lumbar and sacral nerve branch .

anatomy and autonomic autonomous axon biology body brain brainstem branch cardiac cardiovascular cells central cerebellum cervical communication control cord cranial diagram doctor espinal excitement external facial friendly health human illustration intelligence involuntary issue limbic lumbar man marrow medicine nerve nerves nervous neurology neuron neurons ocular order organ parasympathetic sacral sacrum science sensory somatic spinal spine structure synapse system thoracic transmission visceral voluntary walk woman