lower limb nerves Flashcards
what are motor nerves?
- carry messages to the muscles
what do sensory nerves do?
- supply sense receptors, action potential back up to spine to pass to brain
what happens when nerves are leaving vertical column at levels of lumbar vertebrae?
- sacrum converges together to remix the fibres to constitute peripheral nerves
what is a plexus?
- branching network of nerves
what three nerves form the lumbar plexus?
- femoral, obturator and lateral cutaneous
what fibres make up the femoral nerve?
- made up of fibres from L2,L3 an L4
where does femoral nerve travel?
- travels on anterior side of the pelvis and thigh
what muscles does the femoral nerve innervate?
- rectus femoris, sartorius, vastus lateralis
what branches off the femoral nerve? what is its role?
- saphenous nerve, which supplies skin near the ankle
what fibres make up the obturator nerve?
- fibres from L2,L3 and L4
where does obturator nerve travel?
- between ischium and pubis gap; through obturator canal
- down medial side of thigh
what is the lateral cutaneous nerve made up of? what nerves does it contain?
- fibres from L2 and L3
- only consists of sensory nerves
where does lateral cutaneous nerve travel?
- goes underneath inguinal ligament before it crosses over hip joint
- goes down onto lateral side of thigh
what three nerves make up the lumbosacral plexus?
- superior gluteal, inferior gluteal and sciatic
what makes up superior gluteal nerve?
- arises from L5, S1 and S2
where does superior gluteal nerve arise from?
- anteriorly out of the sacrum
what muscles does the superior gluteal nerve supply?
- medial side of hip e.g. gluteus medius, minimus and tensor fasica
what fibres make up inferior gluteal nerve?
- L5, S1 and S2
what muscles does the inferior gluteal nerve supply?
- posterior muscles; small branches supply gluteus maximus at back
what fibres make up the sciatic nerve? what two types of nerves does it contain?
- arises from L4,L5,S1,S2 and S3
- formed of both anterior and posterior nerves
where does sciatic nerve travel?
- sits anteriorly on sacrum then leaves the pelvis via greater sciatic foramen
- passes down back of thigh
what does the sciatic nerve pass very close to?
- piriformis muscle
what does sciatic nerve split into 2/3 of way down?
- tibial nerve
- common peroneal nerve
what is tibial nerve made up from?
- anterior branches of lumbosacral plexus
where does tibial nerve travel? where does it enter foot?
- posteriorly across the knee
- enters foot medially
how does tibial nerve wrap round ankle and what does it give rise to?
- wraps round the back and into foot where it gives rise to medial and lateral nerve
what muscles does the tibial nerve supple?
- gastrocnemius, soleus, popliteus, tibialis posterior
what is common peroneal nerve made from?
- posterior branches of lumbosacral plexus
where does common peroneal nerve travel?
- laterally past the knee
what does common peroneal nerve branch into?
- deep= travels anteriorly
- superficial = travels laterally
what is the deep common peroneal nerve?
- anterior compartment so supplies toe extensors and tibialis anterior
what is superficial common peroneal nerve?
- stays lateral so supplies peroneal muscles
what muscles does common peroneal supply?
- peroneus longus, fibularis brevis, tibialis anterior
what happens if a nerve is damaged?
- loss of sensation in defined area
what if nerve is damaged from nerve roots?
- mixed pattern of sensory loss
what would a damaged peroneal nerve result in?
- loss of sensation down the outside of leg, onto foot and in between toes
what would a damaged femoral nerve result in?
- loss of sensation on front of the high and medial aspect of leg
what is a dermatome?
- area of skin that is innervated predominantly by one nerve root
why is a dermatome useful in differentiating where we have sensory loss?
- can determine whether its linked to damage at level of vertebrae or a peripheral nerve type damage
