Lumbar Vertebrae (Lumbar Spine)

Table of Contents:

 
Home Spine (Vertebral Column) Lumbar Vertebrae (Lumbar Spine)

Published on May 24th 2022 by

What is Lumbar Vertebrae

The lumbar vertebrae consist of five individual cylindrical bones that form the spine in the lower back. These vertebrae carry all of the upper body’s weight while providing flexibility and movement to the trunk region. They also protect the delicate spinal cord and nerves within their vertebral canal.

Where is the Lumbar Vertebrae Located

Found along the body’s midline in the lumbar (lower back) region, the lumbar vertebrae make up the region of the spine inferior to the thoracic vertebrae in the thorax and superior to the sacrum and coccyx in the pelvis.

Quick Facts

Type         Irregular bones
Length and WidthIn males: Approximately 71 cm In females: Approximately 61 cm
How many are there in the human body 1
Articulates with Occipital bone

Functions

Lumbar vertebrae provide stability for your back and spinal column and allow for a point of attachment for many muscles and ligaments.

Anatomy: Parts and Structure of Lumbar Vertebrae

There are 5 lumbar vertebrae (denoted as L1-L5) found in adult humans, and they are situated beneath the thoracic vertebrae, They are the largest, in terms of size, out of all the vertebrae because the lumbar vertebrae must be able to support the weight of the body when a person is standing due to the effects of gravity.

Lumbar Vertebrae

To summarize, the main anatomical components of a lumbar vertebra are:

  • Vertebral body
  • Vertebral arch
  • Spinous process
  • Pedicles and laminae
  • Vertebral foramen
  • Superior and inferior articular processes/facets
  • Transverse processes

Distinguishing features of the lumbar vertebrae include a thick and stout vertebral body, a blunt, quadrilateral spinous process for the attachment of strong lumbar muscles, and articular processes that are oriented differently than those found on the other vertebrae. The vertebral body is large, wider laterally compared to longitudinally, and thicker in the front than in the back. It is also flattened or slightly concave superiorly and inferiorly, concave behind, and deeply restricted at the front and laterally.

Each lumbar vertebra has a vertebral body and a vertebral arch. The vertebral arch consists of a pair of pedicles and a pair of laminae, which encircles the vertebral foramen that ultimately supports 7 processes. The pedicles are very strong and are directed backwards from the upper part of the vertebral body. As a result, the inferior vertebral notches have considerable depth. The pedicles also change in morphology from L1 to L5, increasing in width from 9 mm up to 18 mm at L5. The angle in the axial plane also increases from 10 to 20 degrees from L1 to L5.

The laminae are strong, broad, and short in morphology, and form the posterior portion of the vertebral arch. The upper lumbar laminae regions are taller instead of wider, whereas the lower lumbar laminae regions are wider instead of tall. Laminae connect the spinous process to the pedicles.

The vertebral foramen is triangular-shaped within the arch, and larger in size than in the thoracic vertebrae, but smaller than in the cervical vertebrae. The superior and inferior articular processes are well-defined, and project upward and downward from the junctions of pedicles and laminae, respectively. The superior processes are concave and face medially (like when the palms of the hands are facing each other when about to clap), whereas the inferior processes are convex and face lateralward towards the superior processes of the next vertebra. This anatomical conformation allows for resistance against the twisting of the lower spine.

Transverse processes are long and slender, with changing morphology from L1 to L5. These processes are horizontal in L1-L3, and incline a little upward in L4-L5. In L1-L3, the transverse processes arise from the junctions of the pedicles and laminae, but in L4-L5, they arise from the pedicles and posterior portions of the vertebral bodies since they are set farther forward. The transverse processes are positioned in front of the articular processes instead of behind them as in the thoracic vertebrae, and are homologous with the ribs.

Articulations

  1. Intervertebral symphyses: Adjacent vertebral bodies are joined by symphyses called intervertebral symphyses (discs). The exceptions are C1-C2 and after S2, where such symphyses do not exist.
  2. Zygapophyseal joints: Adjacent vertebral arches are connected by synovial joints called zygapophyseal (facet) joints. They are formed between superior and inferior articular facets.
  3. Atlanto-occipital joints: These joints are formed between the lateral masses of the atlas (C1) and the occipital condyles of the cranium

Ossification

All vertebrae begin ossification in the embryonic period of development around 8 weeks of gestation. They ossify from three primary ossification centers: one in the endochondral centrum (which will develop into the vertebral body) and one in each neural process (which will develop into the pedicles).

Muscule and Ligament Attachments

Muscle attachments:

  1. Lumbar muscles
  2. Thoracic muscles
  3. Back muscles

Ligament attachments:

  1. Ligamenta flava
  2. Interspinous ligaments
  3. Nuchal ligament
  4. Supraspinous ligament

References

    1. The Lumbar Spine — Teachmeanatomy.info
    2. Lumbar Vertebrae — Physio-pedia.com
    3. Anatomy, Back, Lumbar Vertebrae — Pubmed.ncbi.nlm.nih.gov
    4. Lumbar Vertebrae — Sciencedirect.com
    5. Lumbar Vertebrae — Innerbody.com

Leave a Reply

Your email address will not be published.