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Functional anatomy > WEEK FOUR: Spinal mechanics and posture > Flashcards

WEEK FOUR: Spinal mechanics and posture Flashcards

1
Q

Is posture a dynamic process?

A

Yes

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2
Q

Explain centre of gravity

A
  • Centre point where all of our mass is distributed.
  • Maintain centre of gravity in an area within or over the base of support
  • Segments above the base can be adjusted to bring the body back into balance
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3
Q

Explain the base of support

A
  • Area defined by feet (width)
  • Walking sticks and walking frames become base of support.
  • Walking aids increase the area of the base of support
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4
Q

Explain the line of gravity

A
  • Imaginary line that extends from the CoG to the ground.

- AKA centre of gravity projection

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5
Q

Where is the centre of gravity in the anatomical position?

A
  • S2, just behind the belly button.

- Differs slightly between each person

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6
Q

Explain where the centre of gravity is when we move forward?

A
  • CoG will move in front of body (outside body). Projection goes in front of feet
  • Less stable.
  • Muscles need to work harder to maintain position because more movement
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7
Q

In an idealised posture, the Line of Gravity drops in the middle between what bilateral points?

A
  • The mastoid processes (pressure point behind ears)
  • A point anterior to the shoulder joints
  • A point posterior to the hip joints
  • A point anterior to the knee joints
  • A point anterior to the ankle joints
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8
Q

What makes the idealised posture ‘ideal’?

A
  • Minimal energy and muscle contraction required to maintain posture (equilibrium)
  • Protects supporting structures against injuries and progressive deformity
  • Optimal for thoracic and abdominal organs
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9
Q

What role do the muscles play in posture?

A
  • All of the muscles constantly adjust to maintain equilibrium
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10
Q

What are the factors contributing to static balance?

A
  • The muscles activated in static balance forming the postural tone to keep body from collapsing in response to the pull of gravity
  • So the motor control and strength of these muscles
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11
Q

Explain postural sway

A
  • No posture is absolutely static, constant sway around any chosen position
  • ## Inverted pendulum theory: Lots of mass on top, base at bottom. Mass sways around fixed point on ground
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12
Q

Can measuring the postural sway help to diagnose neurological disorders?

A

Yes

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13
Q

What is our postural sway affected by?

A

The position of other parts of the body.

If put hands in front = greater postural sway

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14
Q

Name 3 out of the 6 factors that affect posture and compensatory change?

A
  • Emotion
  • Forces applied by body structures (muscles, ligaments)
  • Forces applied by gravity, wind or other external forces
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15
Q

Name the rest of the 6 factors that affect posture and compensatory change?

A
  • Mechanics of joint and lever systems
  • Extraneous factors: Pain, pregnancy, obesity, holding a heavy box
  • Changes in positions of specific joints and regions: Result in compensatory changes to the positions of other joints or regions
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16
Q

Explain the concept of balance. When is it affected?

A
  • The ability to maintain posture
  • Balance is affected when line of gravity moves outside of the base of support.
  • Means we are more mobile but also have the potential to loose balance
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17
Q

Explain what happens with our balance when we go from sitting to standing

A
  • Decrease base of support
  • Centre of gravity also increases in height.
  • Decreases stability but increases mobility
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18
Q

Explain what happens with our balance when we go from standing to walking

A
  • Unsteady base of support because it’s always changing
  • CoG is always moving and always moving forward
  • For balance, we have to fall over our BoS
  • Controlled falling: As CoG moves forward to compensate, BoS also moves
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19
Q

What does postural awareness rely heavily on?

A
  • Sensory feedback

- Vision, vestibular system and somatosensory info.

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20
Q

Explain vision in terms of postural awareness

A
  • For reference system/point of where everything is around us and in relation to us
  • Most important one
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21
Q

Explain the vestibular system in terms of postural awareness

A
  • Info in ears. Fluid with senses in it that tell us where our head is in relation to our body
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22
Q

Explain the somatosensory info in terms of postural awareness

A
  • Info. from joint, muscle and skin receptors.

- Proprioception

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23
Q

Explain the four main causes of abnormal posture

A
  • Pathology (injury) of joints, muscles, NS
  • Lack of, or distorted awareness of body position
  • The learning over a long period of a particular abnormality, such that it becomes the norm. Positive feedback
  • Asymmetries or imbalances of forces acting on specific joints or regions in “non-optimal” postures must be compensated for by asymemtries/imbalances etc.
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24
Q

Name the three most common abnormal postures

A
  • Kyphosis
  • Lordosis
  • Scholiosis
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25
Q

Explain Kyphosis

A
  • An exaggerated curve in the thoracic region (slumped)
  • Common in older people (intervertebral discs degenerate) and sitting jobs (something too far away or too far in front of them).
  • Flexion
  • Sagittal plane
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26
Q

Explain Lordosis

A
  • When pregnant & obesity. Tight muscles (erector spinae)
  • Exaggerated lumbar spine curve.
  • Hyper lordotic position
  • More mass anteriorly, compensate by leaning back. Change CoG.
  • Sagittal plane
27
Q

Explain Scholiosis

A
  • Leg length inequality
  • Can have it at any region of the spine
  • S is in frontal plane
28
Q

What are the 4 forces on the lumbar spine?

A
  • Disc sheer force
  • Disc compressive force
  • Erector spinae force
  • Moment due to applied load
29
Q

Why are the intervertebral discs particularly important? Why are they particularly prone?

A
  • Important for integrity of spine

- Particularly prone because much more force going through it

30
Q

What happens when we load up the body?

A
  • Because forces going through the lumbar area, contractions from muscles (erector spinae) to compensate to maintain posture and balance.
  • Contractions compress discs and are under a lot of force
31
Q

What main force occurs during flexion?

A
  • Sheer force, discs want to move out
32
Q

Where do discs most commonly herniate?

A
  • Most commonly around the lumbar spine because discs are bigger
  • Will herniate posterior laterally during flexion
33
Q

Explain the concept of why you’re taller in the morning?

A
  • Because discs are on constant load during the day, fluid in middle slowly seeps out into outer space around disc.
34
Q

Does sitting or standing create more pressure on the discs?

A

Sitting

35
Q

Why should you not lift at arms length?

A

Centre of gravity is further away from base of support, more work for muscles to maintain posture

36
Q

Why should you not keep your legs straight when lifting?

A
  • causes shearing and compression force
37
Q

What should you remember when lifting heavy objects and why?

A
  • Keep load close to body to keep CoG low and over base of support
  • Squat down to lower CoG and increase stability
38
Q

Describe the concept of viscoelastic creep?

A
  • If stretch passive structures such as discs and ligaments over along period of time, then get reset to become longer.
  • Occurs when: Holding flexed positions. Mainly for ligaments that run down back
  • No longer useful at maintaining stability of spine. Rely much more on muscles, will get back pain
39
Q

Why is it called a viscoelastic creep?

A
  • Have visco (fluid) elastic type properties

- Creep: Ligament gets longer and longer

40
Q

What is muscle coactivation?

Where do we want this especially?

A
  • Where both the agonist and antagonist are activated at the same time.
  • Want it in the trunk to stay in posture/position
41
Q

Explain the concept of intra-abdominal pressure?

Why do we want this pressure?

A
  • Increase intra-abdominal pressure to get coactivation by by embracing the spine.
  • Want this pressure to increase the stability of the spine
42
Q

What is abdominal bracing and why do we use it?

A
  • Uses the transverse abdominis

- Stiffens like a corset around the spine to offer protection and increase stability

43
Q

Does abdominal bracing cause an increase in blood pressure?

A

No

44
Q

Why is the pelvic tilt important?

A

Can change position of lumbar spine and can be implicated in back pain

45
Q

What are the 5 major muscle groups that align the pelvis?

A
  • Rectus abdominis
  • Iliopsoas
  • Rectus femoris
  • Hamstrings
  • Gluteals
46
Q

Does the anterior pelvic tilt increase or decrease lumbar lordosis? What does this mean?

A
  • Increases lumbar lordosis.

- Extends lumbar spine

47
Q

What occurs if the anterior pelvic tilt is maintained?

A
  • Back extensors and hip flexors loose flexibility or become tight.
  • Hamstrings and abdominals become lax/loose and weak
48
Q

Does the posterior pelvic tilt increase or decrease lumbar lordosis? What does this mean?

A
  • Decreases lumbar lordosis

- Slumped, starts to straighten spine

49
Q

What occurs if the posterior pelvic tilt is maintained?

A
  • Hip flexors and lower back muscles become lax/loose, weak.

- Abdominals and hamstrings become tight

50
Q

What is the anterior pelvic tilt corrected by?

A
  • Strengthening hip extensors and abdominals. Stretching the lower back and hip flexors.
51
Q

What is the posterior pelvic tilt corrected by?

A
  • Strengthening back extensors and hip flexors. Stretching the hip extensors.
52
Q

Why do the hamstrings have a major effect on the configurations of the spine and pelvis?

A
  • Because they cross both the hip and knee joints.
53
Q

What is the aponeurosis?

A
  • A flat sheet of connective tissue used for muscle insertion
54
Q

Muscles of the vertebral system are simple, having only one superior and inferior attachment. True or false?

A
  • False
55
Q

The internal oblique abdominal inserts on the:

A
  • costal cartilage of the 8th, 9th and 10th ribs and linea alba
56
Q

The sternocleidomastoid has it’s superior attachment where?

A
  • On the mastoid processes
57
Q

What is the linea alba?

A
  • A narrow, vertical, fibrous strip used to attach muscle sheaths of the left and right rectus abdominis
58
Q

What depresses the rib?

A
  • Internal intercostals
  • Serratus posterior inferior
  • transversus thoracis
59
Q

What part of the IV disc is thicker?

A
  • The anterior part is thicker than the posterior.
60
Q

From C7 onwards, the ligamentum nuchae is formed as a continuation of which ligament?

A

The supraspinous ligament

61
Q

What are the functions of the anterior and posterior ligaments? What movements would these ligaments restrict?

A

Anterior: To stabilise and prevent movement. Stop excessive extension
Posterior: Reinforce the intervertebral discs. Stop excessive flexion

62
Q

What is the function of the iliopsoas

A

Flexes the hip

63
Q

How do the muscles of the abdominal wall work with the back muscles in bending forwards, backwards and side to side?

A

Stabilise and create compression to support spine.

Functional anatomy (4 decks)

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