Trabeculae is the plural form of trabecula, which means "small beam" or "small wood plank" in Latin to describe a certain tissue structure. The term is meant to be the smaller form of the Latin word trabes, thus denoting its most common function — support. Trabeculae, also described as rods or struts, can be found in certain areas of the body, which include the bones, the penis, the heart and the eyes. They also vary in manufacture and function depending on location.
Perhaps the most commonly known form of these struts is found in the bones, where it functions as the main anatomical and mechanical unit of a cancellous bone. This type of tissue is instrumental in forming bone, as the beams create the tissue with a network of interconnecting spike-like structures. The small beams are most prominent in bones like the skull and the femur, or thigh bone.
Other types act as filters, with the best example being the trabecular meshwork of the eye. Covering part of the base of the cornea that is near the eye's ciliary body, the trabecular meshwork drains the thick watery substance between the cornea and the lens called aqueous humour. It does so through the anterior chamber, which is the fluid-filled space that houses the aqueous humour. Thus, the trabecular meshwork contributes to the regulation of intraocular pressure — the pressure inside the eye — and consequently assists in preventing medical conditions, such as glaucoma.
Trabeculae are also instrumental in providing resistance to tension in fluid-filled areas of the body. This is important for certain body parts like the penis, which contains erectile tissue. The internal surfaces of the corpus spongiosum and the corpus cavernosa — the spongy regions that expand with blood during an erection — are made up of these fibrous tissues, which help support the organ.
Other types include trabeculae carneae — or columnae carneae, septomarginal trabecula, and trabeculae of spleen, with the first two found in the heart. Described as muscular columns that extend from the heart's left and right ventricles, the columnae carneae aid in the ability of the heart to have an efficient pump rate. The septomarginal trabecula, found in the right ventricle, contributes to the coordinated contraction of the anterior papillary muscle in this particular chamber of the heart. The trabeculae of spleen is aptly named, since it is located in the spleen. Here, the appearance of the partitions is that of branches, thus constituting the main feature of the organ.
