13 - Vertebral Column and Musculature Flashcards
What do I need to know?
- recognise different vertebrae and related their characteristics to function
- how the spinal cord is positioned and protected in the vertebral canal
- how the muscles of the lower back are arranged to provide support and movement
- stability/rigidity vs flexibility
- curvatures
- lumbar vertebra
- Linkages (discs and ligaments)
- Muscles and movements
- Nerves and vessels
How does the spine share an analogy to a yacht mast and rigging?
- a (jointed) mast (vertebral column)
- spars (ribs and transverse processes)
- rigging (muscles > NOT ligaments/tendons)
- attached to the hull (pelvis)
Is the spine stable or flexible?
It is BOTH stable and flexible
What is the benefit of having muscle as ‘rigging/support the mast’ rather than tendons and ligaments?
- having muscle means you can adjust the amount of tone so the spine has some inbuilt flexibility
- without this the spine would be quite rigid
How does stiffness change as you move towards the base (pelvis) of the spine?
> stiffness of the spine increases towards the base/pelvis
this means the lumbar region is more stiff than the cervical regions
this is because there is less material up the top
our ‘mast’ is relatively flexible but with increasing stability towards the base to support weight resulting in less lateral flexion and rotation permitted
What is the biological principle?
> high stability = low manoeuvrability
> low stability = high manoeuvrability/change direction quickly
How does flexion and extension change in the cerv/thor/lumbar regions?
Same degree of flexion and extension movement in all 3 vertebrae (40 degrees)
How does lateral flexion change in the cerv/thor/lumbar regions?
cervical - 40
thoracic and lumbar - 20
How does rotation change in the cerv/thor/lumbar regions?
Cervical and thoracic both 40 degrees
In the lumbar region this dramatically drops to 5 degrees (this is less than 1 degree per vertebra, meaning the lumbar region is very stable)
What are the 4 curvatures of the spine?
- Cervical: anterior
- Thoracic: reverses and is convex towards the posterior
- Lumbar: Anterior
- Sacral: Posterior
> is 9 vertebrae but is compressed and fused (variability among people)
> sacrum is 5 bones coccyx is 4
Lateral curvature?
Scoliosis
Increases Thoracic curvature?
Kyphosis / Kyphotic Spine
Increased Lumbar curvature?
Lordosis
> occurs in pregnant women to balance over the vertebral bodies
How do the curvatures of the spine arise?
We are NOT born with them. They occur by us standing up and by 10 years a child has an adult spine.
The bone remodels and changes shape as depending on the mechanical forces
What is the consequence of the lumbar curvature?
- as the lumbar curvature is anterior, it places vulnerable internal soft organs at some danger
- means the AORTA, which sits in front of the vertebral body, is positioned more to the anterior surface than the posterior
Where is the centre of gravity relative to the vertebral bodies?
- spinous processes are posterior vertebral body is considerably anterior
- centre of gravity is more posterior through the vertebral body than dead centre
- in an upright position we are standing over and balance over the vertebral bodies
Consequence of putting our centre of gravity over the vertebral bodies?
- means we can stand upright without excessive pressure on toes or heel
- it also minimises energy expenditure
- when we lean forwards and move away from the vertebral column THEN we expend energy to stay upright
What are the 7 parts of a typical vertebra?
- Vertebral body
- Arch
- Superior and Inferior Articular Processes
- Transverse Processes
- Spinous processes
- Pedicles
- Laminae
Vertebral Body?
- mostly spongy bone
- has a posterior depression for spinal cord
- has a smoother edge but a rough central region as there was a cartilage plate here to begin with and the fibres went from the bone into the cartilage. When the cartilage was taken out/dried out it leaves a rough dry surface
Superior and Inferior Articular Processes
- Where the lamina and pedicles meet
- on the inferior and superior surfaces are facets (part of the synovial joint between 2 adjacent vertebrae)
Transverse Processes
Where the lamina, pedicles and inf/sup articular processes meet. Project laterally
Spinous Process
Project posteriorly from the top of the arch
> in the lumbar region are flat and wide
> in the thoracic region they face inferiorly and overlap each other
Pedicles
The 2 pillars of arising from the vertebral body that make up the start of the arch
Laminae
Top bit of the arch
Where does the spinal cord run?
In the vertebral foramen (and cauda equina after L1)