MSK clinical Flashcards
What causes Erb’s palsy?
Damage to ROOTS C5 and C6 from excessive increase in the angle between neck and shoulder. This can happen in a difficult birth or due to shoulder trauma
What are the symptoms and signs of Erb’s palsy?
Affects nerves derived from primarily C5 and C6:
1. Waiter’s tip deformity
a)
In Erb’s palsy why the following muscles are paralysed: biceps brachii, brachialis, coracobrachialis, supraspinatous, infraspinatous, subclavius, deltoid and teres minor
C5 and C6 nerve roots make up the following peripheral nerves:
- Musculocutaneous: BBC muscles
- Axillary: deltoid, teres minor (triceps brachii long head - triceps not paralysed due to lateral head innervation by radial nerve)
- Suprascapular nerve: innervates supraspinatous and infraspinatous
- Subclavian nerve: innervates subclavius
The following movements are lost or greatly weakened in Erb’s palsy– abduction at shoulder, lateral rotation of arm, supination of forearm, and flexion at shoulder. Why is shoulder abduction affected?
Supraspinatous - first 15 degrees of arm
Deltoid - 15-90 degrees
Both muscles are paralysed due to loss of C5,C6 innervation
The following movements are lost or greatly weakened in Erb’s palsy– abduction at shoulder, lateral rotation of arm, supination of forearm, and flexion at shoulder. Why is lateral rotation of the arm affected?
Deltoid (posterior fibres), infraspinatous and teres minor are involved in lateral (external) rotation. These are weakened/paralysed in Erb’s palsy
The following movements are lost or greatly weakened in Erb’s palsy– abduction at shoulder, lateral rotation of arm, supination of forearm, and flexion at shoulder. Why is supination of the forearm affected?
The main supinator of the forearm is biceps brachii which is paralysed by lack of innervation by the musculocutaneous nerve
The following movements are lost or greatly weakened in Erb’s palsy– abduction at shoulder, lateral rotation of arm, supination of forearm, and flexion at shoulder. Why is flexion at the shoulder affected?
(Coracobrachialis), biceps brachii, deltoid (anterior fibres) and pectoralis major contribute to shoulder flexion. In Erb’s palsy coracobrachilais, biceps, deltoid are all paralysed leaving pec major unable to complete the action fully on its own
Why is there a loss of sensation down the lateral side of the arm in Erb’s palsy?
Due to the loss of sensory innervation by the cutanous branches of the axillary and musculocutaneous nerves
Describe the actions affected that give the ‘waiter’s tip’ deformity that is seen in Erb’s palsy
The arm hangs limply. There is unopposed medial rotation by Pec major (the external rotators of the deltoid and infraspinatous are paralysed) and the forearm is pronated due to loss of the main supinator, biceps brachii
Klumpke’s palsy is a lower brachial plexus injury. It is less common than the upper brachial plexus injury, Erb’s palsy. What causes it?
Excessive abduction of the arm e.g. catching hold of a branch of a tree when falling
What nerve root and therefore peripheral nerves are affected by Klumpke’s palsy?
It affects T1 nerve root and therefore mainly the ulnar and median nerves
Why in Klumpke’s palsy are the small intrinsic muscles of the hand affected by not the flexors of the forearm?
The T1 nerve root is affected, therefore affecting mainly the ulnar and median nerves. These nerves together supply all the flexor muscles of the forearm and the intrinsic muscle of the hand. However the flexor muscle of the forearm are innervated by different roots of the median and ulnar nerves and are therefore unaffected
Where is sensory loss felt in Klumpke’s palsy?
Along the medial side of the arm - T1 dermatome
What would you observe if a patient had damage to their long thoracic nerve and pushed their arms against a wall?
Winging of the scapula due to paralysis of the serratus anterior muscles - these muscles no longer hold the scapula against the ribcage whilst their upper limbs reach anteriorly
How can the long thoracic nerve become damaged?
Axillary node clearance for breast cancer
What is a common cause of damage to the axillary nerve?
Fractures of the upper humerus where the axillary nerve wraps around
What movements of the arm would be impaired with axillary nerve damage?
Abduction of the arm - beyond 15 degrees
The median nerve is not commonly damaged at the brachial plexus. Where is it vulnerable to damage?
Elbow - supracondylar fractures of the elbow
Wrist - lacerations, carpal tunnel syndrome
If the median nerve is damaged at the elbow causing LONG-STANDING DAMAGE what would you observe?
Hand of benediction - when asking a patient to form a fist they would be able to flex their 4th and 5th digit but not their 1st, 2nd or 3rd - due to the paralysis of their lateral two lumbricals, long flexors of the forearm and the lateral half of FDP. The 4th and 5th digit are unaffected because they are innervated by the ulnar nerve
What signs of short-term damage to the median nerve may you observe?
Almost unopposed extension and supination
Hand signs may occur (including loss of thumb flexion)
Why might a superficial laceration at the wrist cause loss of sensation of the lateral palmar surface of the hand and first digit but not a loss of sensation on palmar surface of the 2nd,3rd and half of the 4th digit and dorsal surface of the tips of the 1st, 2nd and 3rd digits?
In the wrist the median nerve throws off a branch called the palmar cutaneous branch before it enters the flexor retinaculum. Superficial cuts at the wrist can damage this cutaneous nerve but not affect the median nerve below which is protected by the thick connective tissue of the retinaculum. The median nerve then throws off digital cutaneous branches which supply the dorsal tips of the lateral three digits and the palmar surface of the 2nd, 3rd and half of the 4th digit
What is a common cause of radial nerve damage?
Injuries can occur in the axilla, commonly form shoulder dislocation - which pulls on the radial nerve due to its close connection with the humerus in the radial groove
What would be the signs of radial damage at the brachial plexus in a patient?
Paralysis of the triceps (lateral and medius heads) and the extensors of the forearm, leading to wrist drop (unopposed flexion).
Loss of sensation of the posterior and lateral upper arm and posterior forearm
What shoulder position causes the least protection to the contents of the axilla - puts them most at risk of damage?
Abduction of the shoulder
Why are the axillary nodes cleared in some cases of breast cancer?
75% of lymph from the breast drains into the axillary lymph nodes (along with lymph from the upper arm). If breast cancer is found these nodes are sampled to look for spread. If any contamination these nodes need to be surgically cleared
In knee injuries which ligaments are commonly damaged?
Collaterals
Cruciates
Menisci
Sometimes all three = ‘unhappy triad’
If you damage the medial collateral ligament what else is likely to be damaged?
Medial meniscus- they are firmly attached to each other
How are you likely to get the ‘unhappy triad’ knee injury?
- Blows to the side of the knee
2. Lateral twisting of the knee
When is the anterior cruciate ligament susceptible to injury?
When the knee is flexed because it is taut.
What is meant by the unhappy triad?
Torn:
- anterior cruciate ligament
- tibial collateral ligament
- medial meniscus
A blow to the inside of the knee opens up which side of the knee?
Lateral side of the knee
What movements does the anterior cruciate ligament limit?
- Femur sliding posteriorly on the tibia
- Hyperextension
- Medial rotation of femur when foot is on ground and leg is flexed
How can you test for anterior cruciate ligament damage?
Anterior draw sign
How can the posterior cruciate ligament be damaged?
Falling onto the tibial tuberosity with a flexed knee
How can you test for posterior cruciate ligament damage?
Posterior draw sign
What movements does the posterior cruciate ligament limit?
- Prevents the femur from sliding anteriorly on the tibia (particularly when the knee is flexed)
What direction do patella dislocations normally occur?
Laterally
What causes patella dislocations?
Direct trauma/ twisting movement
How can patella fractures occur?
- Direct force
- Severe force from extensors
3.
Name three important types of bursitis that can occur in the knee joint
- Supra-patellar
- Pre-patellar - house maid’s knee
- Superficial infra-patellar - clergyman’s or roofer’s knee
What is the worry with suprapatellar bursitis?
Infection can spread to knee joint due to communication.
What causes bursitis?
Chronic friction of direct trauma.
What is a popliteal cyst (Baker’s cyst)? How should it be treated?
It is abnormal fluid filled sacs of synovial membrane in the popliteal fossa and is a sign of chronic knee effusion. There is no point draining it as it connects to the synovium of the knee joint and it may cause infection.
What methods are used to investigate the knee?
- Imaging - plain films/MRI (NOT X-ray as doesn’t show soft tissue, MRI is gold standard
- Arthroscopy -diagnostic and therapeutic
- Aspiration
- Clinical examination
What can herniation of the nucleus pulposus impinge upon?
Spinal nerves
What is syndactyly?
Fusion of digits - may involve just connective tissue or bones may be fused. It is a defect in the sculpting of the digital rays.
What is polydactyly?
A genetic recessive trait which causes the formation of extra digits.
What is amelia?
Complete absence of a limb.
What is meromelia?
Partial absence of one or more limb structures.
What is phocomelia? What can cause it and why?
A rare congenital deformity in which the hands or feet are attached close to the trunk, the limbs being grossly underdeveloped or absent. This occurs as a consequence the teratogen phalidomide which is toxic to the AER and other tissues. It causes loss of AER and therefore loss of further extension of the limb bud.
Why are radiographs of epithyseal growth plates tricky to analyse?
Soft tissue like cartilage is translucent.
What can damage to epithyseal plates in children cause?
Deformities of long bones.
What is avascular necrosis?
Death of bone due to interruption of blood supply.
What can be the causes of avascular necrosis?
It has varied causes: fracture, dislocation, steroid use, radiation, decompression sickness (O2 bubbles in blood cut off blood supply).
What are the consequences of avascular necrosis?
It leads to collapse of the necrotic segment and secondary osteoarthritis.
What are the features of synovial joints?
- Synovial membrane
- Diarthrosis - freely moveable
- Articular cartilage - usually hyaline
- Fibrous capsule
- Bursa
- Tendon sheaths
- Synovial fluid
- Intra-articular menisci/disc
- Fat pads
What does the articular capsule of a synovial joint consist of?
Fibrous capsule and synovial membrane.
What is the role of the articular cartilage of synovial joints?
- Smooth, low friction in movement
2. Resists compression
The articular cartilage in synovial joints is usually hyaline cartilage, in which joints is there are exceptions?
In the following atypical synocial joints, fibrocartilage is used instead: acromioclavicular, sternoclavicular and temporomandibular.
What is occurring when you crack you joints?
Theory:
- Bones are pulled away from each other
- Synovial cavity expands
- Synovial fluid volume stays constant
- Partial vacuum produced
- Gasses dissolved in synovial fluid are pulled out of solution
- Makes a popping sound
What are the effects of ageing on joints?
- Decreased production of synovial fluid
- Thinning of articular cartilage (due to wear)
- Shortening of ligaments and decreased flexibility
- Degenerative changes
What is arthritis?
It is inflammation and stiffness of a joint (not in itself a diagnosis). There are over 100 different forms. Symptoms include: pain, swelling, stiffness. Signs: redness, swelling, deformity, tenderness, reduced range of movement, abnormal gait (if present in lower limbs).
What is the most common form of arthritis?
Osteoarthritis - localised loss of cartilage, remodelling of adjacent bone, eroding mensicus and associated inflammation caused by wear and tear.
On an X-ray what would you may you see in an osteoarthritic joint?
- Osteophytes - protrusions of bone around the joint
- Reduced joint space
- subarticular schlerosis - increased calcification
- Bone cysts - ingress of synovial fluid
What can occur due to fragments of cartilage breaking of an osteoarthritic joint?
Joint locking.
What is rheumatoid arthritis?
An autoimmune disorder in which autoantibodies (rheumatoid factor) attack the synovium causing synovial inflammation. This leads to joint erosion (bone and cartilage loss) and deformity especially notable in the MCP and PIP joints, cervical spine, feet but it can involve larger joint.
What is the aetiology of rheumatoid arthritis?
- Peak age 40-50 (can be juvenile)
- Women more commonly affected (2-3:1)
- 1% of population
What other organs can be damaged by rheumatoid arthritis?
Eyes, skin, lungs, heart and blood vessels, kidneys and blood (erythrocytes -> anaemia).
What are the X-ray features of rheumatoid arthritis?
- Narrowing of joint space
- Ulnar sublaxation and gross deformity
- Juxta-articular bony erosions (in non-cartilage protected bone)
- Perarticular osteopenia - less matrix in bone
Pannus formation occurs in RA. What is it?
In RA, the hypertrophied synovium (also called pannus) invades and erodes contiguous cartilage and bone.
When does subacromail bursitis cause pain? What is this called?
On abduction of the arm between 50-130 degrees. This is called ‘painful arc syndrome’.
What is the function of the subscapular bursa?
It facilitates the movement of the subscapularis tendon over the scapula. It communicates the joint cavity.
What two joints move during shoulder joint movement?
Glenohumeral joint and scapulothoracic joint (2:1)
What is the scapulathoracic joint?
The scapula moves over the thorax as if it was a joint.
What is vulnerable if intramuscular injection into the deltoid muscle is given higher than 4cm from the acromion end?
The axillary nerve
What is vulnerable from shoulder dislocation and fractures of the surgical neck?
Axillary nerve damage.
Which part of the glenohumeral joint is least supported? Therefore which direction is shoulder dislocation most likely to occur?
Inferiorly.
When does shoulder dislocation occur? What type of dislocation is this classifies as? How does the dislocated shoulder appear?
Usually caused by trauma on a fully abducted arm. It is clinically defined as anterior dislocation because the humeral head locates anteriorly, due to the pull of pectoralis major (powerful adductors). Squaring off of the shoulder occurs because the humeral head comes to lie below the coracoid process.
Why may a previous shoulder dislocation cause recurrent dislocation?
The capsule and rotator cuff may tear and lead to instability of the joint.
How do you test for axillary nerve damage in a shoulder dislocation?
- Loss of sensation in the regimental badge area - supplied by a branch of the axillary nerve called the lateral cutaneous nerve of the arm.
- DO NOT test motor function as this could cause more soft tissue damage and injure the axillary nerve.
What causes painful arc syndrome?
The suprspinatous tendon rubbing under the coracoacromial arch causing irritation and inflammation of the supraspinatous tendon and bursa. This can lead to sub acromial bursitis (+/-calcification), supraspinatous tendonitis (+/-calcification) and degeneration and rupture of tendons.
What are predisposing factors for painful arc syndrome?
- Repetitive overuse - sports (rachet, swimming), work involving overhead use of arms
- Age - degenerative changes in tendons
- Avascularity of supraspinatous tendon
- Slight differences in anatomy may make impingement more likely
How would you treat supraspinatous tendinitis?
- Conservative treatment: rest, analgesia and physiotherapy
2. Severe cases - steroid injections and surgery can be considered
What is the cause of lateral epicondylitis or ‘tennis elbow’?
It is caused by repeated use of superificial extensor muscles which strains their common tendinous attachment to the lateral epicondyle. It causes inflammation of the periosteum of the lateral epicondyle.
What age groups is lateral epicondylitis most commonly seen in?
Peak age of onset is 40-50 year olds.
Which artery can be palpated in the cubital fossa to measure a pulse? How can this artery be located?
Brachial artery. It is medial to the biceps tendon and can be located by getting the patient to briefly flex their bicep mucscles.
When measuring blood pressure which artery in the cubital fossa is the stethoscope placed over to listen to the korotkoff sounds?
Brachial artery
Which vein located in the roof of the cubital fossa is commonly used in venepuncture? What veins is it a branch of?
Median cubital vein. It is a branch between the basilic and cephalic veins.
How can a supracondylar fracture of the humerus occur?
Usually by falling on a flexed elbow.
What is a supracondylar fracture of the humerus?
A transverse fracture spanning between the two epicondyles.
What can be the consequences of a supracondylar fracture of the humerus?
The displaced fracture fragments can impinge on the contents of the cubital fossa and cause median or radial nerve damage and Volkmann’s ischaemic contracture.
What is Volkmann’s ischaemic contracture? How is it caused?
Interference to the blood supply of the brachial artery to the forearm (e.g. a supracondylar fracture of the humerus causing direct trauma or post-fracture swelling. The resulting ischaemia causes flexor muscle to become fibrotic and shortened resulting in uncontrolled flexion of the hand.
What is fasiculation? What disease can it be an early sign of?
They are small, local, involuntary muscle contraction and relaxation, which may be visible under the skin. Most the time this is normal but it can be a sign of early motor neurone disease.
When are the contents of the axilla at most risk of injury?
When the arm is fully abducted because the axillary region is at its smallest.
What is thoracic outlet syndrome?
Compression of vessels and nerves between the superior border of the scapula, lateral border of the first rib and posterior surface of the clavicle (axillary inlet).
What can cause thoracic outlet syndrome?
Common causes are trauma (e.g. fracture of the clavicle) and repetitive use (commonly seen in profession where lift arms frequently).
What are the symptoms of thoracic outlet syndrome?
Pain in the affected limb (where depends on nerve damage), tingling, muscle weakness and discolouration.
Why are axillary lymph nodes biposied?
~75% of breast lymph drains into axillary nodes therefore they are biopsied if breast cancer is suspected.
If breast cancer is found what operation of the axillary lymph nodes may be carried out? Why? What can be the complications of this operation?
Axillary clearance. To prevent the cancer spreading. The long thoracic nerve may be damaged as it lies near the lymph nodes.
How can damage to the long thoracic nerve be assessed?
Get patient to push hands against a wall and look for winging of the scapula - the medial angle of the scapula moving away from the thoracic rib cage due to serratus anterior weakness.
What causes the symptoms of carpal tunnel syndrome?
Compression of the median nerve within the carpal tunnel.
What is the aetiology of carpal tunnel syndrome?
Can be caused by thickening of the tendons and synovial sheaths that pass through the carpal tunnel, however in the majority of cases the cause is unknown.
