Flashcards in Sciatic nerve Deck (16):
What are the nerve roots, motor and sensory function of the sciatic nerve?
Motor: innervates muscles of posterior thigh & hamstring of adductor magnus, terminal branch innervates muscles of leg & foot
Sensory: indirectly innervate (terminal branches) skin of lateral leg, heel, dorsal & plantar surfaces of foot
What are the significance of the sciatic nerve?
the largest nerve of the body
major nerve of lower limb
thick flat band - 2cm
What is the sciatic nerve derived from and name the beginning of it's anatomical course
from lumbosacral plexus
leaves pelvis to enter gluteal region via sciatic foramen
travels down thigh inferior to piriformis muscle, inferolaterally
Describe the anatomical course of the sciatic nerve from the gluteal region to the thigh
after passing posterior to gluteus minimis and piriformis, the sciatic nerve then crosses the posterior surface of the superior gemellus, obturatus externus, inferior gemellus, obturator internus, quadratus femoris (all deep muscles of gluteal region), entering posterior thigh by passing deep to long head of biceps femoris
What happens once the nerve is in the posterior thigh?
gives rise to nerve branches innervating the hamstring muscles and part of the adductor magnus
when nerve enters popliteal region, it bifurcates into the tibial and common fibular nerves
describe the sciatic nerve
2 individual nerve bundles (common fibular & tibial)
normally separated at apex of popliteal fossa
can separate as they leave the pelvis in some people
careful to avoid the sciatic nerve - split gluteal region into 4 sections by 2 lines
vertical line: from highest point of iliac crest
horizontal: passes vertical line halfway between highest point of iliac crest and ischial tuberosity (sitting bones)
inject through the upper lateral quadrant as the sciatic nerve runs through the lower medial quadrant
motor functions of sciatic nerve
muscles of posterior thigh, hamstring of adductor magnus
What are the 2 terminal branches of the sciatic nerve?
what are the motor functions of tibial nerve?
muscles of the posterior leg (calf muscles)
some intrinsic muscles of the leg
What are the motor functions of the common fibular nerve?
muscles of anterior and lateral leg
remaining instrinsic foot muscles not innervated by the tibial muscle
including the terminal branches (tibial & common fibular nerve) which areas of the lower limb is the sciatic nerve responsible for motor functions of?
posterior thigh, entire leg & entire foot
does the sciatic nerve have any sensory functions?
not directly, but indirectly through the common fibular and tibial nerves
sensory innervation of the tibial nerve
postero-lateral & antero-lateral sides of the leg, plantar surface of foot (sole)
sensory function of common fibular nerve
lateral leg & dorsal foot (top of foot)