Therex for Neck and Trunk

Question 1

What is the coupled motion of the AA joint?

Answer 1

• Rotation occurs at the AA joint (C1-C2)
• C1-C2 motion coupled with vertical translation along the vertical (y-axis) and a degree of anteroposterior displacement

Question 2

What is the coupled motion of the subaxial spine?

Answer 2

• Lateral flexion to the left = movement of spinous process to the right.
• 2 degrees of coupled axial rotation (to same side as lateral bend?) for every 3 degrees of lateral bending = 2:3 ratio

Question 3

Where does flex/ext occur when the spine unloaded?

Answer 3

• first 50-60 degrees occur in the lumbar spine
• pelvic tilting allows further forward motion
• trunk flexion and pelvic tilting occurs simultaneously during lifting and lowering

Question 4

How does the thoracic spine contribute to flex/ext?

Answer 4

contributes little secondary to structure (ribs stabilize thoracic vertebrae)

Question 5

How is flexion initiated and what else occurs?

Answer 5

1. initiated by abdominals and vertical portion of psoas
   -weight of upper body produces further flexion which is controlled by gradually increasing activity of erector spinae eccentrically
2. posterior hip (muscles?) control tilting
3. Superior vertebra will anterior tilt and forward glide:
   -widening the intervertebral foramina 24%
   -adds compressive forces on the
   anterior aspect of the anterior segment moving the nucleus pulposus posteriorly
4. tensile forces placed on posterior annulus, ligamentum flavum, capsule and posterior longitudinal ligament (PLL)
5. Central Canal is widened

Question 6

What occurs during extension of the spine?

Answer 6

• Sequence of muscle activity reverses
  1. gluteus max, HS activate early to initiate extension through posterior pelvic roation
  2. Paraspinals then become activated and increase activity until movement complete
  3. Superior vertebra will tilt and glide posteriorly and intervertebral foramina narrowed up to 20%
  4. The central canal is also narrowed
  5. Nucleus pulposus moves anteriorly

Question 7

Where does lateral flexion predominate (initiate) and what else occurs?

Answer 7

• Predominates from either the thoracic or lumbar spine
  1. Thoracic spine is coupled with same side rotation (esp upper b/c frontal orientation of facets)
  2. Transversospinal muscles and abdominals active- ipsilateral initiate and contralateral control
  3. In lumbar spine lateral flexion is coupled with opposite side rotation
  4. Superior vertebra will translate, tilt and rotate over inferior vertebra
  5. Concavity towards, convexity opposite
  6. Tensile forces on convexity, compressive forces on concavity
  7. Extension in ipsilateral facet
  8. Flexion on contralateral facet

Question 8

What is lumbar-pelvic rhythm?

Answer 8

characteristic combination of ranges to improve overall motion

Question 9

What is an anterior pelvic tilt?

Answer 9

1. it may be structural or functional but most are functional
2. involves increased extension of lumbar spine, and an anterior tipping of the pelvis

Question 10

What are the biomechanical consequences of lumbar extension?

Answer 10

1. Nuecleus pulposus moves anteriorly
2. decreases size of intervertebral foramen
3. transfers load from disc to apophyseal joints
4. Decreases tension on posterior connective tissue
5. stretches anterior side of annulus fibrosus

Question 11

What is a posterior pelvic tilt?

Answer 11

• involves a posterior tipping of the pelvis and a versal of the normal curve of the lumbar spine (causes flexion of spine)
• position of the pelvis determines lumbosacral angle and the amount of shear forces on the articulation of L5 on S1

Question 12

What are the biomechanical consquences of lumbar flexion?

Answer 12

1. Nucleus pulposus moves posterior
2. increases size of intervertebral foramen
3. Transfers load from facet joints to discs
4. Increases posterior connective tissue tension
5. compresses anterior annulus fibrosis

Question 13

During standing, what are the forces acting on the spine?

Answer 13

1. Body weight
2. Tension in the spinal ligaments
3. tension in the surrounding muscles
4. Intra-abdominal pressure

Question 14

What is the major form of loading on the spine during standing?

Answer 14

Axial loading

Question 15

What occurs when in good alignment during standing?

Answer 15

• postural muscles are constantly active
  1. line of gravity falls anterior to the center of lumbar vertebral bodies creating flexion moment
  2. counter balanced by ligament forces and erector spinae
  3. any displacement requires change in magnitude and direction of muscular forces = postural sway
  4. Spinal compression results from body weight + weight being held by arms/hands

Question 16

What is the role of the pelvis in standing?

Answer 16

-position of sacrum = 30 degrees forward and downward
-change in pelvic tilt results in change in center of gravity = change in muscle activity
Therefore, APT = increase in muscle activity

Question 17

Where is the mechanical stability coming from during standing?

Answer 17

• intra-abdominal pressure- coordinated contraction of diaphragm, pelvic floor and abdominals
  1. Transversus Abdominis is primary muscle responsible for Intra-abdominal pressure
• Trunk muscle co-contraction- response to spinal loading:
  1. erect standing = 100 units of loading; curl up = 200 units, bend leg raise = 140 units
• External stabilization- back belts do not increase muscle activation, do not increase lifting capacity

Question 18

What occurs when loads are added during standing?

Answer 18

• Highest loads produced by external loads = lifting objects
• Spinal muscle role in lifting
  1. spinal muscles have small moment arms with respect ot the vertebral joints
  2. have to generate large forces to counteract the torque produced about the spine by body weight and objects being lifted
  3. back muscles with a moment arm of ~6 cm must counter the torque produced by the weights of the body plus any external loads (refer to picture in notes)

Question 19

What contributes to the stability of the trunk?

Answer 19

Refer to tables 14.2, 14.3, 14.4 in book

• Global muscle activity
  1. superficial muscles- provide stabilization of trunk as overall unit
  2. Deep/segmental muscle activity- deep muscles- transverse abdominis, multifidus- stabilize individual segments

Question 20

What are the exercise guidelines for neck and trunk?

Answer 20

1. Kinesthetic awareness- neutral spine, posture control, lumbar and or cervical stsabilization
2. Mobility/flexibility- stretching and mobilization
   - thoracic extension- stretch anterior trunk
   - axial extension- stretch scalenes
   - capital flexion- stretch rectus capitus
   - lumbar flexoion- stretch erector spinae
3. Muscle performance- strength, power, endurance and stability
   - upper abdominals crunches
   - lower abdominals- neutral spine, pelvic tilts, progressive limb loading
   - spinal extensors-
4. Cardiopulmonary endurance
5. functional activities: rolling, sit to stand, body mechanics, lifting reaching, pushing, pulling