Helicine arteries of penis
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| Artery: Helicine arteries of penis | |
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| Diagram of the arteries of the penis. | |
| Latin | arteriae helicinae penis |
| Gray's | subject #262 1251 |
| Dorlands / Elsevier |
a_61/12154468 |
On entering the cavernous structure from the Deep_artery_of_the_penis the arteries divide into branches, which are supported and enclosed by the trabeculae. Some of these arteries end in a capillary net-work, the branches of which open directly into the cavernous spaces; others assume a tendril-like appearance, and form convoluted and somewhat dilated vessels, which were named by Müller helicine arteries.
These arteries have two unique features: an intimal cuhsion and valves. Sympathetic stimulation maintains a tonic contractile state of the intimal cushion, smooth muscle lying in the center of the artery. This keeps the artery coiled and little blood flow occurs, instead routing to arteriovenous shunts to the deep dorsal vein. Parasympathetic stimulation removes the tonic state and allows vasodilation of the intimal cushion. Blood now pools in the corpus cavernosa, resulting in erection. The valves prevent backflow in the now tortuous route through the cavernosa.
- Remember the mnemonic PPSS: parasympathetic points, sympathetic shoots.
This parasympathetic relaxation response is mediated by a release of NO and is the primary target of Viagra. Viagra inhibits a key phosphodiesterase that reduces the effect of NO. NO binds to the receptors of the enzyme guanylate cyclase which results in increased levels of cGMP. cGMP has a very short half-life, and blocking PDE5 results in vasodilation even with small amounts of NO stimulation.
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