This document discusses the anatomy and biomechanics of the spine. It begins by identifying the main regions and curves of the spine, including the cervical, thoracic, lumbar, sacral, and coccygeal regions. It then discusses the normal curvatures seen in the cervical and lumbar regions. The rest of the document details the structures that make up each vertebral segment including the intervertebral discs and facet joints. It explains the biomechanics of spinal movement including coupling and the roles of the muscles in flexion, extension, and lateral bending. In summary, the document provides a comprehensive overview of spinal anatomy and function.

1. Dr. Chhavi SinghTomar
Asst. Prof. /Vice – Principal
Nims College of Physiotherapy &
OccupationalTherapy
Nims University

2. Identify the main structures of the spine.
Identify normal curvatures of the spine, including the cervical, thoracic, and
lumbar regions.
Identify mobile segment.
Ligaments of spine.
To know about different spine movements.
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3. Introduction
“ The vertebral column also known as back bone is a complex structure which meet
the demands of mobility and stability of the trunk and extremities, also protect the
spinal cord”
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4. Cervical (neck) - 7 vertebrae (C1-C7)
Thoracic (chest) - 12 vertebrae (T1-T12)
Lumbar (lower back) - 5 vertebrae (L1-L5)
Sacral (pelvis) - 5 fused vertebrae (S1-S5)
Coccygeal (tail) - 4 vertebrae (Co1-Co4)
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5. Seven vertebrae
More flexible
Supports the head
Wide range of motion
 Rotation to left and right
 Flexion Up and down
 Lateral bending
Peripheral nerves
• Shoulder, Chest and diaphragm
• Arms
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6. Twelve vertebrae
Mid-back or dorsal region
Ribs attached to vertebrae
Relatively immobile
Peripheral nerves
• Intercostal
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7. Lower back
Five vertebrae
Carries the weight of the upper body
• Larger, broader
Peripheral nerves
• Legs
• Pelvis
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8. Sacrum
• Triangular structure
• Base of the spine
• Connects spine to pelvis
• Nerves to pelvic organs
Coccyx
• Few small bones
• Remnant of tail
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9. Two types of curvature
1. Primary curvature
2. Secondary curvature
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10. Called khypotic curves
During fetal development, the spine assumes the shape of the letter "C,"
This C-shaped curve is the primary curve of the spine and is well-suited for
the fetus to confine in the womb.
• Develops in pregnancy -mid term
• Concave anteriorly
• Convex poseriorly
• Primary curvature remains in adults as Thoracic and sacral curvatures
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11. The cervical curve of the neck region is the first to develop.
Opposite to direction of primary curves.
Convex anteriorly
Concave posteriorly
Develops in early childhood.
i.e. cervical and lumbar curvatures
Called Lordotic curvatures
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12. “ The smallest functional unit of the spine is called as mobile segment”
Parts:
Two adjacent vertebras
Intervertebral disc
Soft tissues which secure them, i.e. Ligaments and muscles.
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13. The anterior portion of the segment is composed of
 Two superimposed intervertebral bodies
 The intervertebral disc
 The longitudinal ligaments
The posterior portion of the segment is composed of
 Vertebral arches,
 The intervertebral joints formed by the facets,
 The transverse and spinous processes,
 Ligaments
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14. 14

15. are designed to bear mainly compressive loads
progressively larger caudally as the superimposed weight of the upper body
increases.
lumbar region are thicker and wider ; their greater size allows them to
sustain the larger loads to which the lumbar spine is subjected.
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16. Two principle functions:
I. To separate two vertebral bodies thereby increasing available motion
II. Transmit load from one vertebral body to next.
Three main parts
1. Nucleus pulposus
2. Annulus fibrosus
3. Vertebral end plates: Cartilaginous layer covering the superior and
inferior surfaces of the disc
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18. Cervical Spine:
Two uppermost cervical vertebrae (Cl and C2), facets are parallel to the
transverse plane
The facets of C3 to C7 are oriented at a 45° angle to the transverse plane and are
parallel to the frontal plane allowing flexion, extension, lateral flexion and rotation.
Thoracic Spine:
The facets oriented at a 60° angle to the transverse plane and at a 20° angle
to the frontal plane.
allows lateral flexion, rotation, and some flexion and extension.
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19. Lumbar Spine:
The facets are oriented at right angles to the transverse plane and at a 45°
angle to the frontal plane.
This alignment allows flexion, extension, and lateral flexion, but almost no
rotation.
The lumbosacral joints differ from the other lumbar intervertebral joints in that
the oblique orientation of the facets allows appreciable rotation.
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21. The facets guide movement of the motion segment and have a load- bearing
function, and may have some role in the lateral stability of the motion
segment
Load sharing between the facets and the disc varies with the position
and the health of the spine.
The loads on the facets are greatest with axial rotation of the spine.
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22. With disc degeneration, a greater amount of force is transferred to the facet
joints, thereby redistributing the load through the motion segment .
Because the facets are not the primary support structure in extension, if total
compromise of these joints occurs, an alternate path of loading is established.
This path involves the transfer of axial loads to the annulus and anterior
longitudinal ligament as a way of supporting the spine.
High loading of the facets is also present during forward bending,
coupled with rotation.
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23. They play an important role in resisting shear forces.
For Example:
 This function is demonstrated by the fact that patients with deranged arches
or defective joints (e.g., from spondylolysis and spondylolisthesis) are at
increased risk for forward displacement of the vertebral body.
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24. Serve as sites of attachment for the spinal muscles that, when activated
 Initiate spine motion
 Provide extrinsic stability.
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25. 25

27. The movements available in the vertebral column as a whole are
a. Flexion and extension
b. lateral flexion
c. rotation
Agonistic muscle initiate and carry out motion
antagonistic muscles control and modify the motion
co-contraction of both groups stabilizes the spine.
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28. The ROM differs at various levels of the spine and depends on the
orientation of the facets.
Motion between two vertebrae is small and does not occur
independently.
All spine movements involve the combined action of several motion
segments.
The skeletal structures that influence motion of the trunk are
 The rib cage, which limits thoracic motion
 The pelvis, which augments trunk movements by tilting.
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29. The vertebrae have six degrees of freedom: rotation about and translation along
a transverse, a sagittal, and a longitudinal axis.
The motion produced during flexion, extension, lateral flexion, and axial
rotation of the spine is a complex combined motion resulting from
simultaneous rotation and translation which is called as coupling.
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30.  Coupling is defined as the association of one movement about an axis
with another movement around a different axis.
 The most predominant movements that exhibit coupled behaviors are
lateral flexion and rotation.
 Pure lateral flexion and pure rotation do not occur in any region of the spine.
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31. The spinal muscles can be divided into
flexors and extensors.
The trunk muscles play an important role in the mechanical behavior of
the spine, including spine stability and intradiscal pressure.
The main flexors are the abdominal muscles and the psoas muscles.
The main extensors are the erector spinae, the multifidus, and the
intertransversarii attached to the posterior elements.
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32. When extensor muscles contract symmetrically, extension is produced.
When right and left side flexors and extensor muscles contract
asymmetrically, lateral bending or twisting of the spine is produced.
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