lower limb nerves and vessels Flashcards
What do the posterior divisions of the spinal nerves supply? Why?
Anterior compartments
Where does the femoral nerve enter the thigh?
comes through into thigh below inguinal ligament in femoral triangle
what does the femoral nerve supply?
anterior compartment of thigh and iliopsoas
has anterior cutaneous branch which innervates most of ant thigh
what is the terminal branch of the femoral nerve?
saphenous nerve - sensory to medial aspect of leg
what spinal nerves make up the femoral nerve?
L2,3,4
describe the path of the sciatic nerve
usually comes out of the greater sciatic foramen below piriformis
what does the sciatic nerve supply?
- posterior compartment of thigh
- all muscles below the knee via tibial and common peroneal branches
- supplies hamstrings
- some sensory branches to back of thigh
what spinal nerves form the sciatic nerve?
formed from lumbosacral trunk (L3,4,5) and sacral nerves S1,2,3
describe the passage of the obtruator nerve
passes through obtruator foramen
what does the obtruator nerve supply?
- medial (adductor) compartment of thigh
- supplies patch of skin on medial thigh superior to knee
what spinal nerves form the obtruator nerve?
- lumbar plexus
- L2,3,4
describe the passage of the inferior gluteal nerve
passes through greater sciatic foramen with the inferior gluteal artery BELOW piriformis
what does the inferior gluteal nerve innervate?
gluteus maximus
what spinal nerves make up the inferior gluteal nerve?
L5-S2
describe the passage of the superior gluteal nerve
passes through greater sciatic foramen with superior gluteal artery ABOVE piriformis
what does the superior gluteal nerve innervate?
- gluteus minimus and medius
- tensor fasciae latae
what spinal nerves make up the superior gluteal nerve?
L4-S1
describe the passage of the tibial nerve
- forms from sciatic nerve in popliteal fossa
- passes down intercondylar eminence
- passes along shaft of tibia
- then crosses behind medial malleolus
- forms medial and lateral plantar nerves
what does the tibial nerve innervate?
- post compartment of leg
- most intrinsic muscles of foot
- sensory to back of leg, sole of foot
what spinal nerves make up the tibial nerve?
L4-S3
describe the passage of the common peroneal nerve
- froms from sciatic nerve
- crosses lateral side of knee
- passes behind head of fibula
- crosses anteriorly to give off a deep and superficial peroneal branch
- also gives off sural communicating branch
what does the common peroneal nerve supply?
- anterior and lateral compartments of leg
- sensory to anterior and lateral aspects of leg and dorsum of foot
describe the passage of the deep peroneal
- passes down interosseus membrane
- ends up with its terminal branches innervating a little V shape, half of 1st and 2nd digits
what does the deep peroneal innervate?
anterior compartment of leg
what spinal nerves make up the deep peroneal?
L4-S1
describe the passage of the superficial peroneal
passes down lateral shaft of fibula
what does the superficial peroneal innervate?
- lateral compartment of leg
- terminal branch is cutaneous supply to dorsum of foot
what branches make up the superficial peroneal?
L5-S1
which area of the skin does the post cutaneous nerve of thigh innervate?
area from just below buttock to end of the popliteal fossa in middle
S1,2
What area of skin does the saphenous nerve innervate?
medial anterior and post part of leg
what part of the skin does the lateral sural cutaneous nerve supply?
lateral part of leg on ant and post parts
what area of skin does the sural nerve supply?
small patch of skin on posterior part of leg, in midline
what muscles in particular does the femoral nerve supply?
Anterior compartment:
- psoas and illiacus
- pectineus
- sartorius
- rectus femoris
- vastus medialis
- vastus intermedius
- vastus lateralis
what muscles in particular does the obtruator nerve supply?
Medial compartment:
- obtruator externus
- adductor brevis
- adductor longus
- part of adductor magnus
- gracilis
What muscles in particular does the sciatic nerve supply?
Posterior compartment:
- biceps femoris
- semimembranosus
- semitendinosus
- part of adductor magnus
What muscles in particular does the deep peroneal nerve supply?
- extensor digitorum longus
- extensor hallucis longus
- tibialis anterior
- peroneus tertius
- extensor digitorum brevis
What muscles in particular does the superficial nerve supply?
- peroneus longus
- peroneus brevis
describe injury to the femoral nerve
rarely damaged
commonly during hip replacements
describe injury to the lateral cutaneous nerve of the thigh
can be compressed when it passes 2cm medial to ASIS at level of inguinal ligament
–> meralgia paraesthetica
describe injury to the obtruator nerve
rarely
pain in thei region can indicate malignant disease in pelvis
describe injury to the superior gluteal nerve
Tredelenberg gait
mostly damaged in hip replacements
describe injury to the sciatic nerve
damaged in hip replacement, trauma, pelvic disease
describe injury to the common peroneal nerve
vulnerable to damage at hip and level of fibular neck
damaged by trauma, knee replacement, external pressure
describe injury to the saphenous nerve
common, can be damaged at medial malleolus (after varicose vein surgery) or at level of knee (e.g. ACL surgery)
when assessing nerve function, what 4 things should you check?
- motor function - loss of some movements inidicates which part of spinal cord is damaged
- sensory function
- reflex function - test monosynaptic reflexes like patellar tendon reflex
- autonomic function - sweating/redness
What would you see if someone had a prolapsed intervertebral disc at L5-S1?
- loss of eversion
- loss of sensation of outer border of foot
- loss of ankle jerk (S1)
- minimal autonomic loss
what would you see if someone had injury to the common peroneal nerve at fibular neck?
- no dorsiflexion of foot or eversion (foot drop)
- loss of sensation on anterior leg, dorsum of foot
- no reflexive losses
- minimal autonomic loss
describe how the abdo aorta becomes the femoral artery
abdo aorta > common iliacs > external/internal iliacs > external iliac becomes femoral at mid inguinal point
what does the femoral artery give off?
- profunda femoris
- 3 circumflex branches
what are the 4 branches of the femoral artery in the thigh just below the inguinal ligament?
- superficial circumflex iliac
- superficial epigastric
- superficial external pudendal artery
- deep external pudendal artery
how does the femoral artery become the popliteal artery?
- femoral artery passes down femoral triangle and femoral canal
- then passes through adductor hiatus to become popliteal artery in popliteal fossa
where would you palpate the femoral artery?
mid inguinal point (half way b/ ASIS and PS)
describe what happens to the popliteal artery
gives off 4 genicular branches (superior, inferior, lateral, medial)
it trifurcates into anterior and posterior tibial arteries
this immediately bifurcates into posterior tibial and peroneal
describe the passage of the anterior tibial artery
descends down interosseous membrane
crosses ankle in midline to bcome dorsalis pedis artery
where is the anterior tibial artery palpable?
- in the V b/ 1st and 2nd digits
- between tendons of EHL and EDL
what does the ant tibial artery supply?
ant compartment of leg
describe the path of the post tibial artery
descends down leg behind shaft of tibia
crosses posterior to medial malleolus
where is the post tibial artery palpable?
half way b/ heel and medial malleolus
what does the post tibial artery supply?
- supply posterior compartment of leg
- contributes to plantar arches via lateral and medial plantar arteries
describe the passage of the peroneal artery?
crosses down shaft of fibula
crosses anteriorly to lateral malleolus
what does the peroneal artery supply?
lateral compartment
describe the passage of the long saphenous vein?
- formed from dorsal venous arch
- crosses in front of medial malleolus
- up ant medial side of leg and thigh where it joins femoral
describe the passage of the short saphenous vein
- forms from plantar venous network
- runs up in b/ heads of gastrocnemius
- drains into popliteal vein by perforating popliteal fossa
what are perforating veins?
veins from superficial venous system that drain into deep venous system
what happens when valves of the perforating veins fail?
backflow into them
–> protrude into skin = varicose veins
what is a saphenous cut down?
- extreme trauma to get IV access
- incision 2cm proximal and lateral to medial malleolus
what is compartment syndrome?
- leg separated into compartments
- if pressure builds up in one
- increased pressure in confined compartment can cause ischaemia–> pain