Nerve Palsies in the Limbs Flashcards

1
Q

Every peripheral nerve starts from the __________ - eg. the sciatic nerve is often over 1 metre long from origin to terminal branches

A

spinal cord

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2
Q

what is a dermatome?

A
  • sensory area of skin supplied by a single spinal nerve
  • adjacent dermatomes overlap considerably
  • embryological development of limb buds growing out from body wall results in axial lines (anterior and posterior) - there is no overlap between adjacent pre- and post-axial dermatomes
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3
Q

what are the dermatomes like in the lower limbs?

A
  • lower limb dermatomes distorted by rotation and extension, and “borrowing” of skin from trunk
  • STAND on S1
  • SLEEP on S2
  • SIT on S3

**** on S4 !

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4
Q

what is hiltons law?

A

“The nerves crossing a joint supply the muscles acting on it and the joint itself.”

n.b. may supply 2 joints, eg. hip and knee supplied by femoral, sciatic and obturator nerves –

HIP DISEASE MAY GIVE RISE TO KNEE PAIN

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5
Q

what is a myotome?

A

•group of muscles supplied by one segment of spinal cord

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6
Q

what is the brachial plexus?

A
  • large network of nerves supplying the upper limb, extending from the cervical spine to the axilla
  • anatomical variations common -eg. C4-8 = pre-fixed plexus, C6-T2 = post-fixed plexus
  • Roots
  • Trunks
  • Divisions
  • Cords
  • Branches
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7
Q

how are brachial plexus lesions caused by downward traction, what is damaged and what is the effect?

A
  • downward traction (eg. fall on side of neck)
  • C5, 6 damage (deltoid & shoulder muscles, brachialis & biceps)
  • arm “porter’s tip” (Erb-Duchenne paralysis)

Common in childbirth, and accidents - Pulling baby pulls on upper cords, C5 and C6

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8
Q

what is Arm “porters tip” (Erb-Cuchenne paralysis)?

A

Arm adducted as deltoid no longer works, elbow is extended because biceps not working, forearm pronated and wrist flexed

Right shows child developed it in childbirth, tends to rapidly resolve

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9
Q

what is erbs point?

A

“Erb’s point” is also a term used in head and neck surgery to describe the point on the posterior border of the sternocleidomastoid muscle where the four superficial branches of the cervical plexus—the greater auricular, lesser occipital, transverse cervical, and supraclavicular nerves—emerge from behind the muscle

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10
Q

how are brachial plexus lesions caused by upward traction, what is damaged and what is the effect?

A
  • upward traction (eg. breech delivery)
  • T1 damage (intrinsic muscles)
  • hand “clawed” (Klumpke’s paralysis) – claw hand

Lower cords

This is upward traction instead of downward traction

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11
Q

In descriptive anatomy of forearm, wrist and hand, what words should be used?

A
  • use “RADIAL” and “ULNAR” (rather than lateral and medial)
  • use “VOLAR” or “PALMAR” and “DORSAL” (rather than anterior and posterior)
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12
Q

is the Axillary Nerve at risk and what may it be a complication of?

A
  • at risk - wraps around surgical neck of humerus
  • complication of - # humeral neck, shoulder dislocation, Saturday night palsy (pressure on post. cord of brachial plexus)
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13
Q

what make sup the axillary nerve and what does it supply?

A

C5, C6 - posterior cord

Supplies deltoid and teres minor

Supplies skin over lateral arm – regimental badge area

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14
Q

what motor and sensory loos would be seen in axillary nerve damage?

A
  • motor deficit - loss of shoulder abduction (deltoid)
  • sensory deficit - badge area

If they have reduced sensation then pretty sure axillary nerve has been injured and leads to deltoid atrophy, if identify at point of injury you can introduce physiotherapy to ensure

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15
Q

what are the roots of the radial nerve and where is it located?

A
  • roots - C5, 6, 7, 8, T1, posterior cord
  • in arm, closely associated with - profunda brachii artery
  • enters forearm by passing between - brachioradialis & brachialis (and posterior interosseous branch of radial nerve passes between 2 planes of supinator)

Runs in radial groove of the humerus as it passes from medial to lateral

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16
Q

where is the radial nerve at risk?

A

at risk - spiral groove of humerus & lat. intermuscular septum (and posterior inter-osseous branch at radial neck)

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17
Q

raidal nevre damage may happen in what complication?

A

humeral shaft, Saturday night palsy (pressure on post. cord of brachial plexus), exposure of proximal radius

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18
Q

if the radial nerve is dmaaged, what motor or sensory deficit may be seen?

A
  • motor deficit - wrist drop (extensors)
  • sensory deficit - 1st web space dorsall

Radial nerve palsy symptoms depend on site of lesion:

Axilla = loss of elbow extension, wrist extension and sensory changes forearm and hand

Arm = loss of wrist extension and sensory loss

Forearm = loss of fingers extension (PIN)

Wrist = loss of sensation (SRN) e.g. handcuff

19
Q

what makes up the median nerve?

A

roots - C7, 8, T1

Medial and lateral cord supply

20
Q

where is the median nerve located?

A
  • in arm, closely associated with - brachial artery
  • enters forearm by passing between - two heads of pronator teres
21
Q

what does the median nevre supply?

A

Supplies flexors forearm (apart from FCU an medial half of FDP), LOAF muscles

Supplies sensation to the radial 3.5 digits

22
Q

where is the median nerve at risk and of what complication?

A
  • at risk - volar aspect wrist (& cubital fossa)
  • complication of - carpal tunnel syndrome, wrist lacerations (& supracondylar #’s, Struther’s ligament)
23
Q

if the median nerve is damaged what is the motor and sensory loss?

A
  • motor deficit - thenar wasting (monkey hand), pointing finger
  • sensory deficit - volar aspect thumb
24
Q

what makes up carpel tunnel?

A

Floor – carpal bones

Roof – flexor retinaculum

Contents – FDS x4, FDP x4, FPL and median nerve i.e. 9 tendons and a nerve

25
Q

what are the causes of carpel tunnel?

A

Developmental

Trauma – distal radius fracture

Swellings – ganglion, fibroma, lipoma

Inflammatory – rheymatoid, gout, TB, amyloid

Metabolic – pregnancy, mucopolysaccharidoses, hypothyroidism

26
Q

what are the symptoms of carpel tunnel?

A

Nocturnal pain and paraesthesia in part or all of the median nerve distribution

Wasting of the thenar muscles

27
Q

how do you investigater carpel tunnel?

A

Look – thenar wasting, previous scars, deformity (previous fracture)

Feel – sensation

Move – APB power

Special tests – tinnels, phalens

28
Q

what is shown here?

A

Carpel tunnel release – relieving pressure on the nerve, taken away roof of the carpel tunnel,symptoms should disappear

Can use night splints

29
Q

what make sup the ulnar nerve?

A

roots - C7, 8, T1

Medial cord

30
Q

where is the ulnar nerve found and what is its function?

A
  • in arm, closely associated with - superior ulnar collateral artery (and ulnar artery and nerve very closely interwoven at wrist)
  • enters forearm by passing between - two heads of flexor carpi ulnaris

No braches in arm

Enters forearm between heads of the FCU

Supplies medial half of FDP, FCU and all intrinsic muscles in hand bar LOAF

Sensation to ulnar 1.5 digits – pinky fingers and half ring fingers

31
Q

how is the ulnar nerve at riska dn of what complications?

A
  • at risk – behind medial epicondyle of humerus (& wrist, canal of Guyon)
  • complication of - # humeral condyles (& wrist lacerations)
32
Q

how do you test ulnar nerve power?

A

Test for ulnar nerve power – froments test – key muscles are adductor pollicis (ulnar nerve) and flexor pollicis longus (median nerve) and if ulnar nerve not working patient will cheat and use FPL instead of adductor pollicis

33
Q

if the ulnar nerve if damaged what mtor and sensory loss would be seen?

A
  • motor deficit - claw hand, hypothenar & 1st dorsal interosseous wasting
  • sensory deficit - little finger
34
Q

wher eis the lumbar plexus?

A
  • lies on surface of quadratus lumborum and within body of psoas muscle
  • most major nerves about the hip exit the pelvis by the sciatic foramen, except genitofemoral & ilioinguinal, femoral, lateral femoral cutaneous and obturator nerves
35
Q

what makes up the femoral nerve and where is it?

A
  • roots: L2-4
  • largest branch of lumbar plexus
  • passes through psoas muscle; exits pelvis under inguinal ligament, lateral to femoral artery, vein and lymphatic channels in femoral triangle - VAN with Vein next to “V” of legs
36
Q

what is the role of the femoral nerve?

A
  • supplies quadriceps muscles in thigh (anterior)
  • terminates in long fine sensory branch (Saphenous Nerve - accompanies femoral artery in subsartorial canal of thigh, and long saphenous vein in lower leg and in front of medial malleolus at ankle to supply great toe)
37
Q

what makes up the Lateral Femoral Cutaneous Nerve and where is it found?

A
  • roots: L2,3
  • lies on surface of iliacus muscle; usually exits pelvis under lateral end of inguinal ligament, but variable
38
Q

what is the role of the Lateral Femoral Cutaneous Nerve and what happens if it gets damaged?

A

purely sensory to lateral aspect thigh

compression causes “meralgia paraesthetica”

39
Q

what are the roots of the sciatic nerve?

A

roots: L4-S3

40
Q

wher eis the sciatic nerve found?

A
  • largest nerve in body; main branch of sacral plexus; broad and flat with accompanying artery
  • exits pelvis through sciatic foramen below piriformis muscle
  • runs deep to gluteus maximus muscle
41
Q

what does the sciatic nerve supply?

A

•supplies hamstring muscles in thigh (posterior) and part of adductor magnus, and all lower leg and foot muscles via terminal branches (tibial and common fibular nerves) - height of division variable (really 2 nerves)

42
Q

what is the sciatic nevre at risk from?

A

at risk from posterior dislocation of hip, intra-muscular injections and during surgery (division devastating)

(Red area can hit sciatic nerve and is not safe)

43
Q

what makes up the common fibular nerve?

A
  • roots: L4-S2
  • previously called lateral popliteal nerve, then common peroneal nerve
  • smaller and lateral branch of sciatic nerve
44
Q

where is the common fibular nerve located?

A
  • passes around lateral aspect of neck of fibula (at risk! - deficit causes foot drop and slapping gait - most commonly injured nerve in lower limb)
  • communicating branch to sural nerve
  • divides into superficial and deep fibular nerves