brachial artery?
Just below the axilla, as it crosses the inferior border of the teres major
When does the brachial artery divide into the radial and ulnar arteries?
Distal to the elbow
Flow chart of blood vessels in arm
Subclavian - axillary - brachial - radial - ulnar
What is a CT angiogram?
Much less invasive
Standard venous cannula and the machinery and radiographers time the scan acquisition according to the vessel they want to study
Which bone does the radial artery follow?
The radius
When it reaches wrist, what does the distal ulnar artery continue as?
Superficial palmar arch
When it reaches wrist, what does the radial artery continue as?
Deep palmar arch
In what direction does blood flow in the hand?
Distal to proximal
Where does the scaphoid receive its blood supply from?
Lateral and distal branches of radial artery
What is the anterior fat pad?
Curvilinear lucency in front of humerus heading towards radial head
What does elevation of the anterior fat pad indicate?
Effusion within the joint because it is normally concealed within the coronoid fossa
Indicates intra-articular fracture
Where is the posterior fat pad?
From humerus to olecranon - it is a Lucent crescent of fat in the olecranon fossa
How many interphalangeal joints are there?
2 - distal and proximal
How many types of phalanges are there?
3 - proximal, middle and distal
Where is the carpometacarpal joint?
Between carpals and metacarpals
What are the 8 carpal bones?
Scaphoid Lunate Triquetrum Hamate Capitate Trapezoid Trapezium Pisiform
What is the physis?
A radiolucent line in a skeletally immature patient which is located between the epiphysis and metaphysis
As the metaphysis and epiphysis mature, it disappears
What happens to the physes as a child grows?
Undergo endochondral ossification
How do the carpal bones ossify?
Starts in capitate and goes round clockwise, ending at pisiform
At birth, no calcification
When does the capitate ossify?
1-3 months
When does the pisiform ossify?
8-12 years
Sequence of ossification of carpal bones
Capitate, hamate, triquetrum, lunate, scaphoid, trapezium, trapezoid, pisiform
Which radioactive isotope is used in nuclear medicine in children?
Technetium 99
What can nuclear medicine show in children?
Bone structures/malignancy/fractures
Characteristics of brachial plexus
Network of nerves supplying skin and upper limb
C5 to T1
At each vertebral level, the paired spinal nerves leave the spinal cord by neural foramen where they divide into anterior and posterior rami
What do the anterior rami do?
Form roots
What do posterior divisions of brachial plexus do?
Innervate skin and muscles of intrinsic back musculature
What are the three trunks of the brachial plexus?
Superior/middle/inferior
Which nerves innervate the superior trunk?
C5 and C6
Which nerves innervate the middle trunk?
C7
Which nerves innervate the inferior trunk?
C8 and T1
How many branches does each trunk split into and where?
2 and posterior triangle of neck
What happens to the two divisions of a trunk of the brachial plexus?
One moves anteriorly and the other posteriorly - they pass into the axilla and recombine into the cords of the B.P
Place roots cords and trunks in order
Roots - trunks - cords
What are the three cords of the BP?
Lateral/posterior/medial cords
What is the lateral cord formed by?
Anterior divisions of superior and middle trunk
What is the posterior cord formed by?
Posterior divisions of superior/middle/inferior trunk
What is the medial cord formed by?
Anterior division of inferior trunk
Which nerves to the three cords give rise to?
Musculocutaneous, axillary, medial, radial and ulna
List the 10 bones/joints of the shoulder
ACJ (acromion process articulates with distal end of clavicle) Subacromion space (below acromion) Glenohumeral joint (humerus and glenoid fossa) Clavicle Acromion process Glenoid fossa Coracoid process Humeral head Greater/lesser tuberosity Scapula
What is the function of the rotator cuff?
Stabilises glenohumeral/shoulder joint
4 muscle in rotator cuff
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
What does the supraspinatus do?
Abduction
What does the infraspinatus do?
External rotation
What does the trees minor do?
External rotation
What does the subscapularis do?
Internal rotation
What ligaments are found in the rotator cuff?
Coracohumeral and glenohumeral
What are the 3 muscles of the anterior arm compartment?
Biceps brachii
Brachialis
Coracobrachialis
What nerve innervates the anterior arm compartment?
Musculocutanous nerve
Which artery supplies the anterior arm compartment?
Brachial
What are the 3 muscles of the posterior arm compartment?
Triceps Brachi
Anconeus
Articularis cubiti
What are the anterior and posterior compartments of the arm divided by?
Fascia
When does compartment syndrome occur?
Increased inter compartmental pressure
When does myonecrois occur?
Interstitial pressure exceeds pressure in capillary bed
Symptoms of compartment syndrome
Pain, paraesthesia, pallor, paralysis, pulseness
9 components of the elbow
Shaft of humerus Olecranon process Trochlea Coronoid process Radial head Ulna shaft Lateral/medial epicondyle Capitulum Trochlear notch
What is the trochlearnotch?
Olecranon and coronoid processes articulate with trochlea
5 components of wrist
Radius Ulna Ulnar/radial styloid Lunate Radiocarpal joint
Where are the flexors in the forearm?
Mainly on palm
Where are the extensors in the forearm?
Backside of arm
What are the three subgroups of the anterior compartment?
Superficial/intermediate/deep
What do muscles in the anterior compartment do?
Flexion at wrist and fingers and pronation
What do muscle din the posterior compartment do?
Extend wrists and fingers
What are muscle in the posterior compartment innervated by?
Radial nerve
What are the superficial and deep layers of the posterior compartment divided by?
Fascia
How many extensors are there?
12
When does compartment syndrome occur?
Increased inter compartmental pressure
When does myonecrois occur?
Interstitial pressure exceeds pressure in capillary bed
Symptoms of compartment syndrome
Pain, paraesthesia, pallor, paralysis, pulseness
9 components of the elbow
Shaft of humerus Olecranon process Trochlea Coronoid process Radial head Ulna shaft Lateral/medial epicondyle Capitulum Trochlear notch
What is the trochlearnotch?
Olecranon and coronoid processes articulate with trochlea
5 components of wrist
Radius Ulna Ulnar/radial styloid Lunate Radiocarpal joint
Where are the flexors in the forearm?
Mainly on palm
Where are the extensors in the forearm?
Backside of arm
What are the three subgroups of the anterior compartment?
Superficial/intermediate/deep
What do muscles in the anterior compartment do?
Flexion at wrist and fingers and pronation
What do muscle din the posterior compartment do?
Extend wrists and fingers
What are muscle in the posterior compartment innervated by?
Radial nerve
What are the superficial and deep layers of the posterior compartment divided by?
Fascia
How many extensors are there?
12
What are the two types of movement occurring at the elbow joint?
Flexion-extension
Pronation-supination
What are the three muscles in the flexion (anterior compartment) muscle group?
Biceps brachii
Brachialis
Coracobrachialis
What does the biceps brachii do?
Attaches scapula to radial tuberosity and fascia of forearm
What does the brachialis do?
Attaches anterior humerus to coronoid process and ulnar tuberosity
What does the coracobrchialis do?
Attaches coracoid process to medial surface of humerus
Which muscle is in the extension-posterior compartment?
Triceps brachii
What does the triceps brachii do?
Attaches scapula and humerus to olecranon and fascia of forearm
What are the three muscles in the anterior compartment of the forearm?
Pronator teres
Flexor carpi radialis
Palmaris longus
What does the pronator teres do?
Attaches humeral head to body of radius
What does the flexor carpi radialis do?
Attaches metacarpals 2 and 3 to humerus medial epicondyle
What does the palmaris longus do?
Attaches medial epicondyle to palmar aponeurosis
Which nerve supplies anterior compartment of arm?
Musulocutaneous nerve
Which nerve supplies posterior compartment of arm?
Radial
Why is the radial nerve liable to injury?
Sits in radial groove - very exposed
Which muscles are paralysed when the humeral shaft is damaged?
Triceps brachii, Brachioradialis, supinator and extensor muscles of wrist
Damage to which nerve causes the characteristic wrist drop?
Radial
