The so-called intervertebral disc: A 4-D reverie

Abstract

A Canadian physician had regretted that there is too vertebrate part of an elephant is not the massive skull or much of “yes, sir-ring” in medical institutions. A spoken, spine, but the head-foot called the trunk that is powerful more so a printed, word gets taken as gospel truth, an and versatile sans any bone, much like in the mollusc (= idee fixe, till ordinary logic compels you to question what soft) octopus whose ten head-feet (hence the octopus is a has been taken for granted. The intervertebral disc (IVD) cephalopod) match the vertebrate agility of the boneless is a good example semantically injusticiated and begging elephantine trunk. Vis-a-vis the human vertebral column, for a redressal in the court of intellectual appeal. it is the discs that allow all the twists and turns, the Anatomic thinking-n-teaching, epitomized by Gray’s vertebrae being incapable of the same and merely following Anatomy, is osteocentric, a clear error of putting the cart whatever the discs dictate. But for the discs, there would before the horse. For bones, in phylogeny and ontogeny, be no ease of a ballerina nor of an ice-skater, nor the grace arrive as a relaxed afterthought. The deltoid precedes the of the flamingo’s neck, nor the multiple circlings of the humerus in development, so that, if at all, it is the humerus reptiliean body. The marvel of the human and animal that should seek ‘attachment’ to the muscle. The locomotion is through the munificence of the so-called mandibular nerve does not, nor had ever to ‘pass’ through IVDs. the foramen ovale which fashions itself round the Is IVD disc at all? The lexicons define a disc as ‘a circular preformed nerve. All the IVDs are well-formed and clearly plate, round and flattened’. In man, the IVDs contribute delineated, before a spicule of bone has appeared in the to more that one-third of the column length. Then what so-called vertebrae. Moreover, each IVD represents the to talk of a giraffe (height 18-20 feet), whose neck is more centre of a somite, a fact verifiable by the emergence of than eight feet long, has only seven vertebrae and hence every pair of spinal nerves at the level of IVD. The humility has to have some discs that are as tall as four to six inches! that each IVD shows by looking a radiological vacant space The human lumbosacral vertebra is two and a half times between two osseous prominences called the vertebrae taller in front than behind and it is this height that has earned for itself the secondary status of being determines the sharp lumbosacral curve that is at the root intervertebral. The fact is that each vertebra is interdiscal. of the evolution of the erect posture. The curves of the The IVD is primary, the vertebrae playing a second fiddle human vertebral column are the courtesy of the varying to it. It may be safely generalized that, contrary to the anterior and posterior heights of the IVDs. It is a lordotic continuing osteocentric anatomy, it is the soft tissues that curve if the anterior height is greater and kyphotic if the lead and the bones follow from womb to tomb, in health and disease, in situ and after surgery. Let us resolve to exile the irritating appellation ‘intervertebral’ once and for ever. Every so-called vertebra and every single bone, is a discrete island resting in an uninterrupted ocean of soft tissues, an ordinary fact good enough to justify the second place accorded to all bones. Do the vertebrae deserve to be so called? The words vertebra-vertebrate are derived from Sanskritverten (hence pariverten) and Latin vertere meaning to turn, thus also connoting a joint. Therefore a vertebrate is one who can turn at a joint, thus making the millipede the greatest vertebrate of all. The error has been to equate static osseousness with dynamic vertebrateness. The most posterior height of the IVDs is greater. An IVD is anything but a disc for unlike a disc, it is a three-dimensional (3-D) structure. This journal has defined an IVD as a pulvinot (from pulvinus= pillow/cushion and not from notos=back). An IVD is a series of your back-cushions that are a marvel of engineering design. Each pulvinot is a sphere of strong fibrous tissue, better called spherus (and not annulus) fibrosus, containing in its center a ball of mucoid connective tissue called nucleus pulposus. The two comprise a ball-within-ball joint that works on the same principle as does a pneumatic tire. The compression exerted on the nucleus pulposus makes it stretch the spherus fibrosus, the compression/stretch forces absorbing