A trabecula is a small, often microscopic, tissue

Biological tissue

Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...

 element in the form of a small beam

Beam (structure)

A beam is a horizontal structural element that is capable of withstanding load primarily by resisting bending. The bending force induced into the material of the beam as a result of the external loads, own weight, span and external reactions to these loads is called a bending moment.- Overview...

, strut

Strut

A strut is a structural component designed to resist longitudinal compression. Struts provide outwards-facing support in their lengthwise direction, which can be used to keep two other components separate, performing the opposite function of a tie...

 or rod

Rod (geometry)

In geometry, a rod is a three-dimensional, solid cylinder....

, generally having a mechanical function, and usually composed of dense collagen

Collagen

Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...

ous tissue (such as the trabecula

Trabeculae of spleen

The fibroelastic coat of the spleen invests the organ, and at the hilum is reflected inward upon the vessels in the form of sheaths. From these sheaths, as well as from the inner surface of the fibroelastic coat, numerous small fibrous bands, the trabeculae of the spleen , emerge from all...

 of the spleen

Spleen

The spleen is an organ found in virtually all vertebrate animals with important roles in regard to red blood cells and the immune system. In humans, it is located in the left upper quadrant of the abdomen. It removes old red blood cells and holds a reserve of blood in case of hemorrhagic shock...

.) They can be composed of other materials; in the heart

Heart

The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...

, for example, muscle

Muscle

Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

s such as trabeculae carneae

Trabeculae carneae

The trabeculae carneae , are rounded or irregular muscular columns which project from the inner surface of the right and left ventricles of the heart...

 and septomarginal trabecula

Septomarginal trabecula

The septomarginal trabecula is a muscular band of heart tissue found in the right ventricle. It is well-marked in sheep and some other animals, and frequently extends from the base of the anterior papillary muscle to the ventricular septum.This septomarginal trabecula is important because it...

 form similar structures. The formation of trabecula is known as trabeculation.

On histological section

Histological section

Histological section refers to thin slices of tissue applied to a microscopic slide, usually around 5 to 10 micrometres thick, which are viewed under a microscope...

, trabecula of a cancellous bone can look like a septum

Septum

In anatomy, a septum is a wall, dividing a cavity or structure into smaller ones.-In human anatomy:...

, but in three dimensions they are topologically distinct, with trabecula being roughly rod or pillar-shaped and septa being sheet-like.

When crossing fluid-filled spaces, trabecula may have the function of resisting tension (as in the penis

Penis

The penis is a biological feature of male animals including both vertebrates and invertebrates...

, see for example trabeculae of corpora cavernosa

Trabeculae of corpora cavernosa of penis

From the internal surface of the fibrous envelope of the corpora cavernosa penis, as well as from the sides of the septum, numerous bands or cords are given off, which cross the interior of these corpora cavernosa in all directions, subdividing them into a number of separate compartments, and...

 and trabeculae of corpus spongiosum

Trabeculae of corpus spongiosum of penis

The fibrous envelope of the corpus cavernosum urethræ is thinner, whiter in color, and more elastic than that of the corpora cavernosa penis. It is called the trabeculae of corpus spongiosum of penis....

) or providing a cell filter (as in the trabecular meshwork of the eye

Human eye

The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...

.)

Multiple perforations in a septum may reduce it to a collection of trabecula, as happens to the walls of some of the pulmonary alveoli

Pulmonary alveolus

An alveolus is an anatomical structure that has the form of a hollow cavity. Found in the lung parenchyma, the pulmonary alveoli are the dead ends of the respiratory tree, which outcrop from either alveolar sacs or alveolar ducts, which are both sites of gas exchange with the blood as well...

 in emphysema

Emphysema

Emphysema is a long-term, progressive disease of the lungs that primarily causes shortness of breath. In people with emphysema, the tissues necessary to support the physical shape and function of the lungs are destroyed. It is included in a group of diseases called chronic obstructive pulmonary...

.

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

Trabecular meshwork

The trabecular meshwork is an area of tissue in the eye located around the base of the cornea, near the ciliary body, and is responsible for draining the aqueous humor from the eye via the anterior chamber .The tissue is spongy and lined by trabeculocytes; it allows fluid to drain into a set of...

 of the eye

Eye

Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...

, but this can be considered poor usage on the grounds of both etymology and descriptive accuracy.