lower limb nerves

Question 1

what are motor nerves?

Answer 1

• carry messages to the muscles

Question 2

what do sensory nerves do?

Answer 2

• supply sense receptors, action potential back up to spine to pass to brain

Question 3

what happens when nerves are leaving vertical column at levels of lumbar vertebrae?

Answer 3

• sacrum converges together to remix the fibres to constitute peripheral nerves

Question 5

what is a plexus?

Answer 5

• branching network of nerves

Question 6

what three nerves form the lumbar plexus?

Answer 6

• femoral, obturator and lateral cutaneous

Question 7

what fibres make up the femoral nerve?

Answer 7

• made up of fibres from L2,L3 an L4

Question 8

where does femoral nerve travel?

Answer 8

• travels on anterior side of the pelvis and thigh

Question 9

what muscles does the femoral nerve innervate?

Answer 9

• rectus femoris, sartorius, vastus lateralis

Question 10

what branches off the femoral nerve? what is its role?

Answer 10

• saphenous nerve, which supplies skin near the ankle

Question 11

what fibres make up the obturator nerve?

Answer 11

• fibres from L2,L3 and L4

Question 12

where does obturator nerve travel?

Answer 12

• between ischium and pubis gap; through obturator canal
• down medial side of thigh

Question 13

what is the lateral cutaneous nerve made up of? what nerves does it contain?

Answer 13

• fibres from L2 and L3
• only consists of sensory nerves

Question 14

where does lateral cutaneous nerve travel?

Answer 14

• goes underneath inguinal ligament before it crosses over hip joint
• goes down onto lateral side of thigh

Question 15

what three nerves make up the lumbosacral plexus?

Answer 15

• superior gluteal, inferior gluteal and sciatic

Question 16

what makes up superior gluteal nerve?

Answer 16

• arises from L5, S1 and S2

Question 17

where does superior gluteal nerve arise from?

Answer 17

• anteriorly out of the sacrum

Question 18

what muscles does the superior gluteal nerve supply?

Answer 18

• medial side of hip e.g. gluteus medius, minimus and tensor fasica

Question 19

what fibres make up inferior gluteal nerve?

Answer 19

• L5, S1 and S2

Question 20

what muscles does the inferior gluteal nerve supply?

Answer 20

• posterior muscles; small branches supply gluteus maximus at back

Question 21

what fibres make up the sciatic nerve? what two types of nerves does it contain?

Answer 21

• arises from L4,L5,S1,S2 and S3
• formed of both anterior and posterior nerves

Question 22

where does sciatic nerve travel?

Answer 22

• sits anteriorly on sacrum then leaves the pelvis via greater sciatic foramen
• passes down back of thigh

Question 23

what does the sciatic nerve pass very close to?

Answer 23

• piriformis muscle

Question 24

what does sciatic nerve split into 2/3 of way down?

Answer 24

• tibial nerve
• common peroneal nerve

Question 25

what is tibial nerve made up from?

Answer 25

- anterior branches of lumbosacral plexus

Question 26

where does tibial nerve travel? where does it enter foot?

Answer 26

- posteriorly across the knee - enters foot medially

Question 27

how does tibial nerve wrap round ankle and what does it give rise to?

Answer 27

- wraps round the back and into foot where it gives rise to medial and lateral nerve

Question 28

what muscles does the tibial nerve supple?

Answer 28

- gastrocnemius, soleus, popliteus, tibialis posterior

Question 29

what is common peroneal nerve made from?

Answer 29

- posterior branches of lumbosacral plexus

Question 30

where does common peroneal nerve travel?

Answer 30

- laterally past the knee

Question 31

what does common peroneal nerve branch into?

Answer 31

- deep= travels anteriorly - superficial = travels laterally

Question 32

what is the deep common peroneal nerve?

Answer 32

- anterior compartment so supplies toe extensors and tibialis anterior

Question 33

what is superficial common peroneal nerve?

Answer 33

- stays lateral so supplies peroneal muscles

Question 34

what muscles does common peroneal supply?

Answer 34

- peroneus longus, fibularis brevis, tibialis anterior

Question 35

what happens if a nerve is damaged?

Answer 35

- loss of sensation in defined area

Question 36

what if nerve is damaged from nerve roots?

Answer 36

- mixed pattern of sensory loss

Question 37

what would a damaged peroneal nerve result in?

Answer 37

- loss of sensation down the outside of leg, onto foot and in between toes

Question 38

what would a damaged femoral nerve result in?

Answer 38

- loss of sensation on front of the high and medial aspect of leg

Question 39

what is a dermatome?

Answer 39

- area of skin that is innervated predominantly by one nerve root

Question 40

why is a dermatome useful in differentiating where we have sensory loss?

Answer 40

- can determine whether its linked to damage at level of vertebrae or a peripheral nerve type damage