general, depends on the organ's position relative to the pelvic pain line. An organ, or part of an organ, in the pelvis is said to be "above the pelvic pain line" if it is in contact with the peritoneum, except in the case of the large intestine, where the pelvic pain line is said to be located in the middle of the sigmoid colon. GVA fibers from structures above the pain line follow the course of the sympathetic efferent fibers, and GVA fibers from structures below the pain line follow the course of the parasympathetic efferents. Pain from the latter fibers is less likely to be consciously experienced. Neurotransmitters For many of these visceral afferents, their endings in the periphery and in the spinal cord contain substance P and other neuropeptides of the tachykinin family, such as neurokinin A and neurokinin B, specifically in the sympathetic portion of these fibres. See also General somatic afferent fibers General visceral efferent fibers Referred pain References Peripheral nervous system