Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Semester 2 Musculoskeletal System > L12: Nerve injuries in the lower limb > Flashcards

L12: Nerve injuries in the lower limb Flashcards

1
Q

Describe the basic structure of a neurone?

A 
Dendrites--> thin structures arising from the cell body 
Cell body--> Collates information 
Axon hillock--> origin of axon
Axon--> specialised cellular extension
Synaptic knob--> synapses
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe the basic structure of a nerve?

A

Bundle of axons and supporting cells
Axon surrounded by endoneurium (glucocalyx and mesh of collagen)
Bundle of axons–> fascicles
Fascicle surrounded by perineurium
Fascicles grouped and surrounded by epineurium
Own blood supply–> vasa nervorum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the endoneurium?

A

Glycocalyx and mesh of collagen
Surrounded by endoneurial fluid
Similar to blood brain barrier and CSF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the Seddon classification?

A

Way of classifying nerve injuries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the different classes in the Seddon classification?

A

Class I: Neurapraxia
Class II: Axonotmesis
Class III: Neurotmesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is Neurapraxia?

A 
Mildest type 
Temporary physiological block of conduction of the affected neuron- No conduction across damaged area- Proximal and distal normal
Endo-, Peri- and epineurium all in tact 
No Wallerian degeneration 
Sensory and motor loss distal to injury 
Full recovery--> Period of days to weeks
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is Axonotmesis?

A

Loss of continuity of axon and myelin sheath
Endo-, Peri and epineurium are preserved
Wallerian degeneration–> 24-36 hours –> distally
Axonal regeneration–> full recovery without surgery
Axon regeneration proceeds at 1-3mm/day–> time of recovery depends on distance from site of injury

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is Neurotmesis?

A

Partial or complete division of axons, endo-, peri- and epineurium
Wallerian degeneration –> sensory, motor and autonomic defects severe
Surgical intervention always required
Deposition of scar tissue prevents regeneration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is Wallerian degeneration?

A

Axon distal to injury degenerates–> antegrade or orthograde degeneration (away from cells body)
Starts within 24-36 hours
Prior to degeneration–> distal axon stump is electrically excitable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the process of Wallerian degeneration?

A
  1. After injury–> axon skeleton disintegrates, and axonal membrane breaks apart
  2. Followed by degeneration of myelin sheath and infiltration by macrophages
  3. Macrophages and Schwann cells phagocytose debris–> 10-14 days
  4. Within 3 days Schwann cells begin regeneration–> 3 weeks formed ‘Bands of Bunger’–> guide axon regeneration –> denervated muscle atrophys
  5. Axon regeneration successful–> muscle innervated-> muscle regeneration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens if regeneration is unsuccessful?

A

If ends not surgically reopposed, ineffective, unregulated regeneration of axons occurs
Sprouting of axon–> traumatic neuroma forms
Painful
Reinnervation does not occur–> muscle replaced by fibrous tissue and fat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are some of the other causes of neuropathy?

A

Traction (stretch)
Extrinsic pressure–> tumour, abscess, displaced fracture
Medical conditions–> diabetes, alcohol excess and drugs
Tumours of nerves–> Neurofibromas, acoustic neuroma (vestibulocochlear nerve)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a prolapsed intervertebral disc?

A

Commonly called a slipped disc

IVD pushes out of place

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the most common sites for nerve root injuries caused by a prolapsed IVD? Why?

A

L4/5 and L5/S1

Due to mechanical loading at these joints

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

In the lumbar and sacral region of the spine how do the nerve roots exit?

A

Emerge below the respective vertebrae–> L4 exits in L4/5 Intervertebral foramen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the nerve root that exits at the level called? What is the nerve root that exits below called?

A

Exiting nerve root–> exits at same level

Traversing nerve root–> emerges at level below

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

In the lumbar spine which nerve root is normally damaged by a paracentral herniation?

A

Traversing nerve root

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the root value of the sciatic nerve? Which muscles does it innervate?

A

L4, L5, S1, S2, S3
Hamsting muscles–> Biceps femoris, Semimembranosus, Semitendinosus
Adductor magnus (hamstring portion)
Still single sciatic nerve but common peroneal component innervates the short head of biceps femoris, other hamstring innervated by tibial
portion
Branches at popliteal fossa–> Tibial (posterior compartment) and Common peroneal (superficial- lateral, deep- anterior)
Also innervates muscles of the leg and foot

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the cutaneous supply of the sciatic nerve?

A

Innervates skin of
Common peroneal - proximal lateral leg (anterior)
-Superficial peroneal (fibular) nerve- Distal lateral leg and dorsum of foot
- Deep peroneal (fibular) nerve- Between great toe and next toe!

Tibial nerve - Heel of foot (posterior)
–> Medial plantar–> medial sole of foot up to medial 3.5 toes
–> Lateral plantar–> Lateral sole of foot and lateral 1.5 toes
Sural nerve- posterior distal lateral leg (ankle) and lateral side of foot and little toe
(posterior)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the normal course of the sciatic nerve from the pelvis to the leg?

A
  1. Exits via the greater sciatic foramen (going posteriorly)
  2. Anterior and inferior to piriformis
  3. Posterior surface of short external rotators (superior gemellus, obturator internus, inferior gemellus and quadratus femoris)
  4. Enters posterior thigh–> deep to long had of biceps femoris (between biceps femoris and adductor magnus)
  5. Bifucates into tibial and common peroneal at apex of popliteal fossa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are some of the different anatomical variants of the sciatic nerve?

A

Entry into the gluteal region:

  • 90% inferior to piriformis (normal)
  • Sciatic nerve split–> piriformis split–> one exits between muscles and one below
  • Sciatic nerve split–> piriformis normal–> one exits above one below
  • Piriformis split–> exits between muscle
22
Q

What is piriformis syndrome?

A

Sciatic nerve symtoms NOT due to compression of nerve roots BUT compression of sciatic nerve by piriformis muscle

23
Q

What are the symptoms of piriformis syndrome?

A 
Dull ache in buttock 
Sciatic pain in thigh, leg, foot
Pain when walking up stairs or inclines 
Increased pain after prolonged sitting 
Reduced range of motion of the hip joint
24
Q

What are the causes of piriformis syndrome?

A

Spasms of piriformis muscle –> overuse
Direct trauma
Anatomical variation between nerve and muscle (least common)

25
Q

How is piriformis syndrome treated?

A

Activity modification
NSAID
Physiotherapy

26
Q

What would happen if the sciatic nerve was completely transected in the buttock?

A

Hip movement normal–> Gluteus maximus (inferior gluteal nerve), flexion unaffected (flexors–> femoral nerve), adduction unaffected (obturator nerve), abduction unaffected (gluteus medius and minimus–> superior gluteal nerve)
Hamstring paralysed
Knee extension unaffected–> Quadriceps femoris–> femoral nerve
Knee flexion absent–> Flexors –> sciatic nerve (except gracilis (obturator nerve) and sartorius (femoral) but not strong enough)
Dorsiflexion and plantar flexion, inversion and eversion–> paralysed
All movements of toes–> paralysed
Paraesthesia in lateral leg and foot (common fibular nerve)
Paraesthesia in posterior leg and plantar surface of foot (tibial nerve)

27
Q

What is the nerve root of the superior gluteal nerve? WHat does it innervate?

A

L4, L5 and S1

Innervates Gluteus medius and minimus and tensor fascia latae

28
Q

What is the anatomical course of the Superior gluteal nerve?

A

Exits through the greater sciatic foramen above piriformis (with artery and vein)

29
Q

What happens during superior gluteal nerve injury?

A

Normally gluteus medius and minimis contract when opposite foot off the ground raising the pelvis on the opposite side–> allowing leg to be brought through without hitting the ground in walking
Injury–> no contraction of gluteus medius and minimis hence the pelivis on the opposite side drops–> Positive Trendelenburg sign–> foot will catch ground when walking –> patient has to use trunk muscles to raise the pelvis –> Trendelenburg gait

30
Q

What is Meralgia paraesthetica?

A

Injury to lateral cutaneous nerve of the thigh (branch of lumbar plexus, dorsal division L2-3)
Compression of the nerve as it pierces the inguinal ligament or fascia latae in the thigh
Patient experiences burning/stinging sensation over the anterolateral aspect of the thigh
Tenderness on palpation
Reduced sensation in distribution of the nerve
Positive Tinel’s sign–> percussing the nerve at the site of entrapment generate tingling or paraesthesia in distribution of nerves

31
Q

What causes Meralgia paraesthetica? What aggrevates it? How is it relieved?

A

Obesity (abdominal fat compression), pregnancy, tight clothing, wearing a tool belt
Aggrevated by standing or walking
Relieved by lying down with hip flexion

32
Q

What is the course of the lateral cutaneous nerve?

A
  1. Emerges from the lateral border of the psoas major on posterior abdominal wall
  2. Travels across iliac fossa on surface of iliacus muscle
  3. Pierce lateral inguinal ligament
  4. Travels in fibrous tunnel medial to ASIS of pelvis and enters the thigh deep to the fascia lata
  5. Divides into anterior and posterior branches
  6. Becomes superficial 10cm below inguinal ligament and supplies the anteriolateral aspect of thigh
33
Q

How is Meralgia paraesthetic diagnosis confirmed? How is it treated?

A

Absence of motor signs
Excluding intra-abdominal causes of nerve irritation such as tumour
Avoid corsets and tight belts
Local nerve block and sometimes surgery to release trapped nerve necessary

34
Q

What is the spinal root of the femoral nerve? What is the course of the femoral nerve?

A

L2, 3 and 4 in lumbar plexus
Enters femoral triangle beneath inguinal ligament
Lateral to Femoral artery (NAVEL)
Divides into multiple branches 4cm below the inguinal ligament

35
Q

What is the motor innervation of the femoral nerve? What is the sensory distribution?

A

Anterior thigh muscles
–> Flex hip (pectineus, iliacus, sartorius)
–> Extend the knee (Quadriceps femorsis)
Sensory–> anteromedial thigh and medial side of leg and foot
–> Via anterior femoral cutaneous nerve or medial and intermediate cutaneous nerves of the thig), and via saphenous nerve respectively

36
Q

What causes injury to the femoral nerve?

A

Fracture of pelvis or hip
Penetrating wounds
Rare–> surgery (hip replacement or abdominopelvic operations)

37
Q

What is the clinical presentation of femoral nerve injury?

A

Depends on site of injury
Weakness and wasting of quadriceps femoris
Hip flexion compromised–> Although Psoas major and minor, adductor brevis, adductor longus, gracilis and tensor fascia latae nerve supply still intact and they flex the hip
Extension of knee and knee jerk reflex lost–> Quads absent
Anaesthesia/ paraesthesia on anteromedial thigh and medial leg–> medial border of foot

38
Q

What is the spinal root of the tibial nerve? What is it a branch of? What is its course?

A

L4-S3
Branch of sciatic nerve
Crosses popliteal fossa
Deep to soleus muscle
Between flexor digitorum longus and flexor hallucis longus muscle
Passes beneath flexor retinaculum at the medial malleous–> medial calcaneal branch to the heel
Divides into medial and lateral plantar nerves to supply the sole of the foot

39
Q

What happens if the tibial nerve is damaged?

A

Supplies muscles to the posterior leg
Paralysis of gastrocnemius and soleus –> no plantarflexion
Active flexion of the toes will be lost
Inversion of midfoot compromised–> Tibialis posterior paralysed
Unopposed pull of dorsiflexors and everts–> foot adopts calcaneovalgus posture (heel down, foot deviated laterally)
Loss of sensation on sole of foot except middle part of medial side of foot (saphenous nerve) and posterior lateral part of heel (sural nerve)

40
Q

What is the spinal root value of the common peroneal nerve? What is it a branch of? What is its anatomical course?

A

L4-S2
Branch of Sciatic nerve
Travels along superolateral border of popliteal fossa on medial border of biceps femoris
Winds around neck of fibula
Pierce the peroneus longus muscle
Gives off cutaneous branch which supplies skin of lateral leg
Divides into superficial and deep peroneal nerve

41
Q

What causes injury to the common peroneal nerve?

A 
Prolonged bed rest
Pressure from tight plaster cast
Poorly places stirrups during surgery
Fracture to neck of fibula
--> injury to common peroneal nerve where it winds around neack of fibula
42
Q

What is the clinical presentation of fibular nerve injury?

A

Foot drop–> paralysis of tibialis anterior and long extensors of toes
Inversion of ankle–> paralysis of peroneus (fibularis) longus and brevis
Loss of sensation on lateral leg and dorsal aspect of their foot

43
Q

What is the root value of the superficial peroneal (fibular) nerve? What is it a branch off? What is is anatomical course?

A

L4-S1
Common peroneal nerve
Lateral compartment innervator
Commences at neck of fibula, descends between peroneus longus and brevis and lateral aspect of extensor digitorum longus –> supplies peroneus longus and brevis
Continues as cutaneous–> anterolateral leg
Reaches distal 1/3 of leg, pierces deep fascia to run subcutaneously and supplies the dorsum of the foot, excluding the first webspace (deep peroneal nerve), medial border (saphenous nerve) and lateral border (sural nerve)

44
Q

What can cause injury to the superficial peroneal nerve? What is the clinical presentation?

A

Fracture to proximal fibula or penetrating injury to lateral leg–> loss of eversion, loss of sensation over distal anterolateral leg and dorsum of foot, excluding first webspace
Ankle arthroscopy or ankle surgery (lateral approach)–> sensory loss to dorsum of foot only

45
Q

What is the root value of the deep peroneal nerve? What is it a branch off? What is its anatomical course?

A

L4, 5
Common peroneal nerve
Anterior compartment innervator
Commences at neck of fibula
Pierce intermuscular septum to enter anterior compartment
Pierces extensor digitorum longus, next to anterior tibial artery, follows artery, between tibialis anterior and EDL in proximal leg and then between TA and EHL in distal leg, at ankle divides into medial and lateral branches

46
Q

What does the deep peroneal nerve supply in the leg?

A 
Tibialis anterior 
Extensor hallucis longus
Extensor digitorum longus 
Peroneus tertius
Small patch of skin over first dorsal webspace
47
Q

What causes deep peroneal nerve injury? What is the clinical presentation?

A

Common site of mononeuropathy (single nerve dysfunction of lower limb) caused by motor neurone disease, diabetes, ischaemia and vasculitis
Total knee replacement can cause injury
Clinical–> Foot drop, inability to extend toes, small patch of numbness in first dorsal webspace

48
Q

What is the root value of the saphenous nerve? What type of nerve is it? (motor/ sensory)

A

L3 and L4
Sensory nerve
Branch of femoral nerve

49
Q

What is the anatomical course of the saphenous nerve?

A

Branches from femoral nerve in femoral triangle
Anterior to femoral artery in the subsartorial canal as far as hiatus in adductor magnus
Continues to descend vertically along medial side of knee behind sartorius
Pierces fascia lata and becomes subcutaneous
Passes along medial side of leg (great (long) saphenous vein), supplying medial leg and medial border of foot as far as 1st metotarsophalangeal joint

50
Q

How is the saphenous nerve damaged?

A

Saphenous vein cut-down–> obtain venous access in emergency
Orthopedic surgery to distal tibial or medial malleolus
Damages when obtaining saphenous vein for bypass surgery
Port placement for knee athroscopy
Past–> damages during stripping of varicose veins–> no commonly done now (thermal or chemically done)

51
Q

What is the sural nerve? What is its anatomical course?

A

Sensory nerve
Communicating branch from tibial nerve and common peroneal nerve that unite in the posterior leg
Posterolateral direction, posterior to lateral malleolus and along the lateral aspect of the foot
Supplies skin of lateral ankle and foot

52
Q

How is the sural nerve damaged?

A

Harvested for nerve grafting and reconstructive surgery
Relatively minor sensory deficit
Past–> damages during stripping of varicose veins (not commonly done)

Semester 2 Musculoskeletal System (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions