The vertebral column forms the central flexible pillar of the axial skeleton, protecting the delicate spinal cord while supporting the weight of the head and trunk. In the developing fetus, the spine consists of thirty-three distinct bones, but as a person matures, several bones fuse together.
Midwives frequently assess these regions during antenatal care, as increased lumbar lordosis during pregnancy often leads to lower back strain.
Despite regional variations, most vertebrae share a common architectural plan designed for protection, muscle attachment, and articulation. The anterior portion is a rounded vertebral body, which acts as the main weight-bearing pillar. Projecting posteriorly from the body are two short stalks called pedicles, which join with flattened plates known as laminae to enclose the vertebral foramen. When stacked together, these foramina form the continuous vertebral canal housing the spinal cord.
Several bony projections extend from this central ring for leverage. A single spinous process points backward and downward, easily felt just beneath the skin along the back. Two transverse processes project laterally on either side. Additionally, superior and inferior articular processes bear smooth surfaces called facets, which form moveable joints with the vertebrae immediately above and below.
A healthy adult spine is not completely straight when viewed from the side; instead, it features four distinct alternating curves. These curves act like a coiled spring, absorbing shocks from walking, running, and jumping far better than a straight rod could.
Primary curves accommodate internal organs, while secondary curves shift the body's center of gravity directly over the lower limbs for balanced upright posture.
Between adjacent vertebrae from the axis down to the sacrum sit intervertebral discs, tough fibrocartilaginous pads that account for roughly one-quarter of the spine's total length. Each disc features a tough outer ring of collagen called the annulus fibrosus and a soft, gelatinous center known as the nucleus pulposus. The nucleus acts as a shock absorber, distributing pressure evenly in all directions when the spine moves.
Between the articular processes of neighboring vertebrae are small synovial joints called zygapophyseal or facet joints. These joints glide against one another, guiding the overall range of flexion, extension, and rotation available in each region of the spine.
Because the spine must remain stable while allowing motion, powerful bands of fibrous tissue run its entire length. The anterior longitudinal ligament is a broad, strong band running down the front of the vertebral bodies, preventing hyperextension of the back. Conversely, the posterior longitudinal ligament runs inside the vertebral canal along the back of the bodies, resisting hyperflexion.
Several smaller ligaments connect adjacent arches and processes:
Midwives and nurses must evaluate spinal alignment regularly, particularly during pregnancy and postpartum care. Hormones such as relaxin increase joint laxity, which can alter posture and place unusual strain on back muscles. When inspecting a patient's back from the back and side, clinicians look for abnormal curvatures:
Early identification of postural changes allows midwives to recommend proper body mechanics, pelvic tilt exercises, and supportive garments to alleviate discomfort.