Spine (Term applied to the backbone)
Collier's New Encyclopedia (1921)
the term applied to the backbone of a vertebrated animal, and so called from the thorn-like processes of the vertebræ. The human vertebral column is composed, in the child, of 33 separate pieces, but in the adult the number is only 26, several pieces having become blended together. These separate bones are arranged one on the top of the other, with a layer of gristle between each which helps to unite them, while this union is completed by partially movable joints and strong fibrous ligaments. The first 7 vertebræ, which are called cervical, occupy the region of the neck; 12 form the supports from which spring the ribs, and constitute the main portion of the back, being accordingly called dorsal; 5 in "the small of the back" are denominated lumbar; 5 pieces follow which, in the adult, unite to form the sacrum; and 4 which unite to form the coccyx. The vertebral column so arranged presents two forward curves, the first in the neck, the second at the lower part of the back; and two corresponding backward curves. The vertebræ differ in form according as they belong to the cervical, dorsal, or lumbar region, but they have all certain characteristics in common. Each possesses what is called a body, an arch which incloses a ring, and various projections and notches by means of which the bones are articulated. When the vertebræ are in position the rings are all situated one above the other, and so form a cavity or canal in which lies the protected spinal cord. The disease to which this bony structure is most liable is called angular curvature of the spine. Beginning with inflammation it goes on to ulceration (caries), till one or more of the vertebræ becomes soft and breaks down. The result of this is that the vertebræ are crushed together, the backbone bent, and a projection or hump gradually formed behind. The modern method of treatment is to apply to the patient's body, from the hips to the arm pits, a continuous bandage of plaster of Paris. Lateral curvature of the spine is not so much due to disease of the column as to relaxed condition of the body. a Strengthening food, regular, moderate exercise, and cold bathing may prove sufficient to effect a cure.
What Has Changed in the Last Century
The anatomy Collier's set out in 1921 is still what medical students learn, down to the 33 pieces in the child and 26 in the adult; only the vocabulary has shifted, with the twelve rib-bearing "dorsal" vertebrae now almost always called thoracic. The medicine has moved much further. The "angular curvature" that begins in inflammation and ends in a hump was tuberculosis of the spine (Pott's disease), and since streptomycin in 1944 and isoniazid in the 1950s it is treated with drugs rather than a plaster-of-Paris jacket from hips to armpits. Lateral curvature is no longer put down to a "relaxed condition of the body" cured by cold bathing: most cases are idiopathic scoliosis, managed with braces and, since Harrington's rod in the early 1960s, metal instrumentation; and the "layer of gristle between each" vertebra is now understood as the intervertebral disc, whose herniation was linked to sciatica by Mixter and Barr in 1934.
Written for this edition, 2026.