What is a posterior arch?

What is a posterior arch?

Description. The posterior arch forms about two-fifths of the circumference of the ring: it ends behind in the posterior tubercle, which is the rudiment of a spinous process and gives origin to the Recti capitis posteriores minores.

What is a posterior fusion defect?

Posterior vertebral fusion anomalies are relatively common and should not be mistaken for fractures. They are thought to be both developmental and pathological (e.g. spondylolysis) but are typically asymptomatic and incidental, and considered as anatomical variants.

What is Atlas hypoplasia?

Congenital hypoplasia of the posterior arch of the atlas (C1), a developmental failure of chondrogenesis, is a rare anomaly and may range from partial clefts to total agenesis of the posterior arch. Ossification of the posterior arch usually occurs between the 3rd and 5th years of life.

What is anterior arch of Atlas?

The anterior arch forms about one-fifth of the ring: its anterior surface is convex, and presents at its center the anterior tubercle for the attachment of the Longus colli muscles; posteriorly it is concave, and marked by a smooth, oval or circular facet (fovea dentis), for articulation with the odontoid process (dens …

What forms the vertebral arch?

The vertebral arch is formed by pedicles and laminae. Two pedicles extend from the sides of the vertebral body to join the body to the arch. The pedicles are short thick processes that extend, one from each side, posteriorly, from the junctions of the posteriolateral surfaces of the centrum, on its upper surface.

What is posterior longitudinal ligament?

The posterior longitudinal ligament (PLL) is a long and important ligament located immediately posterior to the vertebral bodies (to which it attaches loosely) and intervertebral discs (to which it is firmly attached). It extends from the back of the sacrum inferiorly and gradually broadens as it ascends.

When do posterior elements fuse?

Normal vertebrae form by coalescence of primary ossification centers in the prenatal period, and then by fusion of the posterior neural arch with the vertebral body in the first 3 to 6 years of life.

What is a pars defect in the spine?

A pars defect or spondylolysis is a stress fracture of the bones of the lower spine. These fractures typically occur due to overuse. They can be on one or both sides of the vertebrae. It is a common cause of low back pain in children and adolescents.

Is Klippel Feil syndrome hereditary?

In most cases, Klippel Feil syndrome (KFS) is not inherited in families and the cause is unknown. In some families, KFS is due to a genetic alteration in the GDF6, GDF3 or MEOX1 gene and can be inherited. When KFS is caused by mutations in the GDF6 or GDF3 genes, it is inherited in an autosomal dominant manner.

How can you distinguish the posterior arch from the anterior arch on an atlas?

The anterior arch forms about one-fifth of the ring: its anterior surface is convex, and presents at its center the anterior tubercle for the attachment of the Longus colli muscles and the anterior longitudinal ligament; posteriorly it is concave, and marked by a smooth, oval or circular facet (fovea dentis), for …

What is the function of the vertebral arch?

The body serves for weight bearing. The vertebral arch surrounds and protects the spinal cord. The vertebral arch is formed by the pedicles, which are attached to the posterior side of the vertebral body, and the lamina, which come together to form the top of the arch.

What is the primary function of the posterior longitudinal ligament?

The posterior longitudinal ligament runs in the spinal canal attaching to the vertebral bodies and vertebral discs and tightens with cervical flexion.

What movement does the posterior longitudinal ligament limit?

Flexion
The Anterior Longitudinal Ligament attaches to the front (anterior) of each vertebra….Primary Spinal Ligaments Include:

What age does the spine ossify?

The primary ossification centers first appear at the cervicothoracic junction at 9 weeks in utero and are followed by upper cervical then thoracolumbar vertebrae with the primary ossification centers of the lumbar neural arches the last to appear at approximately 14 weeks in utero 3.

When do spinous processes fuse?

25 years old
Several secondary centers of ossification develop around 16 years old and fuse by 25 years old. Typically, there are five secondary ossification centers, located at the tip of the spinous process, the tips of the transverse processes, and the upper and lower margins of the vertebral body (ring apophyses).