saccus Latin, a bag made of rough cloth < sakkos Greek, a garment made of coarse hair, a bag made of sackcloth < saq Biblical Hebrew, the hair-shirt of penance, a bag < chaqqu Assyrian, rough shirt < shagadu Sumerian, an under-garment.

Thus sac is possibly the oldest word used in medical English, with a long history stretching back as an almost intact lexical unit more than 8,000 years.

Sac has derivatives and diminutives borrowed into English from French, e.g., sachet and satchel, both from saccellus 'little bag.'

To sack a village by plundering it derives from medieval Latin saccare 'to pillage a place by putting the booty in rough bags and making off with it.'

In anatomy, a sac is a pouch or bag-like part of a structure or organ. The pericardium surrounds the heart as a tough, bag-like membrane sometimes called the pericardial sac or the heart sac.

The human embryo floats inside two sacs for protection and support during its development. The outer one is the chorion or chorionic sac. In the color photograph below some of the chorion has been removed to show the inner sac or amnion where the fetus floats protected in amniotic fluid and attached to its organ of nourishment, the placenta that arises in the chorion. The placenta is part of fetal tissue not maternal tissue. For the growing fetus the placenta is an organ of respiration, nourishment,and excretion. By convention the unborn human is an embryo for its first two months of existence, and afterward is a fetus during the remainder of the pregnancy.

The amniotic sac is a thin membrane filled with serous fluid enclosing the embryo.

The air passageway into the lungs terminates at the alveolar sacs. Each pouchlike alveolar sac, also called an air sac, is connected by a small duct to a bronchiole. Sometimes the diminutive form is used and these little pocket-like structures are labeled air saccules (sacculus 'little bag').

When an artery weakens and a localized part of its arterial wall protrudes and when this ballooning outward resembles a little bag on the arterial wall, the abnormality may be called a saccular aneurysm.

ANEURYSM

an-eurysm = ana Greek, through + eurysma Greek, a widening < eurys wide + isma -ism, which in medical nomenclature often denotes an abnormal condition

An aneurysm is a bulging out in the wall of an artery. The weak spot in the arterial wall is often the result of atherosclerosis in which fatty plaques form in the linings of the artery and so weaken it. High blood pressure, bacterial infection, trauma, and genetic predisposition are other causes. Common sites are the lower aorta and the arteries at the base of the brain. Drugs provide certain symptomatic relief but surgical resection of the artery is sometimes called for.

 

NEXT MEDICAL WORD

PREVIOUS MEDICAL WORD

INDEX OF MEDICAL WORDS

SELECT SAMPLES FROM OTHER WORD BOOKS

HOME