In the limbs, sensory fibers are distributed to an area further from the axis of the body than the motor fibers of the corresponding root. The skin innervation areas encroach on each other, which justifies the anesthesia of adjacent nerves.
Bones and joints are the main target for postoperative analgesia.
As a rule, joints receive innervation from the same nerves that innervate muscles that act on them.
Anterior aspect: deep peroneal nerve.
Posterior and medial aspects: tibial nerve.
Figure 140-1. Lower Limb Dermatomes, Myotomes, and Sclerotomes
Adapted from Jochum D and Delaunay L, with permission from AstraZeneca France.
Figure 140-2. Hip Joint InnervationAnterior portion of the joint capsule: (1) branch of the femoral nerve (L1–L4) along the iliopsoas muscle.Anteromedial portion: (2) a branch of the obturator nerve (L1–L4).Posterior portion: (3) branches of the sciatic nerve.Posteromedial portion: ramus from the nerve of the quadratus femoris muscle (L5–S2).Posterolateral portion: rami of the superior gluteal nerve (L4–S1).
Figure 140-3. Knee Joint InnervationAnterior and anteromedial aspects: deep branches of the femoral nerve (1).Posterior and inferolateral aspects: sciatic nerve (2).Posterior aspect: contribution of articular rami of the deep branch of the obturator nerve (3).