Describe spinal processes, noting their function from COA
Seven processes arise from the vertebral arch of a typical vertebra (Fig. 4.2A-C):
a. Spinous (1) median process projects posteriorly (and usually inferiorly, typically overlapping the vertebra below) from the vertebral arch at the junction(union) of the two laminae.
b. Transverse (2) bilateral processes project posterolaterally from the junctions of the pedicles and laminae.
*The spinous and transverse processes provide attachment for deep back muscles and serve as levers, facilitating the muscles that fix or change the position of the vertebrae.
c. Articular (4) processes (G. zygapophyses)—two superior and two inferior—also arise from the junctions of the pedicles and laminae, each bearing an articular surface (facet).
*The articular processes are in apposition with corresponding processes of vertebrae adjacent (superior and inferior) to them, forming zygapophysial (facet) joints (Fig. 4.2D). Through their participation in these joints, these processes determine the types of movement permitted and restricted between the adjacent vertebrae of each region.
*The articular processes also assist in keeping adjacent vertebrae aligned, particularly preventing one vertebra from slipping anteriorly on the vertebra below. Generally, the articular processes bear weight only temporarily, as when one rises from the flexed position, and unilaterally when the cervical vertebrae are laterally flexed to their limit. However, the inferior articular processes of the L5 vertebra bear weight even in the erect posture.