L11 Upper Limb Nerve Injuries Flashcards
How do you approach a neurological problem?
Anatomically localise the lesion - whether UMN/ LMN lesion
Consider pathophysiology
Differential diagnosis
Where do the lower motor neurons arise from?
The anterior horn cell of the spinal cord
What type of nerves are cranial nerves and spinal nerves?
LMN
UMN lesions of the upper limb result in:
aka pyramidal insufficiency
Held in flexed posture if chronic
Increased tone
Pyramidal weakness (muscle weakness) because flexor muscles are stronger than extensors
Brisk reflexes
Decreased control of active movement, slowness
Sensory level
LMN lesions lead to what in the upper limb
Wasting/ fasciculations
Flaccid tone (decreased muscle tone)
Weakness in either a myotomal distribution or a peripheral nerve distribution
Dermatomal/ peripheral nerve distribution of sensory loss
What are the 3 anatomical regions for localising the region?
Roots
Brachial plexus
Peripheral nerve
What is a myotome?
The relationship between a spinal nerve and the muscle via the ventral rami
What is a dermatome?
The relationship between a spinal nerve and the skin via the dorsal rami
A dermatome is an area of the skin supplied by nerve fibres originating from a single dorsal nerve root
Coordination problems would localise towards the?
Cerebellum
What landmark corresponds to the C7 dermatome?
The middle finger
What landmark corresponds to the C6 dermatome?
The index finger & thumb
Which muscle does the C5 root innervate and what is the resulting muscle action?
Deltoid
Shoulder abduction
Which muscle does the C6 root innervate and what is the resulting muscle action?
Biceps, brachialis, brachioradialis
Elbow flexion
Which muscles does the C7 root innervate and what is the resulting muscle action?
Triceps, superficial extensors of the forearm, flexors of the forearm
Elbow extension
Wrist flexion & extension
Which muscles does the C8 root innervate and what is the resulting muscle action?
Forearm extensors, deep forearm flexors
Finger flexion & extension
Which muscles does the T1 root innervate and what is the resulting muscle action?
Intrinsic muscles of the hand
Finger abduction
Which root and nerve is responsible for the biceps reflex?
C5
Musculocutaneous nerve
Which root and nerve are responsible for the supinator jerk?
C6 reflex
Radial nerve
Which root and nerve are responsible for the triceps jerk?
C7 conveyed through the radial nerve
Which root and nerve are responsible for the finger jerk?
C8 conveyed through the median and ulnar nerves
What happens to reflexes in LMN lesions?
They are depressed/ reduced
What are the consequences of nerve root impingement?
Pain
Sensory loss
Weakness
Reflex loss
What can cause a nerve root impingement?
Slipped/ herniated disc
Nucleus pulposus herniating into the spinal canal
Name the types of nerve injury
Avulsion
Rupture
Brachial plexus trauma
Neuropraxia blunt injury
Which type of brachial plexus injury has the worst prognosis?
Root avulsion
Preganglionic - close to the root involves the CNS which does not regenerate
Loss of which nerves results in medial winging of the scapula? (inferior border of the scapula moves medially)
Long thoracic nerve (serratus anterior)
Dorsal scapular nerve (rhomboids)
What is a flail arm?
Results from cervical root avulsion - loss of the primary nerve therefore resulting in lack of mobility and sensory loss
What is the cause of ERB’s palsy?
Avulsion of C5/ C6 roots
What are the muscles affected by Erb’s palsy?
Biceps - flexes arm
Brachioradialis - flexed arm in semi prone position
Deltoid - abducts arm
Supraspinatus - abducts arm
Supinator - externally/laterally rotates arm
Name three compression sites causing thoracic outlet syndrome
Between anterior and middle scalene muscles
Beneath the clavicle in the costoclavicular space
Beneath the tendon of pec minor
Name two causes of brachial plexopathy related to cancer
Metastatic brachial plexopathy - infiltration of lower brachial plexus from pan coast tumour
Post radiation brachial plexopathy
Pain is a characteristic feature which of the following types of brachial plexus injuries:
Metastatic brachial plexopathy - infiltration of lower brachial plexus from pan coast tumour
Post radiation plexopathy
OR Brachial neuritis - Parsonage-Turner Syndrome
Metastatic brachial plexopathy - infiltration of lower brachial plexus from pan coast tumour
Brachial neuritis - Parsonage Turner Syndrome
What does damage to the long thoracic nerve cause?
Winged scapula
What muscle does the long thoracic nerve innervate?
Serratus anterior
Name two common sites of compression of the median nerve
Wrist - carpal tunnel syndrome
Elbow
Name the muscles of the hand innervated by the median nerve
Lateral 2 lumbricals
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis
Where does the superficial sensory branch of the ulnar nerve branch off?
In the distal forearm
Which structure does the ulnar nerve go around?
Medial epicondyle
What is Froment’s sign and what is it indicative of?
When a pt is asked to take a piece of paper from the examiner in their thumb and forefinger, the thumb flexes - this is froment’s sign
It is indicative of ulnar palsy - weakness in adductor pollicis
Damage to which nerve causes ‘Saturday night palsy’?
Radial nerve
