Anatomy of Lumbar Vertebrae
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Questions and Answers

What is the characteristic of the body of a typical lumbar vertebra?

  • It is square in shape
  • It has a smaller transverse diameter than anterior diameter
  • It has a transverse diameter that is greater than the anterior diameter (correct)
  • It is narrower in the upper region and wider in the lower region

    • What is the orientation of the superior articular facets in the upper lumbar region?

  • They face anteriorly and laterally
  • They face posteriorly and medially
  • They face vertical and convex
  • They face medial to posterior-medial (correct)

    • What is the function of the mamillary processes?

  • They serve as attachment points for the multifidus and medial intertransverse muscles (correct)
  • They serve as bony landmarks for the spine
  • They serve as weight-bearing surfaces
  • They serve as attachment points for the rotatores muscles

    • What is the shape of the vertebral canal in the lumbar region?

    <p>Triangular</p> Signup and view all the answers

    What is the direction that the pedicles project?

    <p>Posterolaterally</p> Signup and view all the answers

    What is the shape of the laminae in the lumbar region?

    <p>Short and broad</p> Signup and view all the answers

    What is the orientation of the inferior articular facets in the lumbar region?

    <p>Vertical and convex</p> Signup and view all the answers

    What is the primary function of the lumbar vertebrae?

    <p>To support great compressive loads</p> Signup and view all the answers

    What is the shape of the vertebral foramen?

    <p>Triangular</p> Signup and view all the answers

    What is the characteristic of the transverse process in the lumbar region?

    <p>It is not described in the text</p> Signup and view all the answers

    What is the function of the accessory processes?

    <p>To serve as attachment sites for the multifidus and medial intertransverse muscles</p> Signup and view all the answers

    What is the orientation of the apophyseal joints in L5–S1?

    <p>Closer to the frontal plane</p> Signup and view all the answers

    What is the shape of the spinous process?

    <p>Broad and thick</p> Signup and view all the answers

    What is the characteristic of the 5th lumbar vertebra?

    <p>It has a wedge-shaped body</p> Signup and view all the answers

    What is the function of the L5–S1 apophyseal joints?

    <p>To provide anterior-posterior stability to the lumbosacral junction</p> Signup and view all the answers

    What is the characteristic of the L5/S1 lumbosacral disk?

    <p>It is wedge-shaped</p> Signup and view all the answers

    What is the direction of the transverse process?

    <p>Horizontally</p> Signup and view all the answers

    What is the component of the lumbosacral joint?

    <p>Anterior intervertebral joint and posterior apophyseal joint</p> Signup and view all the answers

    What type of joints are formed between the articular processes of L5 and S1 vertebrae?

    <p>Zygapophysial joints</p> Signup and view all the answers

    Which direction are the facets of S1 positioned?

    <p>Posteromedially</p> Signup and view all the answers

    What movement is NOT allowed in the lumbosacral joint?

    <p>Rotation</p> Signup and view all the answers

    What is the result of an increase in the lumbosacral angle?

    <p>Increase in lordosis of the lumbar curve</p> Signup and view all the answers

    What is the term for the angle formed by the first sacral segment with the horizontal?

    <p>Lumbosacral angle</p> Signup and view all the answers

    What is the effect of an increase in the lumbosacral angle on the lumbosacral joint?

    <p>Increase in shearing stress</p> Signup and view all the answers

    Which vertebrae form the lumbosacral articulation?

    <p>L5 and S1</p> Signup and view all the answers

    What is the primary function of the facets of S1?

    <p>To prevent dislocation of the lumbar vertebra</p> Signup and view all the answers

    What is the position of the inferior facet of the articular processes of L5 vertebrae?

    <p>Anterolaterally</p> Signup and view all the answers

    Study Notes

    Typical Lumbar Vertebrae

    • The body of a typical lumbar vertebra is massive, with a transverse diameter greater than its anterior diameter and height.
    • The size and shape of the vertebra reflect the need to support great compressive loads caused by body weight, ground reaction forces, and muscle contraction.
    • Laminae and pedicles are short and thick, forming the posterior and lateral walls of the nearly triangular vertebral canal.
    • Pedicles are short and thick, projecting posterolaterally.
    • Laminae are short and broad.
    • Superior articular facets are moderately concave, facing medial to posterior-medial.
    • Inferior articular facets are vertical and convex, facing slightly anteriorly and laterally.
    • Mamillary processes, small bumps, are located on the posterior edge of each superior articular facet and serve as attachment for the multifidus and medial intertransverse muscles.
    • Transverse process is long and slender, extending horizontally.
    • Accessory processes, small and irregular bony prominences, are located on the posterior surface of the transverse process near its attachment to the pedicle, and serve as attachment sites for the multifidus and medial intertransverse muscles.
    • Spinous process is broad and thick, extending horizontally.
    • Vertebral foramen is triangular and larger than the thoracic vertebral foramen but smaller than the cervical vertebral foramen.

    5th Lumbar Vertebra (L5)

    • The fifth lumbar vertebra is a transitional vertebra, differing from the rest of the lumbar vertebrae in that it has a wedge-shaped body.
    • The anterior portion of the body is of greater height than the posterior portion.
    • The L5/S1 lumbosacral disk is also wedge-shaped.
    • The inferior articular facets of L5 articulate with the superior articular facets of the sacrum.
    • Apophyseal joints are typically oriented much closer to the frontal plane than the other lumbar articulations.

    Lumbosacral Joint

    • The lumbosacral joint is formed by two separate articulations: the anterior intervertebral joint and the facet joints.
    • The anterior intervertebral joint is formed between the vertebral bodies of L5 and S1, separated by a large intervertebral disc and connected by vertebral ligaments.
    • The facet joints are two zygapophysial joints formed between the articular processes of L5 and S1 vertebrae.
    • The facets of S1 are positioned posteromedially and interlock with the anterolaterally placed inferior facet of the articular processes of L5 vertebrae, preventing the dislocation of the lumbar vertebra along the incline of the sacrum.
    • The lumbosacral joint is the site of most movements of the lumbar spine, including flexion, extension, and a minimal degree of lateral flexion.

    Lumbosacral Angle (Lumbo)sacral Angle or Sacral Angle

    • The first sacral segment, which is inclined slightly anteriorly and inferiorly, forms an angle with the horizontal called the lumbosacral angle.
    • The size of the angle varies with the position of the pelvis and affects the superimposed lumbar curvature.
    • An increase in this angle will result in an increase in lordosis of the lumbar curve and will increase the amount of shearing stress at the lumbosacral joint.

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    Description

    Learn about the structure and features of lumbar vertebrae, including transverse process, accessory processes, spinous process, and vertebral foramen.

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