Innervation of the Lower Limb Flashcards
major functions of the lower limb
weight bearing
maintaining posture
locomotion
regions of the lower limb
hip (gluteal)
thigh
knee
leg
ankle
foot
key bones of the lower limb
pelvic bone
sacrum
(hip joint)
femur
(knee joint)
tibia
fibula
key bones of the foot
calcaneus
talus
metatarsals
phalanges
bones involved in joints:
hip
knee
ankle
sub-talar
metatarsophalangeal
interphalangeal (PIP and DIP)
hip: pelvis and femur
knee: femur and tibia
ankle: tibia, fibula and talus
sub-talar: talus and calcaneus
metatarsophalangeal: metatarsal and phalanges
interphalangeal: phalanges
motions at each joint
hip
knee
ankle
subtalar
hip: extra/intra rotation, abduction/adduction
knee: flexion/extension
ankle: plantar/dorsi-flexion
subtalar: inversion/eversion, adduction/abduction
nerves of the lower limb
femoral nerve
obturator nerve
sciatic nerve
tibial nerve
common peroneal nerve (deep and superficial)
femoral nerve pathway and motor supply
L2-4
arises from lumbar plexus within psoas major
passes between iliacus and psoas major muscles in the abdomen
enters thigh by passing behind inguinal ligament
supplies muscles of the anterior compartment of thigh
sensory branches of femoral nerve and the regions they supply
anterior femoral cutaneous nerve: skin on the front of thigh, knee and medial aspect of thigh
saphenous nerve: skin on the medial of the knee, leg and foot
knee jerk reflex
stretching quadricep femoris causes femoral nerve to sense it and contract quads and relax hamstrings
involves L2, L3, L4
effect of injury of femoral nerve
may occur with haematomas in iliacus muscle, surgery or pelvic fracture
loss of extension at knee joint and impaired hip flexion
sensory loss over anterior thigh, knee and medial thigh, leg and foot
obturator nerve pathway and motor supply
arises from lumbar plexus (L2-L4)
descends in psoas major muscle then along lateral pelvic wall
passes through the obturator foramen
supplies muscles in medial compartment of thigh
obturator nerve sensory supply
skin on the inferomedial aspect of the thigh
effect of injury to obturator nerve
what may cause it
weakness of thigh adduction
sensory loss over inferomedial thigh
may be caused by pelvic fractures, hip replacement surgery, obturator hernias
sciatic nerve pathway and motor supply
arises from L4-S3 from lumbosacral plexus
leaves pelvis via greater sciatic foramen and enters gluteal region
descends into posterior compartment of thigh
divides near the back of the knee into tibial nerve and common peroneal nerve
supplies muscles of posterior compartment of thigh
sensory supply at posterior thigh area
where does the nerve originate
posterior cutaneous nerve
arises from S1-3 from sacral plexus
branches from sciatic nerve
effect of injury to sciatic nerve
possible causes
loss of knee flexion and impaired hip extension
loss of dorsiflexion and plantarflexion, inversion and eversion of the foot
sensory loss over lateral leg and whole foot
injections to gluteus maximus, hip trauma or surgery, prolonged pressure due to immobility
tibial nerve pathway and motor supply
descends through the popliteal fossa
passes into the back of the leg
gives out a branch into sural nerve
tibial nerve passes behind medial malleolus into the foot and divides into plantar nerves
supplies all the muscles in the posterior compartment
effect of injury to tibial nerve
possible causes
loss of plantarflexion of the foot and flexion of the toes
sensory loss over posterolateral leg, sole and lateral aspect of foot
may be caused by compression due to Baker’s cyst or foot and ankle trauma
common peroneal nerve pathway
L4-S2
arises as terminal portion of sciatic nerve in popliteal fossa
descends laterally and winds around neck of fibula
divides into superficial and deep peroneal nerves
superficial peroneal nerve motor supply
muscles of lateral compartment of leg
deep peroneal nerve motor supply
muscles of anterior compartment of leg
superficial and deep peroneal nerve sensory supply
superficial: skin of anterolateral leg and dorsum of the foot (top)
except between first two toes
deep: skin of the space between first two toes
common peroneal nerve effect of injury
common causes
foot drop: loss of dorsiflexion and eversion
loss of sensation on anterolateral aspect of leg and dorsum of foot
fracture of neck of the fibula
