Anatomy, Bony Pelvis and Lower Limb: Nerves

The nerves of the pelvis and lower limbs originate from sympathetic, parasympathetic, and somatic nerves. The sympathetic component comes from roots T12 through L2 and the parasympathetic from roots S2 through S4. The sympathetic component reaches the pelvis through the superior hypogastric plexus. These nerves are known as sacral splanchnic nerves. The parasympathetic components are referred to as pelvic splanchnic nerves. Somatic innervation for the pelvis arises from nerve roots S2 through S4. Somatic innervation contains two parts, motor and sensory. Afferent fibers carry sensory information while efferent fibers carry motor. Nerve roots L2 through L4 and L4 through S3 supply all the motor and some sensory information for the lower limbs. Generally, nerves with motor information supply all muscles contained within a given compartment. For example, The tibial nerve supplies the muscles that are within the posterior compartment of the lower extremities. The cutaneous sensation is in a dermatomal distribution.