What forms the body's major axial support?
The vertebral column
The vertebral column protects what and allows what to branch out from where through openings between adjacent vertebrae?
1. Protects the spinal cord.
2. Allows spinal nerves to branch out from the cord through openings between adjacent vertebrae
How many bones make up the vertebral column?
24 single bones and 2 fused bones
What are the 24 single bones making up the vertebral column called?
Vertebrae
What are the 2 fused bones making up the vertebral column?
1. Sacrum
2. Coccyx
Of the 24 single vertebrae, the 7 bones of the neck are called what?
Cervical vertebrae
Of the 24 single vertebrae, the next 12 bones are called what?
Thoracic vertebrae
Of the 24 single vertebrae, the 5 bones supporting the lower back are called what?
Lumbar vertebrae
Each vertebrae is separated from the next by what?
intervertebral discs
Intervertebral discs are made up of what?
fibrocartilage
The intervertebral discs cusion what and absorbs what?
1. Cushion the vertebrae
2. Absorb shocks
Each disc is composed of how many major regions?
2
What are the 2 major regions in an intervertebral disc?
1. nucleus pulposus
2. anulus fibrosus
The nucleus pulposus is made out of what?
Gelatinous material
The nucleus pulposus behaves like what common household toy?
rubber ball
What is the anulus fibrosus shaped like and what is made out of?
Shaped like a ring and is made out of collagen fibers
The anulus fibrosus stabilizes what and contains what?
1. Stabilizes the discs
2. Contains the nucleus pulposus
What 3 things happen to the discs as a person ages (i.e. disc thickness, water content, compressibility)?
1. Water content of the discs decreases
2. Discs become thinner
3. Discs become less compressible
What 5 things predispose an older person to a having a ruptured disc?
1. Water content of the discs decreases
2. Discs become thinner
3. Discs become less compressible
4. Weakening of the ligaments in the vertebral column
5. Weakening of the tendons in the vertebral column
In a herniated or ruptured disc, what commonly happens to anulus fibrosus?
It ruptures.
In a herniated disc, with the rupturing of the anulus fibrosus, what happens to the nucleus pulposus resultantly?
It protrudes or herniates through the disc.
Why is a herniated disc painful?
The nucleus pulposus compresses the adjacent nerves, causing pain.
What are the 2 primary curvatures of the spine?
1. Thoracic curvature
2. Sacral curvature
What are the thoracic and sacral curvatures considered primary curvatures?
They are present and well developed at birth.
What are the 2 secondary curvatures?
1. cervical curvature
2. lumbar curvature
When does the cervical curvature become more prominent?
When the baby begins to hold its head up independently .
When does the lumbar curvature become more prominent ?
When the baby begins to walk.
What are 3 abnormal spinal curvatures?
1. Scoliosis
2. Kyphosis
3. Lordosis
Abnormal spinal curvatures may result from what 2 things?
1. disease
2. poor posture
When the fibrous disc is properly positioned, are the spinal cord or peripheral nerves impaired in any way?
No.
Remove the intervertebral disc, and put the two vertebrae back together. What happens to the nerve?
There is no separation in the vertebrae and the nerves touch.
What would happen to the spinal nerves in areas of malpositioned, or "slipped," discs?
The nerves would get pinched, causing pain.
What are the 5 regions in a vertebral column?
1. Cervical curvature
2. Thoracic curvature
3. Lumbar curvature
4. Sacral curvature
5. Coccyx
All vertebrae have what 7 features in common?
1. Body
2. Vertebral arch
3. Vertebral foramen
4. Transverse processes
5. Spinous processes
6. Superior and inferior articular processes
7. Intervertebral foramina
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The vertebral foramina act as what for what?
Act as a conduit for the spinal cord.
The superior and inferior articular processes enable articulation with what?
Enable articulation with adjacent vertebrae.
Each processes (superior and inferior) has an articular surface that is covered with what cartilage type?
Hyaline cartilage
The intervertebral foramina allow what to leave what between adjacent vertebrae?
Allow spinal nerves to leave the spinal cord between adjacent vertebrae.
How many vertebrae make up the cervical vertebrae?
7
What are the vertebrae making up the cervical vertebrae called? (Hint: numbers)
C1-C7
The cervical vertebrae forms what portion of the vertebral column?
Neck
Which 2 cervical vertebrae are highly modified to perform special functions?
1. Atlas
2. Axis
What cervical vertebrae number is the atlas?
C1
What cervical vertebrae number is the axis?
C2
What is the most notable feature missing from the C1 vertebra?
A body
The lateral or transverse processes of the atlas contains what?
Large concave depressions
The large concave depressions in the lateral or transverse process receive what condyles from where?
Receive the occipital condyles of the skull.
The atlas enables what function?
One to nod "yes"
The axis acts as what?
A pivot
The axis, acting as a pivot, allows what 2 things to happen?
1. Allows atlas to rotate
2. Allows skull to rotate
What particular feature of the axis acts as the pivot point?
the dens
The articulation between C1 and C2 allows you to do what?
Rotate head from side to side
Cervical vertebrae (C3-C7) are distinguished from the thoracic and lumbar vertebrae by what 4 features (i.e. size and weight, shape of vertebral foramen, length of spinous process, and shape of spinous process)?
1. Smallest and lightest vertebrae
2. Vertebral foramen is triangular
3. Spinous process is often short
4. Spinous process is often bifurcated
Of cervical vertebrae C3-C7, which one has a substantially longer and unbranched spinous process?
C7
Why is C7 commonly called the vertebra prominens?
Because the spinous process of C7 is visible through the skin at the base of the neck.
Transverse foramina in C3-C7 allow what to pass to which body part?
Allow vertebral arteries to pass superiorly on their way to the brain.
How many vertebrae are there in the thoracic region of the vertebral column?
12
The thoracic vertebrae are referred to as what? (Hint: numbers)
T1-T12
What 5 features separate the thoracic vertebrae from the cervical vertebrae (i.e. size of the body, shape of the body, costal facets presence-yes or no, shape of vertebral foramen, spinous process shape)?
1. Larger body
2. Body is heart-shaped
3. They have costal facets.
4. Vertebral foramen is oval or round
5. Spinous process is long with a downward hook
What is the function of the costal facets in the thoracic vertebrae?
Articulation with the ribs
The superior and inferior costal facets of the thoracic vertebrae connect to what part of the ribs?
Heads of ribs
Articular facets on the transverse processes of the thoracic vertebrae articulate with what of the ribs?
Tubercles of the ribs.
The thoracic vertebrae form what 2 parts of the body?
1. Thoracic part of the spine.
2. Posterior aspect of the rib cage.
What is the only vertebrae group that articulates with the ribs?
Thoracic vertebrae.
How many vertebrae are there in the lumbar region of the vertebral column?
5
The lumbar vertebrae are referred to as what? (Hint: numbers)
L1-L5
What are the 2 defining features of the lumbar vertebrae that set them apart from the other two sets (i.e. shape of body, shape of spinous process)?
1. Massive block-like bodies
2. Hatchet-shaped spinous processes
Which structural features reduce the mobility of the lumbar vertebrae?
Superior and inferior articular facets
Which group of vertebrae is the sturdiest?
Lumbar vertebrae
Why are the lumbar vertebrae the sturdiest?
Because most stress on the vertebral column occurs in the lumbar region
At which specific vertebra does the spinal cord end?
L2
Even though the spinal cord ends at the L2 vertebra, what particular feature of the spinal cord still extends past that vertebra?
Outer covering of the cord
The outer covering of the cord that extends passed the L2 vertebrae is filled with what?
Cerebrospinal fluid
Between which 2 sets of vertebrae is the lumbar puncture adminstered?
1. Between L3 and L4
2. Between L4 and L5
What is the purpose of the lumbar puncture?
To examine the cerebrospinal fluid
Between which 2 sets of vertebrae is the "saddle block" anesthesia for childbirth adminstered?
1. Between L3 and L4
2. Between L4 and L5
Why is the lumbar puncture or "saddle block" anesthesia administered between vertebrae L3 and L4 or L4 and L5?
The spinal cord ends at the L2 vertebra, so there is a very low chance of injuring the spinal cord.
Describe the sacrum.
A composite bone formed from the fusion of 5 vertebrae.
Superiorly, the sacrum articulates with what specific vertebra, and inferiorly, what does it connect with?
Articulates with L5 vertebra and connects with the coccyx.
The median sacral crest is a remnant of what processes?
A remnant of the spinous processes of the fused vertebrae.
The alae is formed by the fusion of what processes?
Transverse processes
The alae articulates with which bones?
Articulate with the hip bones.
The four ridges of the anterior sacrum are the result of which type of fusion?
Vertebral fusion
What is located at either ends of the four ridges on the anterior sacrum?
Sacral foramina
The sacral formaina functions to allow what 2 things to pass?
1. Blood vessels
2. Nerves
The vertebral canal continues inside the sacrum and is now referred to as what?
Sacral canal
The sacral canal (aka vertebral canal) terminates at which particular feature in the coccyx?
Sacral hiatus
In the sacrum, what is an important feature for obstetricians?
Sacral promontory
The coccyx is formed from the fusion of what range of vertebrae?
3-5
The vertebrae that form the coccyx are shaped in what 2 ways?
1. Small
2. Irregular
The coccyx is literally what?
human tailbone
Describe the human tailbone in regards to other vertebrates?
It is a vestige of the tail that other vertebrates have.
How is the coccyx attached to the sacrum?
By ligaments
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