The belly button, or umbilicus, is a scar on the abdomen marking where the umbilical cord once connected the fetus to the placenta. In adults, this area consists of several protective tissue layers before the internal organs begin. Understanding the structures deep to this surface requires exploring the abdominal cavity to clarify which organs are most commonly found directly behind the navel.
Understanding the Abdominal Wall Layers
Before reaching any internal organs, several protective layers of the abdominal wall must be passed through. The outermost layer is the skin, followed by subcutaneous tissue containing fat and fascia. Below the umbilicus, this subcutaneous fascia divides into two distinct layers: the fatty Camper’s fascia and the deeper, membranous Scarpa’s fascia.
Deep to the fatty layer lies the abdominal musculature, primarily the vertically running rectus abdominis muscle, encased by the rectus sheath. The midline where the two rectus abdominis muscles meet is the linea alba, a line of dense connective tissue that is thin at the umbilicus. The final layer before the internal cavity is the parietal peritoneum, a thin membrane lining the abdominal wall that separates the muscle layers from the digestive organs.
The Primary Organs Directly Behind the Navel
The structures most consistently found directly behind the umbilicus are coils of the small intestine. Specifically, sections of the jejunum and ileum occupy the central abdominal space. These organs are highly mobile within the abdominal cavity, suspended by the mesentery, a fan-shaped fold of tissue.
Due to this mobility, the exact loop of intestine behind the navel can shift depending on body position and posture. The transverse colon, the middle segment of the large intestine, may also cross the area, though it is often situated slightly superiorly. The central location of the small intestine explains why pain originating from this organ system, often called “midgut pain,” is frequently felt in the umbilical area.
Major Structures in the Immediate Abdominal Vicinity
While the small intestine is the primary occupant posterior to the navel, several other major structures are located nearby, slightly deeper or to the sides. The abdominal aorta and the inferior vena cava, the two largest blood vessels, run vertically along the posterior abdominal wall behind the intestinal mass. These vessels are significantly deeper than the navel but are part of the central anatomy of the region.
The umbilicus also corresponds to the region that includes the head of the pancreas and the duodenum, the first part of the small intestine. The lower edge of the liver, particularly the round ligament (a remnant of the fetal umbilical vein), attaches to the posterior aspect of the umbilicus. The lower pole of the kidneys can also extend into the general area surrounding the umbilicus, making the region a dense crossroads of anatomical structures.
Health Conditions Specific to the Umbilical Area
The umbilicus is a natural point of weakness in the abdominal wall, making it a common site for certain health conditions. The most frequent condition is an umbilical hernia, which occurs when a portion of the intestine or fat pushes through the former umbilical ring. In children, these hernias often close spontaneously by age five, but in adults, they are acquired due to increased abdominal pressure from factors like multiple pregnancies or obesity.
Another set of conditions involves remnants of fetal development, particularly the urachus, a channel connecting the fetal bladder to the umbilicus. In adults, this channel should become a solid fibrous cord called the median umbilical ligament. If it fails to close completely, it can lead to anomalies like cysts or a patent urachus, which may cause pain or discharge from the navel.