Apparently there is a completely separate spinal cord reflex where direct penile stimulation leads to an erection. This reflex only needs an intact arc in S2-S4, so as long as this region is not injured, an erection can still occur. However, with transection at C8, then the psychogenic erection reflex cannot occur, as this requires descending fibers from the cortex.
lsmarshallJust saw a good summary of nerves/vessels involved saying, "pelvic parasympathetic fibers from S2-S4 can cause cavernous arteriole vasodilation via the cavernous nerve without of central stimulation."+32019-05-28T23:07:09Z
seagullS2-3-4 keeps the penis off the floor+92019-06-08T15:12:25Z
drdoomModifying @seagull into iambic pentameter: “S2, S3, and Number 4 / keeps the big ole penis / off the floor”+2019-06-24T09:14:04Z
Apparently theres role of sympathetic system in psychogenic erection and its comes from T11-L2. So if patient have transaction at L5 they lose reflex erection but still retain psychogenic one.
ABove T9 transaction cause loss of psychogenic erection
submitted by sattanki(32), 2019-05-20T10:04:38Z
Apparently there is a completely separate spinal cord reflex where direct penile stimulation leads to an erection. This reflex only needs an intact arc in S2-S4, so as long as this region is not injured, an erection can still occur. However, with transection at C8, then the psychogenic erection reflex cannot occur, as this requires descending fibers from the cortex.