Question: A trabecula is a tissue element in the form of a structural element whose mode of deflection is primarily by what?

Context paragraphs:
Beam (structure): A beam is a structural element that primarily resists loads applied laterally to the beam's axis.  Its mode of deflection is primarily by bending.  The loads applied to the beam result in reaction forces at the beam's support points.  The total effect of all the forces acting on the beam is to produce shear forces and bending moments within the beam, that in turn induce internal stresses, strains and deflections of the beam.  Beams are characterized by their manner of support, profile (shape of cross-section), length, and their material.

Plate (structure): A plate is a structural element which is characterized by two key properties.  Firstly, its geometric configuration is a three-dimensional solid whose thickness is very small when compared with other dimensions.  Secondly, the effects of the loads that are expected to be applied on it only generate stresses whose resultants are, in practical terms, exclusively normal to the element's thickness.

Deflection (engineering): In engineering, deflection is the degree to which a structural element is displaced under a load.  It may refer to an angle or a distance.

Shear and moment diagram: Shear and bending moment diagrams are analytical tools used in conjunction with structural analysis to help perform structural design by determining the value of shear force and bending moment at a given point of a structural element such as a beam.  These diagrams can be used to easily determine the type, size, and material of a member in a structure so that a given set of loads can be supported without structural failure.  Another application of shear and moment diagrams is that the deflection of a beam can be easily determined using either the moment area method or the conjugate beam method.

Stress resultants: Stress resultants are simplified representations of the stress state in structural elements such as beams, plates, or shells.  The geometry of typical structural elements allows the internal stress state to be simplified because of the existence of a "thickness'" direction in which the size of the element is much smaller than in other directions.  As a consequence the three traction components that vary from point to point in a cross-section can be replaced with a set of resultant forces and resultant moments.  These are the stress resultants (also called "membrane forces", "shear forces", and "bending moment") that may be used to determine the detailed stress state in the structural element.  A three-dimensional problem can then be reduced to a one-dimensional problem (for beams) or a two-dimensional problem (for plates and shells).

Regular element of a Lie algebra: In mathematics, a regular element of a Lie algebra or Lie group is an element whose centralizer has dimension as small as possible.  In the specific case of "n"x"n" matrices over an algebraically closed field (such as the complex numbers), an element "M" is regular if and only if its Jordan normal form contains a single Jordan block for each eigenvalue.  In that case, the centralizer is the set of polynomials of degree less than "n" evaluated at the matrix "M", and therefore the centralizer has dimension "n" (but it is not necessarily an algebraic torus).

Bending moment: A bending moment is the reaction induced in a structural element when an external force or moment is applied to the element causing the element to bend.  The most common or simplest structural element subjected to bending moments is the beam.  The example shows a beam which is simply supported at both ends.  Simply supported means that each end of the beam can rotate; therefore each end support has no bending moment.  The ends can only react to the shear loads.  Other beams can have both ends fixed; therefore each end support has both bending moment and shear reaction loads.  Beams can also have one end fixed and one end simply supported.  The simplest type of beam is the cantilever, which is fixed at one end and is free at the other end (neither simple or fixed).  In reality, beam supports are usually neither absolutely fixed nor absolutely rotating freely.

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 that supports or anchors a framework of parts within a body or organ.  A trabecula generally has a mechanical function, and is usually composed of dense collagenous tissue (such as the trabecula of the spleen).  They can be composed of other materials such as muscle and bone.  In the heart, muscles form trabeculae carneae and septomarginal trabecula.  Cancellous bone is formed from groupings of trabeculated bone tissue.

Beam deflection tube: Beam deflection tubes, sometimes known as sheet beam tubes, are vacuum tubes with an electron gun, a beam intensity control grid, a screen grid, sometimes a suppressor grid, and two electrostatic deflection electrodes on opposite sides of the electron beam, that can direct the rectangular beam to either of two anodes in the same plane.  They can be used as two-quadrant, single-balanced mixers or (de)modulators with very linear qualities, their mode of operation similar to one-half of a Gilbert Cell, by applying an unbalanced signal "f" to the control grid and a balanced signal "f" to the deflection electrodes, then extracting the balanced mixing products "f" − "f" and "f" + "f" from the two anodes.  Similar to a pentagrid converter, the cathode and the first two grids can be made into an oscillator.  Two beam deflection tubes can be combined to form a double-balanced mixer.

Column: A column or pillar in architecture and structural engineering is a structural element that transmits, through compression, the weight of the structure above to other structural elements below.  In other words, a column is a compression member.  The term column applies especially to a large round support (the "shaft" of the column) with a capital and a "base" or pedestal and made of stone, or appearing to be so.  A small wooden or metal support is typically called a post, and supports with a rectangular or other non-round section are usually called piers.  For the purpose of wind or earthquake engineering, columns may be designed to resist lateral forces.  Other compression members are often termed "columns" because of the similar stress conditions.  Columns are frequently used to support beams or arches on which the upper parts of walls or ceilings rest.  In architecture, "column" refers to such a structural element that also has certain proportional and decorative features.  A column might also be a decorative element not needed for structural purposes; many columns are "engaged", that is to say form part of a wall.

Supporting paragraphs: Trabecula Beam (structure)
Answer: bending