Download Spine Bony Anatomy

BONES OF THE
SPINE
Introductory Information
• The spine is a stack of 33 bones called vertebra held
together by ligaments and muscles.
• Between each vertebra, there is a fibrocartilage disc,
which is made mostly of protein and water.
The bones are divided into 5 sections:
•
Cervical Spine = the most superior group, a.k.a. the neck; contains 7
vertebrae
•
Thoracic Spine = the chest; contains 12 vertebrae
•
Lumbar Spine = the low-back; contains 5 vertebrae
•
Sacral Spine = Contains 5 vertebrae which are fused together into one
structure called the sacrum.
•
Coccygeal Spine = Contains 4 vertebrae which are fused together into
one structure called the coccyx (that’s your tailbone)
Spinal Curvatures:
• When viewed laterally, the spine
has 4 curvatures:
• An anterior, or convex, curve called a
lordosis is seen in the cervical and
lumbar spine.
• A posterior, or concave, curve called a
kyphosis is seen in the thoracic and
sacro-coccygeal spine.
Spinal Curvatures:
• What can cause an increase or
decrease in the spinal curvature?
• It depends on shifts in the body’s
center of gravity (e.g. with
pregnancy, weight gain, weight
loss, or trauma).
•
Function of
the spinal
column = to
maintain the
body in an
upright
position with
the brain
located over
the body’s
center of
gravity.
Bones of the Spinal Column
•
All vertebrae have:
1. A vertebral body.
2. 2 Transverse Processes (TP)= lateral bony projections that
serve as a source for ligamentous and muscular attachment.
3. Spinous Process (SP) = a posterior bony process that serves
as a source of ligamentous and muscular attachment.
4. Vertebral Foramen = where the spinal cord and nerve roots
pass.
Bones of the Spinal Column
5. Superior and inferior articulating facets = where the
vertebra articulates with the vertebrae above and below.
6. Lamina = forms the posterior portion of the vertebral
foramen.
7. Pedicles = form the lateral sides of the vertebral foramen.
8. Intervertebral Foramen (IVF) = located between each
vertebra and allows the nerve branches from the spine to
pass through.
9. Pars Interarticularis = the bony area between the
superior and inferior articulating facets
Bones of the Spinal Column
Cervical Vertebrae:
•
How many cervical vertebrae are there?
•
•
There are 7, numbered from top to
bottom (C1-C7).
What do all cervical vertebrae have?
1. A bifid (split) spinous process
2. A transverse process foramen
•
What passes through the foramen?
•
The blood vessels for the cervical spine
(particularly the Vertebral Artery)
Cervical Vertebrae:
• Atlas = the 1st cervical vertebra
• Has no vertebral body.
• Has 2 large articular facets that provide a surface
where the skull and the spinal column articulate.
Cervical Vertebrae:
• Axis = the 2nd cervical vertebra
• The atlas slides over the axis, and rests on 2
large superior articulating surfaces.
• Dens (a.k.a. Odontoid Process) = a large
bony process between the 2 articular surfaces
of the axis.
• C7 = has a very long spinous process (most
easily palpated).
Thoracic Vertebrae:
•
How many thoracic vertebrae are
there?
•
•
There are 12.
What is special about the SP’s of
Thoracic Vertebrae?
•

Thoracic vertebrae have longer
and more vertically inclined
spinous processes.
Costal Facets = articulating surfaces on the anterior lateral aspects of the
transverse processes and the superior and inferior portions of the posterior lateral
aspects of the vertebral bodies that provide the articulation for the 12 pairs of
ribs with the 12 thoracic vertebrae.
Lumbar Vertebrae:
•
How many lumbar vertebrae are there?
• There are 5.
•
What is special about them?
• They are the largest vertebrae.
•
What do lumbar vertebrae not have?
• They have no transverse process
foramen or costal facets on their bodies.
•
•
•
Sacral Vertebrae:
The 5 sacral vertebrae are separate at birth.
The bones eventually fuse together to form a large triangularshaped bone known as the sacrum.
The 2 large articular surfaces formed on the lateral aspects of
the sacrum are where the spinal column articulates with the
bones of the pelvis.
Coccygeal Spine:
•
•
The 4 coccygeal vertebrae are separate at birth.
The bones eventually fuse together to form the
coccyx, a.k.a. your tailbone.
The Intervertebral Disc (IVD)
•
The IVD is a cartilaginous disc made of mostly water and
protein.
•
There is one disc between each pair of vertebrae (except for
C1 and the skull, and any of the sacral or coccygeal
vertebrae).
•
Purpose:
1. A spacer to allow nerve roots to pass from the spinal
column to other body structures.
2. Shock absorption for the spinal column.
•
Parts of the Disc:
•
Nucleus Pulposus = the inner portion of the disc; consists of soft, pulpy,
elastic tissue.
•
Annulus Fibrosis = the other portion of the disc; cosists of fibrous tissue.
The Intervertebral Disc (IVD)
•
Parts of the Disc:
• Nucleus Pulposus = the inner portion of the disc;
consists of soft, pulpy, elastic tissue.
•
Annulus Fibrosis = the other portion of the disc;
consists of fibrous tissue.