The document provides an overview of the anatomy of the lumbosacral spine. It discusses the bones that make up the vertebral column, including the lumbar and sacral regions. It describes the functions of supporting the body, transmitting forces, and protecting the spinal cord. The document outlines the intrinsic and extrinsic muscles that move and support the vertebral column. It details the typical vertebral structure, vertebral canal, discs, facets, and ligaments that connect the vertebrae. In summary, the document provides a comprehensive anatomical description of the bones, joints, muscles and ligaments that make up the lumbosacral spine.

1. Anatomy of Lumbosacral
Spine
Dr. M. Taqi Ehsani
PGY1 of Orthopedic, FMIC

2. Overview
Bones
• 33 vertebrae
• Cervical 7
• Thoracic 12
• Lumbar 5
• Sacral 5
• Coccygeal 3-4

3. Functions
• Support:
• Skeletal and muscular elements support the
body’s weight
• transmit forces through the pelvis to the lower
limb
• carry and position the head
• brace and help maneuver the upper limb

4. Laterally, it has curvatures:
• Primary Curvature: Concave anteriorly,
Thoracic and Sacral
• Secondary Curvature: Concave
posteriorly, Cervical and Lumbar Region

5. Protection of the nervous system
The vertebral column and associated soft
tissues contain the spinal cord and
proximal parts of the spinal nerves

6. Muscles
Extrinsic
• Superficial group
(Involved with
movement upper
limbs)
• Intermediate group
(Involved with
movement thoracic
wall)
• Innervated by anterior
rami of spinal nerves

7. Intrinsic muscles:
(Deep Group)
• Deep and innervated by the
posterior rami of spinal nerves
• Support and move the vertebral
column and participate in
moving the head

8. Movement
Extrinsic muscles: move the
upper limbs and ribs
Intrinsic muscles: maintain
posture and move the vertebral
column
• Movements:
• Flexion (Anterior Bending)
• Extension
• Lateral Flexion
• Rotation

9. Typical Vertebra
Vertebral body
• Anterior, major weight
bearing component
• Increase in size from C2 to L5
Vertebral arch
• Form the lateral and
posterior walls of the
vertebral canal

10. Vertebral Canal
The spinal cord lies within a bony
canal formed by adjacent vertebrae
and soft tissue elements
• Anterior wall: formed by vertebral
bodies, intervertebral discs and
associated ligaments
• Lateral wall and roof: formed by
vertebral arches and ligaments

11. Difference of Lumber Vertebra with others
• Lack of facets for articulation
with ribs
• Thin and long transverse
processes
• Absence of the foramen
transverse
• Largest segment of vertebral
column

12. Sacrum
• Single bone that represents
the five fused sacral vertebrae
• Triangular in shape with the
apex pointed inferiorly,
concave anterior surface
• Two large L-shaped facets on
each lateral surface for
articulation with the pelvic
bones

13. Joints
Two major joints between vertebrae
are:
• Symphyses between vertebral bodies
• Synovial joints between articular
processes
A typical vertebra has a total of six joints
with adjacent vertebra: 4 synovial joints
(two above and two below), 2 symphyses
(one above and one below)

14. Symphyses between vertebral bodies
(intervertebral discs)
• Consists of an outer anulus fibrosus, an
outer ring of collagen, limits rotation
between vertebra
• Central nucleus pulposus, is gelatinous,
absorbs compression forces between
vertebra
Joints between vertebral arches
(Zygapophysial joints)
• The synovial joints between superior and
inferior articulation processes on adjacent
vertebra are the zygapophysial joints

15. Ligaments
Anterior longitudinal ligaments
• Anterior surfaces of the vertebral bodies
• Attached superiorly to base of skull and extended
inferiorly to the anterior surface of sacrum
Posterior longitudinal ligaments
• Posterior surface of vertebral bodies and lines
anterior surface of vertebral canal

16. Ligamenta flava
• On each side, pass
between the lamina of
adjacent vertebra
• Thin, broad ligaments
consist predominantly
of elastic tissue and
form part of the
posterior surface of
vertebral canal

17. Supraspinous ligaments and ligamentum
nuchae
• Connects and passes along the tips of the
vertebral spinous processes from C7 to the
sacrum
• From C7 to the skull, Ligamentum Nuchae,
supports the head, resists flexion and facilitates
returning the head to the anatomical position
• The broad lateral surface and the posterior edge
of the ligament provide attachment for adjacent
muscles

18. Interspinous ligaments
• Pass between adjacent vertebral spinous
processes, attach from base to the apex of
each spinous process
• Blend with supraspinous ligament
posteriorly and ligamenta flava anteriorly
on each side

19. Thank you for your
attention