vertebral arch

Examples of vertebral arch in the following topics:

• Parts of a Vertebra

  • A vertebra consists of two parts: an anterior segment, or the vertebral body; and a posterior part, or the vertebral (neural) arch.
  • The posterior vertebral or neural arch that encloses the spinal cord.
  • The intervertebral discs that act as ligaments between the vertebral bodies.
  • The vertebral arch is formed from two, short, thick processes called pediments that extend posteriorly from the lateral sides of the vertebral body, before joining together at the midline with the laminae.
  • A single spinous process projects backwards and downwards from the center of the vertebral arch and it serves as a major attachment point for muscles and ligaments of the back.

• The Spine

  • Kyphosis is an exaggerated concave (kyphotic) curvature of the thoracic vertebral column; it is commonly known as "humpback."
  • A typical vertebra consists of the vertebral body and vertebral arch.
  • These parts together enclose the vertebral foramen that contains the spinal cord.
  • The vertebral arch is formed by a pair of pedicles and a pair of laminae.
  • Two transverse processes and one spinous process are posterior to (behind) the vertebral body.

• Overview of the Spinal Cord

  • The spinal cord runs along the inside of the vertebral column and serves as the signaling conduit between the brain and the periphery.
  • The birth defect spina bifida is a failure of the vertebral arch to close, exposing the spinal cord.
  • The spinal cord, protected by the vertebral column, begins at the occipital bone and extends down to the space between the first and second lumbar vertebrae.
  • The cauda equina ("horse's tail") is the name for the collection of nerves in the vertebral column that extends beyond the cord.
  • Relationship between the spinal cord and vertebral column, delineating the cervical, thoracic, and lumbar sections.

• Characteristics of Chordata

  • In vertebrates, the notochord is present during embryonic development, at which time it induces the development of the neural tube which serves as a support for the developing embryonic body.
  • The notochord, however, is replaced by the vertebral column (spine) in most adult vertebrates.
  • In vertebrate fishes, the pharyngeal slits develop into gill arches, the bony or cartilaginous gill supports.
  • In some terrestrial vertebrates, the tail also helps with balance, courting, and signaling when danger is near.

• Human Axial Skeleton

  • The axial skeleton forms the central axis of the human body and consists of the skull, vertebral column, and thoracic cage.
  • The adult vertebral column is comprised of 26 bones: the 24 vertebrae, the sacrum, and the coccyx bones.
  • Each vertebral body has a large hole in the center through which the nerves of the spinal cord pass.
  • The arched curvature of the vertebral column increases its strength and flexibility, allowing it to absorb shocks like a spring.
  • The axial skeleton consists of the bones of the skull, ossicles of the middle ear, hyoid bone, vertebral column, and rib cage.

• Thoracic Aorta

  • The thoracic aorta forms part of the descending aorta and is continuous with the aortic arch at its origin before becoming the abdominal aorta.
  • Contained within the posterior mediastinal cavity, it begins at the lower border of the fourth thoracic vertebra where it is continuous with the aortic arch, and ends in front of the lower border of the twelfth thoracic vertebra at the aortic hiatus in the diaphragm.
  • At its commencement, the thoracic aorta is situated on the left of the vertebral column; it approaches the median line as it descends, and at its termination lies directly in front of the column.
  • The thoracic aorta's relation, from above downward, is as follows: anteriorly with the root of the left lung, the pericardium, the esophagus and the diaphragm; posteriorly with the vertebral column; on the right side with the hemiazygos veins and thoracic duct; and on the left side with the left pleura and lung.

• Arches, Vaults, and Domes

  • This is sometimes referred to as arch action.
  • As the forces in the arch are carried to the ground, the arch will push outward at the base; this is called thrust.
  • Circular arches, also referred to as rounded arches, were commonly employed by the builders of ancient, heavy masonry arches.
  • The advantage of using a pointed arch rather than a circular arch is that the arch action in a pointed arch produces less thrust at the base.
  • Of any arch type, the parabolic arch produces the most thrust at the base, but can span the largest areas.

• Arch of the Aorta

  • The arch of the aorta follows the ascending aorta and begins at the level of the second sternocostal articulation of the right side.
  • The arch of the aorta, or the transverse aortic arch, is continuous with the upper border of the ascending aorta and begins at the level of the upper border of the second sternocostal articulation of the right side.
  • Three vessels come out of the aortic arch: the brachiocephalic artery, the left common carotid artery, and the left subclavian artery.
  • In approximately 20% of individuals, the left common carotid artery arises from the brachiocephalic artery rather than the aortic arch, and in approximately 7% of individuals the left subclavian artery also arises here.
  • This diagram shows the arch of the aorta and its branches.

• Anastomoses

  • Arterio-arterial anastomoses include actual joins (e.g. palmar arch, plantar arch) and potential ones, which may only function if the  normal vessel is damaged or blocked (e.g. coronary arteries and cortical branch of cerebral arteries).
  • Blood flows up to the brain through the vertebral arteries and through the internal carotid arteries.

• Arches and Domes

  • As the forces in an arch are carried toward the ground, the arch will push outward at the base (called thrust).
  • As the height of the arch decreases, the outward thrust increases.
  • The most common true arch configurations are the fixed arch, the two-hinged arch and the three-hinged arch.
  • The two-hinged arch is most often used to bridge long spans.
  • This type of arch has pinned connections at the base.