Nerves and blood supply of the lower limb Flashcards
What is a plexus
a plexus is a network, latin- plecture, means to intertwine- forms peripheral nerves.
what is the lumbar plexus
L1-L5 at each level a peripheral spine nerve leaves, this produces neuro material which goes into the plexus, this then exits as a nerve
what is a sacral plexus
Sacral plexus- S1-S5
where is the spinal cord from
from the cervical region down to L1,2.
what is the cauda equina
conus medullaris between L1 and L2, this goes to the cauda equina. This forms peripheral nerve that exit via intervertebral foramen, through the sacrum they exit via anterior sacral foramen- joint sacral plexus
peripheral spinal nerves
emerges from spinal cord via a ventral (front) and dorsal (back) root. Dorsal root- carries sensory information to the spinal cord (dorsal root ganglia- contain the sensory cell bodies), ventral root- carries motor information from the anterior horn cells
what are the anterior horn cells
to do with motor response
what are dermatomes
area of the skin supplied by a single spinal nerve of spinal cord level
what does each spinal nerve do
each spinal nerve carries somatic sensory information from specific areas of skin,
outlets from the pelvis- inguinal tunnel
femoral nerve- L2,L3,L4
outlets from the pelvis- greater sciatic foramen
sciatic nerve, gluteal nerve
outlets from the pelvis- obturator canal
obturator nerve
outlets from the pelvis- peripheral nerves
peripheral nerves from different origins (L1,L2 etc) join together to form plexus, these join together to share information and form a single nerve
Main branches of the lumbosacral plexus
femoral nerve- saphenous nerve, obturator nerve, sciatic nerve- tibial nerve (medial and lateral plantar nerve), common peroneal nerve (deep and superficial), superior and inferior gluteal nerves
what is the lumbar plexus
ventral rami of spinal nerves of T12-L4, lies within the posterior part of the psoas major, supplies the abdominal wall and lower extremities
branches of the lumbar plexus- muscle branches
femoral nerve L2,L3,L4
Obturator nerve- L2,L3,L4
branches of the lumbar plexus- other nerves
iliohypogastric, ilio-inguinal, genitofemoral, lateral cutaneous nerve of thigh
femoral nerve
carries information from the anterior rami of L2-L4 and runs through psoas major and under the inguinal ligament lateral to the femoral artery and vein, to enter the femoral triangle on the anteromedial aspect of the thigh- splits into anterior and posterior divisions
femoral nerve- branches into pelvis and distal to the inguinal ligament
iliacus, pectineus, inguinal ligament- saphenous nerve- cutaneous, supplying skin of the anteromedial aspect of leg and medial aspect of the foot
anterior divisions of the femoral nerve
sartorius, intermediate cutaneous nerve of thigh, medial cutaneous nerve of thigh
posterior division of femoral nerve
saphenous nerve and quadriceps
obturator nerve
originates from ventral rami of L2-L4, runs through psoas major, emerging at medial border; passes down on obturator internus; exits pelvis through the obturator foramen
what does the obturator nerve supply
adductor group, gracilis, pectineus obturator externus, medial side of thigh, knee and hip joint
iliohypogastric nerve
originates from L1, innervates- skin over lower abdominal above the pubis and lower back and hip, transverse abdominis, inter and external obliques
genitofemoral nerve
originates at L1-L2 innervates- anterior thigh inferior to inguinal region
ilio-inguinal nerve
originates L1, innervates- skin of external genitalia, proximal medial aspect of thigh, transverse abdominis, obliques
lateral cutaneous nerve of thigh
originates L2-L3- passes under the inguinal ligament medial to the ASIS, innervates- lateral skin of thigh
what is meralgia paresthetica
it is a condition characterized by tingling, numbness and burning pain in the outer part of your thigh. The condition is caused by compression of the lateral femoral cutaneous nerve
what is the sacral plexus
it arises from ventral rami of S1-S4, contribution from lumbar plexus (L4-L5), lies anterior to the piriformis muscle and posterior pelvic wall, exits via the greater sciatic notch
branches of the sacral plexus
sciatic nerve, superior/ inferior gluteal nerve, quadratus femoris and gemellus inf, obturator internus and gemellus sup, piriformis
sciatic nerve
largest nerve in the body- L4-S3, consists of 2 nerve bundles- tibial nerve and common peroneal nerve, leaves pelvis via greater sciatic notch, exits just inferior to piriformis
sciatic nerve innervates
hamstrings, adductor magnus
sciatic nerve route
passess vertically down the back of the thigh, lying on adductor magnus, covered by long head bicep femoris. it divides into common peroneal (wraps around the head of fibula) and tibial nerve (straight through knee joint) between hip and popliteal fossa
superior gluteal nerve
fibres from L4,L5,S1, innervates- gluteus med and min, and TFL
inferior gluteal nerve
fibres from L5,S1,S2, innervates gluteus maximus
tibial nerve
fibres from L4-S3, innervates popliteus, plantaris, gastrocnemius, soleus, tibialis posterior, FHL, FDL, it gives a branch to the sural nerve
what does the tibial nerve split into
medial and lateral plantar nerves
what is the sural nervw
sensory nerve that supplies the skin over the lateral side of the lower third of leg, derives from branches from both tibial and common peroneal nerve
lateral plantar nerve innervates
remaining deep muscles, lumbricals (2,3,4), interossei, adductor digiti minimis, adductor hallucis, sensory cutaneous- 5th toe and lateral half of 4th toe
medial plantar nerve innervates
FDB, FHB, 1st Lumbrical, sensory cutaneous- skin medial to big toe, skin between 1st and 4th toes
common peroneal nerve
fibres from L4-S2, wraps around neck of fibula, splits into deep and superficial peroneal nerves
superficial peroneal nerve
peroneus longus/ peroneus brevis- lateral compartment, skin over lateral leg , splits into medial and lateral branches
deep peroneal nerve
innervates dorsiflexors, tibialis anterior, EHL, EDL, peroneus tertius, ankle joint
deep peroneal nerve lateral branch
EDB/ 2nd dorsal interossei, tarsal and MTP joint
deep peroneal nerve medial branch
1st dorsal interossei, 1st tarsal and MTP joint, skin between big and second toe
femoral artery
this is a major artery supplying the lower limb which is the contribution of the external iliac artery, the artery continues down the thigh in the femoral canal, continuous in the adductor hiatus and then becomes the popliteal artery posterior to knee
what does the external iliac artery become the femoral. artery
as the vessel passes under the inguinal ligament and enters the femoral triangle
popliteal artery
this is the major artery that supplies the leg and foot and enters the posterior compartment of the leg from the popliteal fossa. in the posterior compartment the popliteal artery divides into the anterior tibial artery and posterior tibial artery
where can the popliteal artery be palpated
in the popliteal fossa
lower limb arterial supply
popliteal artery splits into- posterior and anterior tibial arteries, and dorsal pedis
anterior and posterior tibial artery
anterior- anterior aspect ankle between EHL and 1st tendon of EDL
posterior- enters the foot through the tarsal tunnel on the medial side of the ankle and posterior medial malleolus
what is the dorsalis pedis
this is the continuation of the anterior tibial artery as it crosses the ankle joint. the pulse could be palpated on the dorsal aspect of the foot palpitating the vessel against the tarsal bone between the tendons of FHL and FDL to second toe
