Thoracic biomechanics Flashcards
rotation is more available in…
The upper and mid thoracic region
As compared to flexion extension and lateral flexion
flexion and extension motion availability increases in
Lower thoracic spine
Due to facet orientation more approximating lumbar vertebra
thoracic movement ranges
flexion 30-40
extension 20-25
rotation 30-35
lateral flexion- 25-30
thoracic flexion
occurs during forward bending and exhalation
anterior rotation and translation of superior vertebrae on inferior vertebrae
Inferior facet slide up and forward on superior facets
thoracic flexion coupled rib motion
superior vertebral body motion causes anterior rotation of the rib head (inferior demifacet attachment)
Anterior portion of the rib moves inferiorly
in lower ribs… they elevate
thoracic extension
Occurs during backward, bending and inhalation
Posterior rotation and translation of the superior vertebrae on the inferior vertebrae
Inferior facet slides down and backwards on superior facet
thoracic extension, coupled rib motion
Superior vertebral body motion causes posterior rotation of the rib head (inferior Demi facet attachment)
Anterior portion of the rib moves superiorly
lower ribs… depression
Thoracic lateral flexion R
lateral flexion in frontal plane, sagittal axis
Type one mechanics
Ipsilateral compression on the closing facets; downward glide
Contralateral distraction, opening facets; upward glide
Rotation to the opposite direction
L ribs- move away from each other (posterior rotating) depressing lower ribs
R ribs- move towards each other (anterior rotating) elevating lower ribs
thoracic rotation R
rotation occurs in a transverse plane around the vertical axis
Type two mechanics
Causes same side sidebending
The rotate to right, sidebend the right
shifting of the vertebral body to the left-hand side
Ribs on the left are flexed
Ribs on the right extending
Primary muscles of respiration
diaphragm
Scalenes
Intercostals
muscles of forced inspiration
Serratus posterior Superior and inferior
Levator costarum
Sternocleidomastoid
Latissimus dorsi
Iliocostalis cervicis and thoracis
Pectoralis minor and major
Quadratus lumborum
Muscles of forced expiration
abdominals
Transverses thoracis
Internal intercostals
upper ribs mechanics
Pump handle movement
Changes AP diameter
Posteriorly means they elevate
Anteriorly means they depress
middle ribs mechanics
Bucket handle movement
Changes AP and transverse diameter
lower ribs mechanics
caliper like movement
changes transverse diameter
Elevation And depression
Three distinct regions of the T spine
Upper- T1-T3 ( functions as part of the lower C spine); more flexion/extension (treated more efficiently with rotational and lateral flexion techniques)
lower- T10-T12 (functions as part of the upper L spine) (favorably treated with rotational or sidebending techniques)
functional T4- T9 ( true T-spine)
The greatest amount of motion tends to be rotational movements
More limitation with flexion extension
Flexion extension techniques tend to work better in a true thoracic spine
two common patterns of clinical present
Pain from loading- load attenuation
Symptoms related to movement restrictions
load attenuation
Compressive loads on thoracic spine, increase caudally from 9% bodyweight at T1 to 47% bodyweight at T12
design is to handle increasing low demand by progressive increase in
Vertebral body height
end plate cross-sectional area
Bone content higher in lower than upper
upper t spine load
76% compressive load transferred through vertebral body disc complex
lower t spine load
greater load transferred through posterior column via the interlocking lamina and facet joints
IVD load
thinner than the C spine and L spine discs
Annulus Fibrosis is stronger
greater ability to resist rotational stress
Disc lesions are more evident
73% of asymptomatic population had some form of disc lesion
upper and mid thoracic discs
Undergo greater deformation and creep
More viscous, mechanical behavior due to structural arrangements of the annular lamellae
L spine load
Compressive loading evenly distributed across surface of the end plate independent of position of the motion segment
t spine load
load distribution across the end plate becomes asymmetric when loaded outside the neutral position
Can explain pain associated with sustained loading postures like on computers, driving
t spine flexion and extension motion accompanied by very little movement in other planes is due to
Symmetrical anterior rotation of the upper ribs constraints couple movements
Rotation and lateral flexion are more complex due to
asymmetrical movement patterns in the spinal motion segments and the ribs
Lateral flexion
ipsilateral anterior rotation and
Contralateral posterior rotation of the upper ribs
upper T spine rotation to the right
posterior rotation of right ribs
Anterior rotation of left ribs
Normal mechanics and motion of the cervical spine and shoulder should be dependent
upon normal mobility of the upper T spine
habitually flexed upper T spine
reduce capacity of muscles to provide cervical thoracic retraction
Anteriorly rotated upper ribs, restrict the range of the C spine extension and rotation due to requirement for movement out of the neutral spinal alignment
Restricted upper rib mobility has signs and symptoms consistent with
Subacromial impingement or thoracic outlet syndrome
in the mid thoracic spine, the anterior elements are subject to high compressive loads because
Of apex of kyphosis
Progressive wedge deformity of vertebral bodies and disc space narrowing are
Quite common
Can lead to hypomobility of mid thoracic motion segments, and ribs
Particularly in rotation and extension
Anatomical variations are common at
The TL junction and need to be considered
Can be gradual or abrupt
PA stiffness of the thoracic spine increases from
Upper to lower
PA applied perpendicular to the spinal curvature causes
anterior translation
And extension
directed towards body eliminates
Extension but induces a longitudinal force of up to half the applied load
