Thoracic Spine Biomechanics

Question 1

True or False: Without a rib cage the thoracic spine would be able to withstand more force but would be far less mobile

Answer 1

False, the rib cage adds durability to the T spine but takes away mobility

Question 2

True or False: Motion at the T spine always causes motion in the sternum

Answer 2

False, there is considerable movement of the spine and sternum independent of one another

Question 3

True or False: rotation is more available in the upper and mid-thoracic region, as compared to flexion, extension and lateral flexion

Answer 3

True

Question 4

True or False: flexion/extension motion availability increases in lower thoracic spine due to facet orientation more approximating lumbar vertebra

Answer 4

True

Question 5

What is the approximate ROM of flexion/extension/rotation/lateral flexion in the T spine?

Answer 5

Flexion: 30-40 deg.
Extension: 20-25 deg.
Rotation: 30-35 deg.
Lateral flexion: 25-30 deg.

Question 6

What is the coupled rib motion with thoracic flexion?

Answer 6

-superior vertebral body motion causes anterior rotation of rib head (anterior portion of rib moves inferiorly)

Question 7

What is the couple rib motion with thoracic extension?

Answer 7

-superior vertebral body motion causes posterior rotation of rib head (anterior portion of rib moves superiorly)

Question 8

What are the primary muscles of respiration?

Answer 8

diaphragm, scalenes and intercostals

Question 9

what muscles are involved in forced inspiration?

Answer 9

serratus posterior superior/inderior, levator costarum, SCM, latissimus dorsi, iliocostalis cervicis and thoracis, pec minor and major, quadratus lumborum

Question 10

What muscles are involved in forced expiration?

Answer 10

abdominals, transversus thoracic, internal intercostals

Question 11

What are the rib mechanics of the upper, middle, and lower ribs with respiration?

Answer 11

Upper: pump handle movement (changes A-P diameter)

middle: bucket handle movement (changes A-P and transverse diameter)
lower: caliper like movement (changes transverse diameter)

Question 12

What functions as the “true” T-spine?

Answer 12

T4-9

Question 13

What are the 2 common patterns of clinical presentation for T spine pain?

Answer 13

1. pain from loading (load attenuation)

2. Symptoms related to movement/motion restrictions

Question 14

How does the T spine handle increasing load demands?

Answer 14

progressive increase in vertebral body height, end plate cross sectional area, and bone content as you travel down the T-spine help dissipate the load

The upper T spine gets 76% of compressive load transferred through vertebral body/disc complex while the lower T spine gets a greater load transferred through posterior column via interlocking lamina and facet joints

Question 15

True or False: The IV disc in the thoracic spine is thicker than cervical or lumbar spine IVDs due to the need to transfer high loads.

Answer 15

False, IVD in T spine is thinner than C spine or L spine but the annulus fibrosis is stronger and can resist rotational stress better

Question 16

True or False: The lumbar and thoracic spine mirror each other in their load distribution mechanics

Answer 16

False, L spine compressive loading is usually uniform through the vertebrae but in T spine the load becomes asymmetric when loaded outside the neutral position (which may explain the common clinical finding of mid-thoracic pain associated w/ sustained loading postures e.g computers or driving)

Question 17

True or False: T spine mobility affects C spine mobility

Answer 17

True, upper t spine mobility restrictions can cause C spine restrictions as well

Question 18

True or False: Thoracic flexion capabilities are needed to reach full end range shoulder flexion

Answer 18

False, thoracic extension is needed not flexion

Question 19

True or False:The thoracic spine normally becomes more stiff as you go down the spine

Answer 19

True

Question 20

What motions of the vertebra are caused by PA mobilization?

Answer 20

Anterior translation and posterior rotation