What is the embryological origin of the vertebral column?

The vertebral column develops from sclerotomes, which are ventromedial parts of somites derived from paraxial mesoderm. These cells migrate medially around the notochord and neural tube to form mesenchymal vertebral models.

How does the intersegmental pattern of vertebrae form during development?

Each vertebra is intersegmental, formed by the fusion of the caudal half of one sclerotome and the cranial half of the adjacent one. This process, called resegmentation, allows myotomes to bridge vertebrae, facilitating spinal movements.

What are the key components formed from mesenchymal condensation in vertebral development?

Condensation of mesenchyme leads to the formation of the centrum (vertebral body), neural arches (pedicles, laminae, spines, and processes), and costal processes (costal elements, which form ribs in the thoracic region).

How does ossification occur in a typical vertebra?

A typical vertebra ossifies from three primary centers: one for the centrum and one for each vertebral arch. At birth, these parts are joined by cartilage, with the neurocentral joints fusing by 3–6 years to form the complete vertebra.

What is spina bifida and what are its types?

Spina bifida is a failure of neural arch fusion, leading to dorsal vertebral gaps. Types include occulta (skin-covered defect with a hair patch), meningocele (meningeal sac with CSF herniation), meningomyelocele (meninges and spinal cord herniation), and aperta (exposed open neural tube, the most severe).

What are some congenital vertebral anomalies related to development?

Congenital anomalies include hemivertebra (failure of one ossification center, causing a wedge-shaped vertebra and congenital scoliosis), congenital fusions (such as occipitalization of atlas, sacralization of L5, or lumbarization of S1), and spondylolisthesis (pedicles fail to fuse with the body, leading to L5 slipping over the sacrum).

Vertebral Column Development – Sclerotomes & Resegmentation