Editing Lordosis behavior (section)

==Neurobiology==

The lordosis [[reflex arc]] is hardwired in the spinal cord, at the level of the lumbar and sacral [[Vertebra (anatomy)|vertebrae]] (L1, L2, L5, L6 and S1).<ref name="pfaff1994">Pfaff D. W. , Schwartz-Giblin S., Maccarthy M. M., Kow L-M (1994). "Cellular and molecular mechanisms of female reproductive behaviors", in Knobil E., Neill J. D. ''The physiology of reproduction'', Raven Press, 2nd edition.</ref> In the brain, several regions modulate the lordosis reflex. The [[vestibular nuclei]] and the [[cerebellum]], via the vestibular tract, send information which makes it possible to coordinate the lordosis reflex with [[Equilibrioception|postural balance]]. More importantly, the ventromedial [[hypothalamus]] sends projections that inhibit the reflex at the spinal level, so it is not activated at all times.<ref name="Kow2007">{{cite journal | author = Kow L.M.|author2=Florea C.|author3=Schwanzel-Fukuda M.|author4=Devidze N.|author5=Kami K.H.|author6=Lee A.|author7=Zhou J.|author8=Maclaughlin D.|author9=Donahoe P.|author10=Pfaff D. | title = Development of a Sexually Differentiated Behavior and Its Underlying CNS Arousal Functions | year = 2007 | journal = Curr. Top. Dev. Biol. | volume = 79 | pages = 37–59 | doi = 10.1016/S0070-2153(06)79002-0 | pmid = 17498546 | series = Current Topics in Developmental Biology | isbn = 9780123739131 }}</ref> Sex hormones control reproduction and coordinate sexual activity with the physiological state. Schematically, at the [[breeding season]], and when an [[ovum]] is available, hormones (especially [[estrogen]]) simultaneously induce [[ovulation]] and [[estrus]] (heat). Under the action of estrogen in the hypothalamus, the lordosis reflex is uninhibited.<ref name="flanagan">{{cite journal | author = Flanagan-Cato L.M. | year = 2011 | title = Sex differences in the neural circuit that mediates female sexual receptivity | journal = Frontiers in Neuroendocrinology | volume = 32 | issue = 2| pages = 124–136 | pmc=3085563 | pmid=21338620 | doi=10.1016/j.yfrne.2011.02.008}}</ref> The female is ready for copulation and [[fertilization]].

When a male mammal mounts the female, tactile stimuli on the flanks, the [[perineum]] and the [[Rump (animal)|rump]] of the female are transmitted via the [[sensory nerve]]s in the [[spinal cord]]. In the spinal cord and lower [[brainstem]], they are integrated with the information coming from the brain, and then, in general, a [[Action potential|nerve impulse]] is transmitted to the [[muscle]]s via the [[motor nerve]]s. The contraction of the longissimus and transverso-spinalis muscles causes the ventral arching of the vertebral column.<ref name="pfaff1994"/>