Trabecula

A trabecula (plural trabeculae. From Latin for small beam.) is 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.

On histological section, a trabecula can look like a septum, but in three dimensions they are topologically distinct, with trabeculae being roughly rod or pillar-shaped and septa being sheet-like.

Trabeculae are usually composed of dense fibrous tissue, i.e. 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.

When crossing fluid-filled spaces, trabeculae may have the function of resisting tension (as in the penis) or providing a cell filter (as in the eye.)

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.

Examples of trabeculae

 * trabeculae of bone
 * trabeculae of corpora cavernosa of penis
 * trabeculae of corpus spongiosum of penis
 * trabecular meshwork of the eye
 * trabeculae of spleen
 * trabeculae carneae
 * septomarginal trabecula

Etymology
Diminutive form of Latin trabs, which means a 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, but this can be considered poor usage on the grounds of both etymology and descriptive accuracy.