Nerve Palsies in the Limbs Flashcards
Definition of a dermatome
Sensory area of skin supplied by a single spinal nerve
How to remember lower limb dermatomes
STAND on SI
SLEEP on S2
SIT on S3
SHIT on S4
What is Hiltons Law?
The nerves crossing a joint supply the muscles acting on it and the joint itself
Definition of myotome
Group of muscles supplied by one segment of the spinal cord
What is the component of a dorsal route?
Sensory
What is the component of a ventral route?
Motor
C5 myotome pattern
elbow flexors
C6 myotome pattern
wrist extensors
C7 myotome pattern
elbow extensors
C8 myotome pattern
finger extensors
T1 myotome pattern
intrinsic hand muscles
L2 myotome pattern
hip flexors
L3 myotome pattern
Knee extensors
L4 myotome pattern
ankle dorsiflexors
L5 myotome pattern
long toe extensors
S1 myotome pattern
ankle plantar flexors
What is the brachial plexus?
Large network of nerves supplying the upper limb, extending from the cervical spine to the axilla
What is the prefixed plexus of the brachial plexus?
C4-8
What does the brachial plexus consist of? RUSSEL TAILOR DRINKS COLD BEER
Roots Trunks Divisions Cords Branches
What do the cords of the brachial plexus lie in relation to?
The axillary artery
Roots and cord of the axillary nerve
C5, 6
Posterior cord
What does the axillary nerve wrap around?
The surgical neck of the humerus
What does the axillary nerve supply?
Deltoid and teres minor
Skin over lateral arm = regimental badge area
What results from axillary nerve palsy?
Deltoid atrophy
Loss of shoulder abduction (deltoid)
sensory deficit over badge area
When is the axillary nerve at risk?
Fracture of humeral neck
Shoulder dislocation
Saturday night palsy (pressure on posterior end of the brachial plexus)
Roots and cords of the radial nerve
C5,6,7,8, T1
Posterior cord
What does the radial nerve supply?
Triceps
BCR
ECRL
ECRB
What two muscles does the radial nerve pass through to get to the forearm?
Brachioradialis
Brachialis
When is the radial nerve at risk?
Fracture of the humeral shaft
Saturday night palsy
Exposure of the proximal radius
Presentation of radial nerve palsy
Wrist drop (extensors) Sensory deficit in 1st webspace dorsally Loss of elbow and wrist extension Sensory changes in forearm and hand Loss of finger extension (PIN) Loss of sensation at wrist (SRN)
How could radial nerve entrapment occur?
Humerus fracture
Roots and cords of the median nerve
C5,6,7,8, T1
Medial and lateral cords
What does the median nerve supply?
Flexor of forearm - bar FCU - medial half of FDP LOAF muscles - L = lateral 2 lumbricals - O = opperves pollicus - A = adbuctor pollicus brevis - F = flexor pollicus brevis Sensation to radial 3.5 digits
When is the median nerve at risk?
carpal tunnel syndrome
wrist lacerations
supracondylar fractures
Presentation of medial nerve palsy
Thenar wasting (monkey hand) Pointing finger Sensory deficit to volar aspect of thumb
Roots and cords of ulnar nerve
Roots C7,8, T1
Medial cord
What does the ulnar nerve supply?
medial half of FDP and FCU
all instrinsic muscles of the hand BAR LOAF
Sensation to ulnar 1.5 digits
When is the ulnar nerve at risk?
Fracture of humeral condyles
wrist lacerations
Presentation of ulnar nerve palsy
claw hand - hyperextension at MCPJ, flexion at IPJs hypothenar and 1st dorsal IO webspace sensory deficit of little finger Guttering Ulnar paradox
Roots and cords of musculotaneous nerve
C5,6,7
Lateral cord
What does the musculotaneous nerve supply?
Elbow joint
Causes of carpal tunnel syndrome
Developmental Idiopathic Trauma (distal radius fracture) Swelling - ganglion, fibroma, lipoma Inflammatory - RA - gout - TB - amyloid metabolic - pregnancy - mucopolysaccharides - hypothyroidism
Symptoms of carpal tunnel syndrome
Nocturnal pain and paraesthesia in part or all the median nerve distribution
wasting of thenar muscles (once wasted, unlikely to return)
numbness on ulnar side of hand and difficulty doing fine tasks
Investigations for carpal tunnel syndrome
Look for - thenar wasting - previous scars - deformity (previous fracture) Feel = sensation more - APB power Special tests - Tinnels and phannels Froment's test
Roots of the sciatic nerve
L4, 5, S1, 2, 3
What does the sciatic nerve supply?
Posterior thigh muscles
Leg muscles
Foot muscles
What does the inferior gluteal nerve supply?
Gleuteus maximus
Roots of the lumbar plexus
L1-5
Main branches of lumbar plexus
Femoral nerve
LFCN
Obturator
What is the hip innervated by?
Predominately OBTURATOR NERVE
Femoral nerve
Lateral femoral cutaneous nerve
Roots of the femoral nerve
L2-4
What does the femoral nerve supply?
(anterior) quadriceps muscles in thigh
hip joint
Roots of the lateral femoral cutaneous nerve
L2,3
What does the lateral femoral cutaneous nerve supply?
Purely sensory to the lateral aspect of the thigh
What does compression of the lateral femoral cutaneous nerve cause?
Meralgia paraesthesia
What is largest nerve in the body?
The Sciatic nerve
What does the sciatic nerve supply?
Hamstring muscles (posterior)
Part of the adductor magnus
All lower leg and foot muscles
When is the sciatic nerve at risk?
Posterior dislocation of the hip
Intra-muscular infections
during surgery
Roots of the common fibular nerve
L4-S2
Presentation of common fibular nerve deficit
foot drop
slapping gait
What does palsy of the common peroneal nerve cause?
Foot drop
What is Erbs palsy?
Deficit of the upper brachial plexus (C5,6), traction of C5 + C6 (+/- 7)
Presentation of erbs palsy
Waiters tip position
- shoulder is adducted and internally rotated
- elbow is extended
- wrist is flexed
What is Klumpe’s palsy?
Deficit of the lower brachial plexus (C8, T1), traction of C8/T1
Presentation of klumpe’s palsy
claw hand
hyperextended wrist
What syndrome is the median nerve affected?
Carpal tunnel syndrome
What syndrome is the ulnar nerve affected?
cubital tunnel syndrome
If someone develops winging of the scapula, what nerve is affected?
Long thoracic nerve
When can the long thoracic nerve be damaged?
Masectomy
How can nerve root pain be distinguished from other types of pain?
Pain by dermatomal distribution with associated neurological deficit
