As I was fishing some lint out of my belly button this morning, I began to contemplate my navel. Literally.
I wasn’t able to easily find any Web sites to answer my questions, nor did a topic search find any applicable columns from Cecil, so I turn to my fellow Dopers and possibly Cecil, himself:
Is my belly button still hooked up to anything inside me? If there’s still a connection to the bloodstream why isn’t the belly button used as a convenient “port” for intraveneous drugs? Or is it one of those “use it or lose it” things where the plumbing has since withered away?
Well, since it used to connect to the placenta via the umbilical cord, and that little bit of umbilical cord has since disappeared, I would assume any “plumbing” has long since gone kaput. AFAIK, the bellybutton is merely a scar from the place the umbilical cord dropped from. Some scars are concave, others convex (innie and outie). I think if you went far enough back in there, you would simply find stomach skin (perhaps it would be more sensitive skin way in there) with no exceptional features on the surface or below.
You’ve got it - the plumbing’s gone. In a fetus, the umbilical cord contains two arteries and one vein, which connect to the fetus’s iliac arteries and liver, respectively, and circulate blood into and out of the placenta. In a newborn infant, the umbilical vessels can indeed be used to administer drugs and fluids or to withdraw blood for testing. But as the child grows, those blood vessels (no longer useful after birth, since the placenta’s gone) swftly close off and eventually are reduced to narrow bands of fibrous tissue. There’s nothing functional attached to the inside side of your umbilicus now, just a little bit of fibrous tissue connecting it to your liver.
what’s directly behind your navel, organwise, anyways? i’m thinking just the intestines, but a guy i knew said he heard one could kill themselves by stabbing themself in the belly button. he was probably just full of crap though.
For a related question, is there any sort of . . . strange . . . nerve wiring going on with the bellybutton? I ask because if I scratch my bellybutton, I feel a vague itching sensation somewhere behind my general groin area, several inches down.
In most cases, a Meckel’s diverticulum is just a little outpouching off the small bowel, and doesn’t actually connect to the umbilicus (although it can). Another bit of residual plumbing sometimes found connected to the umbilicus is a patent urachus (the urachus is a tube-like extension from the top of the bladder that runs along the abdominal wall to the umbilical cord, which usually closes off completely during fetal development).
Did you know why a Meckel’s diverticulum sometimes develops? At one point during fetal development, the entire bowel is pulled outside the abdominal cavity (more or less being drawn into the base of the umbilical cord). The bowel then slowly retracts back into the abdominal cavity, rotating into its final adult position as it does so. Then the opening through which it re-enters the body closes over to form the anterior abdominal wall. An umbilical hernia, which many babies have at birth, occurrs when this closing process isn’t quite complete. In rare cases, the bowel fails to retract properly, and a baby can be born with its intestines partially protruding outside its body in a membranous sac (omphalocele), or even with no anterior abdominal wall at all (gastroschisis). Anyway, a Meckel’s diverticulum forms at the point where the connection between the bowel and the umbilical cord was located during the whole withdrawal/retraction sequence; again, the tube connecting the two structures doesn’t quite close off completely, leaving this little pouch behind as a reminder of its former existence.
The greatest portion of your liver is on the right side of your body, yes - but the left lobe does cross the midline, and the vessels entering and exiting the liver are all located close to the midline. So the connection between the umbilicus and the liver runs frum the umbilicus slightly up and slightly to the right.
My guess: By poking into your navel and pressing almost directly on the abominal muscle lining, you are creating a temporary inguinal hernia. The scrotum is a large open spot in that muscle wall, and thus the likely place where a bulge will occur in reaction to the pressure you are putting on your intestines.
There is a nervous connection, yes - the umbilical arteries in the fetus run down the anterior abdominal wall and into the pelvis, where they connect to the iliac arteries. The iliac arteries give rise to the femoral arteries, which exit the pelvis in the groin region and feed blood into your legs. Several small nerves branches follow the general course of the umbilical arteries along the lower abdominal wall. Whn you scratch your bellybutton, you’re probably stimulating those nerves, which refer the sensation into your groin.
Immediately behind the umbilicus, it’s just the intestines. But running down the midline of your abdomen along the posterior wall (just in front of your spine) lies your aorta and your inferior vena cava - the two biggest blood vessels in the body. If you stab yourself in the umbilicus deeply enough (4-5 inches or so), you can easily hit those blood vessels, and you’ll bleed to death VERY quickly. So your friend’s story is quite believable.
Right behind your umbilicus is the rectus sheath of connective tissue which connect the muscles of the anterior abdominal wall. This forms the linea alba – the middle vertical line in the abdominal muscles. Beneath that is the transversalis fascia, another layer of connective tissue, and then the peritoneum.
From the umbilicus comes folds in the peritoneum called the medial umbilical ligaments. These used to contain the umbilical artery (left medial ligament), vein (right ligament) and urachus (median ligament, with paraumbilical veins), which have sclerosed into fibrous tissue. The median ligament forms the tip of the bladder. Lateral to these are two folds in the peritoneum which contain the functional epigastric arteries and veins.
When your bladder is really really full, it stretches into a roughly triangular shape, with the apex behind the umbilicus. If the prostate is so enlarged that one cannot introduce a urinary catheter in the normal course, one can introduce a suprapubic catheter right below the umbilicus using a large bore needle (basically).
The innervation of the umbilicus is provided by the nerves coming off of the tenth thoracic vertebrate (T10). The testes form high in the abdominal cavity and descend through the inguinal canal until the reach the scrotum in the 7th month of pregnancy. They are also innervated from nerves of T10, and carry some branches down with them as they descend. Cross talk between the areas of the T10 dermatome are likely, so that is why sensation is often referred from the groin into the umbilicus and vice versa. Think about getting kicked in the nuts – it is more of an abdominal than a groin feeling.
Back to the “itching sensation” and the remaining nerves, if those nerves also shrink just like the bloodvessels taht evnetually go kaput as the child ages, that also explains by babies and small children have such ticklish tummies, but why that disappears whereas one’s armpits remain ticklish. (And, for some people, soles of feet, too.)
Interesting, A Curious Writer, that may give us a simple test for Meckle’s diverticulum. The link says 1 in 50 have not lost the connecting structure, and 1 in 25 of those have problems with it later.
When I was tested for a Meckle’s fifteen years ago (my red blood cell count was so low, they thought they’d screwed up the test), I had to lay for an hour between two one ton plates, squashed like chicken salad, while a team of doctors viewed a monitor depicting a glow that slowly outlined my innards.