The umbilical artery is a paired

artery An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pu ...

(with one for each half of the body) that is found in the

abdominal The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the to ...

and pelvic regions. In the

fetus A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal dev ...

, it extends into the umbilical cord.

Structure

Development

The umbilical arteries supply

deoxygenated blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the ...

from the fetus to the

placenta The placenta is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate mate ...

. Although this blood is typically referred to as deoxygenated, this blood is fetal systemic arterial blood and will have the same amount of oxygen and nutrients as blood distributed to the other fetal tissues. There are usually two umbilical arteries present together with one umbilical vein in the umbilical cord. The umbilical arteries surround the

urinary bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine ente ...

and then carry all the deoxygenated blood out of the fetus through the umbilical cord. Inside the placenta, the umbilical arteries connect with each other at a distance of approximately 5 mm from the cord insertion in what is called the ''Hyrtl anastomosis''. Subsequently, they branch into

chorionic arteries Chorionic (plate) vessels, also fetal surface vessels are blood vessels, including both arteries and veins, that carry blood through the chorion in the fetoplacental circulation. Chorionic arteries branch off the umbilical artery, and supply the ...

or ''intraplacental fetal arteries''. The umbilical arteries are actually the latter of the internal iliac arteries (anterior division of). These supply the hind limbs with

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the cir ...

and nutrients in the

. The umbilical arteries are one of two arteries in the human body, that carry deoxygenated blood, the other being the pulmonary arteries. The

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country a ...

inside the umbilical artery is approximately 50

mmHg A millimetre of mercury is a manometric unit of pressure, formerly defined as the extra pressure generated by a column of mercury one millimetre high, and currently defined as exactly pascals. It is denoted mmHg or mm Hg. Although not an ...

. Resistance to blood flow decreases during development as the artery grows wider.

After development

The umbilical artery regresses after birth. A portion obliterates to become the

medial umbilical ligament The medial umbilical ligament (or cord of umbilical artery, or obliterated umbilical artery) is a paired structure found in human anatomy. It is on the deep surface of the anterior abdominal wall In anatomy, the abdominal wall represents the bo ...

(not to be confused with the median umbilical ligament, a different structure that represents the remnant of the embryonic urachus). A portion remains open as a branch of the anterior division of the internal iliac artery. The umbilical artery is found in the

pelvis The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton). The ...

, and gives rise to the superior vesical arteries. In males, it may also give rise to the

artery to the ductus deferens The artery to the ductus deferens (deferential artery) is an artery in males that provides blood to the ductus deferens. Course The artery arises from the superior vesical artery or the inferior vesical artery, which in turn arises from the anter ...

which can be supplied by the inferior vesical artery in some individuals.

Clinical significance

A catheter may be inserted into one of the umbilical arteries of critically ill babies for drawing blood for

testing An examination (exam or evaluation) or test is an educational assessment intended to measure a test-taker's knowledge, skill, aptitude, physical fitness, or classification in many other topics (e.g., beliefs). A test may be administered verba ...

. This is a common procedure in neonatal intensive care, and can often be performed until 2 weeks after birth (when the arteries start to decay too much). The umbilical arteries are typically not suitable for infusions.

Additional images

File:Gray31.png, Model of human embryo, 1.3 mm. long. File:Gray1111.png, Transverse section of human embryo, eight and a half to nine weeks old. File:Gray1115.png, Tail end of human embryo, twenty-five to twenty-nine days old. File:Inguinal fossae.PNG, Inguinal fossae File:Slide4khi.JPG, Umbilical artery. Deep dissection. Anterior view. File:Slide4BLA.JPG, Umbilical artery. Deep dissection. Serial cross-section.

References

External links

* - "The Female Pelvis: Branches of Internal Iliac Artery" {{DEFAULTSORT:Umbilical Artery Arteries of the abdomen Embryology of cardiovascular system