Trabecula
From Biocrawler, the free encyclopedia.
Definition and etymology
n. plural: trabeculae. adj. trabecular.
A small, often microscopic, tissue element in the form of a small beam, strut or rod, generally having a mechanical function, and usually but not necessarily composed of dense collagenous tissue.
Diminutive of Latin trabs = a small beam or bar. In the 19th century, the neologism trabeculum (with an assumed plural of trabecula) became popular, but is less etymologically correct. Trabeculum persists in some countries as a synonym for the trabecular meshwork of the eye, which is poor usage on the grounds of both etymology and descriptive accuracy.
Biology
Trabeculae are usually composed of dense fibrous tissue, ie, mainly of collagen, and in most cases provide mechanical strengthening or stiffening to a soft solid organ, such as the spleen. They can be composed of other materials, such as bone or muscle. Millions of bony trabeculae combined into a 3-dimensional lattice are seen in cancellous bone, which is light but strong. The inner surface of the ventricles of the heart shows smooth thick arches of functioning heart muscle, the 'trabeculae carnae'. When crossing fluid-filled spaces, trabeculae may have the function of resisting tension (as in inflatable organs like the penis), or providing a cell filter (as in the trabecular meshwork of the eye). On histological section, a trabecula can look like a septum, but in 3 dimensions they are topologically distinct, with trabeculae being roughly rod or pillar-shaped and septa being sheet-like. Multiple perforations in a septum may reduce it to a collection of trabeculae, as happens to the walls of some of the pulmonary alveoli in emphysema.
