ANATOMY ( VERTEBRAE COLUMN)

• The back consists of the posterior aspect of the body and provides the musculoskeletal axis of support for the trunk
• The back contains the spinal cord and proximal parts of the spinal nerves, which send and receive information to and from most of the body
• Skeletal components of the back mainly consist of the vertebrae and associated intervertebral discs
• The skull, scapulae, pelvic bones (ileum, ischium, pubis), and ribs also contribute to the bony framework of the back and provide sites for muscle attachment
• There are approximately 33 vertebrae, subdivided into five groups based on morphology and location
• Seven cervical vertebrae are characterized by small size, bifid spinous processes, and the presence of a foramen in each transverse process
• Twelve thoracic vertebrae are characterized by articulated ribs
• Five lumbar vertebrae are characterized by their large size and form the skeletal support for the posterior abdominal wall
• Five sacral vertebrae fuse into one single bone called the sacrum, which articulates with a pelvic bone and is a component of the pelvic wall
• A variable number, usually four, of coccygeal vertebrae fuse into a single small triangular bone called the coccyx
• A typical vertebra consists of a vertebral body and a posterior vertebral arch
• The vertebral body is the weight-bearing part of the vertebra and is linked to adjacent vertebral bodies by intervertebral discs and ligaments
• The vertebral arch consists of pedicles and laminae
• A spinous process projects posteriorly and inferiorly from the junction of the two laminae and is a site for muscle and ligament attachment
• A transverse process extends posterolaterally from the junction of the pedicle and lamina on each side and is a site for muscle and ligament attachment and articulation with ribs in the thoracic region
• The vertebral arch forms the lateral and posterior parts of the vertebral foramen
• The vertebral foramina of all the vertebrae together form the vertebral canal, which contains and protects the spinal cord
• The vertebral arch of each vertebra consists of pedicles and laminae
• Superior and inferior articular processes articulate with adjacent vertebrae
• Superior and inferior vertebral notches participate in forming intervertebral foramina
• The atlas and axis are specialized cervical vertebrae that accommodate movement of the head
• The atlas lacks a vertebral body and is ring-shaped, articulating with the occipital condyle of the skull and the superior articular process of the axis
• The axis has a large tooth-like dens that extends superiorly from the vertebral body and articulates with the anterior arch of the atlas
• The atlanto-occipital joint allows the head to nod up and down on the vertebral column
• The dens acts as a pivot that allows the atlas and attached head to rotate on the axis, side to side
• The thoracic vertebrae are characterized by their articulation with ribs
• A typical thoracic vertebra has two partial facets on each side of the vertebral body for articulation with the head of its own rib and the rib below
• Each transverse process has a facet for articulation with the tubercle of its own rib
• The lumbar vertebrae are distinguished by their large size and lack of facets for articulation with ribs
• The transverse processes are thin and long, except for vertebra LV, which has massive cone-shaped processes for iliolumbar ligament attachment
• The vertebral body of a typical lumbar vertebra is cylindrical and the vertebral foramen is triangular and larger than in thoracic vertebrae
• The sacrum is a single bone representing the fused sacral vertebrae
• It articulates above with vertebra LV and below with the coccyx, and has large L-shaped facets for articulation with pelvic bones
• The sacrum has posterior and anterior sacral foramina for the passage of spinal nerves
• The coccyx articulates with the inferior end of the sacrum and represents fused coccygeal vertebrae
• It is characterized by its small size and the absence of vertebral arches and a vertebral canal
• Intervertebral foramina allow structures like spinal nerves and blood vessels to pass in and out of the vertebral canal
• Each intervertebral foramen is bordered posteriorly by the zygapophysial joint and anteriorly by the intervertebral disc and adjacent vertebral bodies
• Pathology in these structures can affect structures within the foramen
• Vertebral column curvatures:

  • Primary curvature is concave anteriorly in thoracic and sacral regions
  • Secondary curvatures are concave posteriorly in cervical and lumbar regions
  • Secondary curvatures bring the center of gravity into a vertical line, balancing the body's weight efficiently