Editor-In-Chief: C. Michael Gibson, M.S., M.D. 
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
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.