- See:
Innervation of the Leg and Foot :
- Discussion:
- arises from femoral nerve in femoral triangle and descends through it on
lateral side of the femoral vessels to enter the adductor canal.
- it crosses the vessels obliquely to lie on their medial side in front of lower end
of
adductor magnus
muscle;
- nerve continues its descent on medial side of knee, pierces fascia lata between
tendons of
sartorius &
gracilis, & then passes downward on the medial
side of leg close to greater saphenous
vein;
- at lower end of canal, it leaves femoral vessels & gives off its infrapatellar branch,
& runs onward to supply skin over medial side and front of knee and
patellar ligament;
- saphenous nerve lies posterior to
sartorius in 60%;
- in the lower leg, it subdivides:
- one branch follows the medial tibial border to the level of the ankle.
- larger passes anterior to medial malleolus to innervate skin on medial
and dorsal side foot;
- Changes in Nerve Position w/ Knee Flexion:
- in extension, saphenous nerve & all infrapatellar branches cross medial joint
line anterior to posteromedial corner & are located 2-3 cm anterior to
semitendinosus tendon;
- in flexed knee, saphenous nerve and its branches cross medial joint line at, or
slightly behind, posteromedial corner of knee;
- Saphenous nerve block:
- provides anesthesia over the medial portion of foot;
- subcutaneous "field block" with continuous wheal from lateral margin of achilles tendon around the
anterior ankle to the medial margin of the achilles tendon will anesthetize all superficial nerves
of the foot: superficial peroneal, saphenous, and sural;
- references:
-
NYSORA.
-
Anesthesia UK.
Study of the infrapatellar nerve.
Arthornthurasook A, Gnew-IM K: Am J Sports Med 1988;16:57-59.
