Each vertebra except the Atlas is composed of a body and an arch; the arch is made up of two pedicles, short, thick plates of bone extending outward and backward from the postero-lateral surface of the body nearer its upper than its lower border, two laminae, thin plates of bone extending backward and inward from their union with the pedicles and joining behind to form the spinous process, and has projecting from it seven processes, two transverse, one spinous, and four articular, two of which are superior and two inferior. The foramen enclosed by the body, pedicles, and laminae is called the neural or vertebral foramen and the canal formed by the connection of these foramina and completed by the ligaments which unite the arches is called the neural, vertebral, or spinal canal. It contains the spinal cord with its membranes and the roots of the spinal nerves. By means of the four articular processes each true vertebra except the first articulates with its fellows above and below. The body of the vertebra is its largest portion and is joined to its fellows by fibrocartilaginous disks which are sufficiently elastic to permit some torsion and compression. Nine sets of ligaments, including the intervertebral substance just mentioned, bind the vertebrae firmly together. Many muscles are attached to the spinal column. The intervertebral foramina are openings at the sides of the vertebrae, formed by the notching of apposed pedicles. These openings are surrounded by bone, cartilage, and ligaments and vary in shape in different sections of the spine. They permit the exit of the spinal nerves and their sheaths, the re-entrance of some nerve fibres into the neural canal, and the passage of blood-vessels to and from the cord. The entire philosophy of Chiropractic focuses at the intervertebral foramen because there we find the primary cause of all pathological changes in the body. The spinous and transverse processes merit particular description since they are the levers by which vertebrae are adjusted and nerve impingements at the intervertebral foramina corrected. But it will be found easiest to describe these processes separately in different sections of the spine and before proceeding to this description, a brief picture of the peculiar vertebrae will be presented.