Vertebrae Anatomy
How many thoracic vertebrae?
12
Number of vertebrae in adult human body (after age 30)
26
Number of vertebrae in human body (before age 30)
33
How many coccygeal vertebrae before age 30?
4 (fuses to one coccyx bone eventually)
How many lumbar vertebrae?
5
How many sacral vertebrae before age 30?
5 (fuses to form sacrum)
How many cervical vertebrae?
7
What three things does a typical vertebra have:
A vertebral body A vertebral arch 7 processes
Why do vertebrae become larger as you go down the vertebral column till the sacrum?
Because as you go down the vertebral column, each vertebra bears more weight so they need to be larger to support the weight
The transverse foramen are what in C7 compared to all other cervical vertebrae?
C7's transverse foramen is smaller and sometimes not present
Why is the atlas (C1) atypical?
Does not have body or spinous process
What does the vertebral body look like?
Its massive, somewhat cylindrical and its the anterior part of the bone
Where does the vertebra reach the maximum size?
Just superior to the sacrum
Scoliosis:
Known as the S curve ; curvature may be in the thoracic and/or lumbar region
Where do the transverse processes of the cervical vertebrae end?
Laterally in two projections: an anterior tubercle and posterior tubercle
What do the tubercles provide attachment for?
Levator scapulae and scalenes
What is the epiphysial rim?
Ring of smooth bone
Purpose of the anular epiphysis:
Serves as growth zones Provide some protection to the vertebral bodies and permit some diffusion of fluid between the IV disc and the blood vessels in the vertebral body
Why is there less vertebrae after age 30?
The 5 sacral vertebrae fuse to form sacrum The 4 coccygeal vertebrae fuse to form coccyx
Where does the lumbosacral angle occur at?
The junction of the long axes of the lumbar region of the vertebral column and sacrum
Why does the vertebra reach max size superior to the sacrum?
The weight gets transferred to the pelvic girdle and sacroiliac joints.
What do the 25 cervical, thoracic, lumbar, and first sacral vertebrae articulate with?
The zygapophyseal (facet) joints
What does the trabecular bone consist of
Trabeculae
What does the vertebral body consist of?
Trabecular bone enclosed by a thin layer of compact bone
The dens lies where compared to the spinal cord
anterior to the spinal cord
C1 and C2
are atypical
C3-C7
are typical cervical vertebrae
C1 is called the
atlas
Both the dens and the spinal cord inside its covering (meninges) are encircled by the
atlas (C1)
C2 is known as the
axis
Why are the curves important?
because they allow spine to endure force without allowing additional stress to other body structures
Why are the cervical and lumbar known as secondary curves?
because they aren't present at birth. they begin to develop as infant bends head backward, move, crawl and weight bear, they start to develop
Lordosis:
bend backward cervical and lumbar are convex anteriorly and concave posteriorly
cervical vertebrae are located where
between the cranium and the thoracic vertebrae
C2 has a large what
bifid spinous process
What are the vertebral end plates remnants of?
cartilaginous model from which the bone develops
Which curves are known as your secondary curves?
cervical and lumbar
Which curves are shaped similarly?
cervical and lumbar sacral and thoracic
As infant bends backwards ,
cervical curve forms
spinous and transverse processes provide attachment for what
deep back muscles
What is the superior and inferior surfaces of the vertebral body covered with?
discs of hyaline cartilage AKA vertebral end plates
In museum skeletal specimens, this cartilage is absent, except at the periphery where a what is present?
epiphysial rim
Poor body mechanics result in curves being ?
excessive (Lordosis and Kyphosis)
Purpose of facet joints
facilitate and control the vertebrae column flexibility
Purpose of the vertebral body
gives strength to the vertebral column and supports body weight
the relative thickness of the IV disks, the nearly horizontal orientation of the articular facets, and the small amount of surrounding body mass give the cervical region what compared to other vertebral regions?
greatest range and variety of movement
What does atlas have in place of body?
lateral masses that bear the weight of the cranium
C7 is characteristic of a
long spinous process
Since the transverse processes come from the lateral masses, they are what compared to the vertebrae below?
more laterally placed
the bifid process can be felt deep in the
nuchal groove
The transverse ligament of the atlas runs from
one lateral mass of the atlas to the other, passing between teh dens and pinal cord
The most distinctive feature of each cervical vertebra is the
oval foramen transversarium (transverse foramen)
The transverse ligament prevents what
posterior (horizontal) displacement of the dens and anterior displacement of the atlas
Where is the vertebral arch located?
posterior to the vertebral body and consists of two right and left pedicles and laminae
Since the atlas is the widest, it allows for what?
provides increased leverage for attaching muscles
What do the spaces in between the trabeculae consist of?
red bone marrow -which is one of the most blood forming tissues of the mature individual
C1 carries the cranium and does what on C2
rotates on C2
Which curves are known as your primary curves?
sacral and thoracic , because they are present at birth
Vertebra gradually become larger until the _________?
sacrum
Vertebra gradually become smaller after the _________ till the _______?
sacrum to the apex of the coccyx
Purpose of dens
serves as the pivot point about which the rotation of the head occurs
What are the pedicles?
short, cylindrical process that project posteriorly from the vertebral body to meet the laminae they transfer muscle forces from posterior element of body
Then what goes through C7's transverse foramen?
small accessory veins
Cervical IV disks are what compared to inferior regions?
smaller
are cervical vertebrae small or big?
smallest of the 24 movable vertebrae
what are the purpose of the superior articular facets?
so C1 (atlas) can rotate on
the nuchal groove is the
superficial vertical groove of the neck
the axis has two large, flat bearing surfaces known as the
superior articular facets
How are the trabeculae oriented?
tall vertical trabeculae intersects with short horizontal trabeculae with spaces in between
What is the epiphysial rim derived from?
the anular epiphysis
Distinguishing feature of C2
the blunt tooth like dens (odontoid process) which projects superiorly from its body
The superior and inferior epiphyis unite with what?
the centrum
the transverse processes of the atlas arise from
the lateral masses
As infant begins to weight bear,
the lumbar curve forms
The super articular surfaces of the lateral masses articulate with
the occipital condyles (two large cranial protuberances) at the sides of the foramen magnum
What is the dens held in position against?
the posterior aspect of the anterior arch of the atlas by the transverse ligament of the atlas
What is the centrum?
the primary ossification center for the central mass of the vertebral body
cervical vertebrae form what:
the skeleton of the neck
What does the vertebral canal consist of?
the spinal cord, the roots of the spinal nerves, along with meninges, fat, and vessels that surround and serve them
the axis is the what of all cervical vertebrae
the strongest
What forms the vertebral foramen?
the vertebral arch and the posterior surface of the vertebral body
What passes through the transverse foramen of the cervical vertebra besides C7?
the vertebral arteries and their accompanying veins
The posterior arch of the atlas has a large groove because?
the vertebral artery runs through it on the superior surface and the C1 nerve also runs through this groove
Since the transverse processes are more laterally placed, this feature makes the atlas what compared to all other cervical vertebrae?
the widest
what is the purpose of spinous and transverse processes
they serve as levers, facilitating the muscles that fix or change the position of the vertebrae
However, IV disks are relatively _____ compared to the size of the vertebral bodies they connect
thick
Kyphosis
thoracic and sacral : convex posteriorly and concave anteriorly
Why do they have large vertebral foramina?
to accommodate the cervical enlargement of the spinal cord as a consequence of the region's role in the innervation of the upper limbs
What is the laminae?
two broad, flat plates of bone
Where do the pedicles and laminae meet?
unite in the midline
Therefore, C7 is called the
vertebra prominens
C3-C7 have large
vertebral foramina
