KINESIOLOGY OF THE SPINE

Cervical Spine Seven vertebrae

– C 1-7

More flexible

Supports the head

Wide range of motion – Rotation to left and right

– Flexion • Up and down

Peripheral nerves – Arms

– Shoulder, Chest and diaphragm

CERVICAL SPINE

cervical region differfrom the thoracic and

lumbar regions in that the cervical region

bears less weight and is generally more

mobile

CERVICAL SPINE

No disks are present at either the atlanto-

occipital or atlantoaxial articulations;

therefore, the weight of the head

(compressive load) must be transferred

directly through the atlanto-occipital joint to

the articular facets of the axis

CERVICAL SPINE

CLOSED PACK position

Neutral or slightly extended position of the

cervical region

Cervical Spine Arthrokinematics

• Flexion and Extension

• Atlanto-occipital joint

• Alar ligament limit the extent of arthrokinematics

FLEXION EXTENSION

Occipital condyles Roll forward Slide backward

roll backward Slide forward

CERVICAL SPINE

Cervical Spine Arthrokinematics

• Full rotation of the craniocervical =65 to 75

degrees

• Half of the axial rotation of the craniocervical

region occurs in the atlantooccipital joint

Cervical Spine Arthrokinematics

• AXIAL Rotation

• Atlanto-axial joint

• Designed for maximal rotation within the horizontal planne

• Articular facet of the atlas slide in a curved path of the articular facet of the axis

• Axis of rotation for the head and atlas provided by the dens

• Limited by contralaterally located alar ligament, aphophyseal joints

Cervical Spine Arthrokinematics

• AXIAL Rotation

• Intracervical aticulation

• Rotation throughout C2 to C7 guided primarily by the onrientation of the facet process within apophyseal joint

• Inferior facet slide posteriorly and inferiorly same sode of rotation

• Inferior facet anteriorly and slightly superiorly on the opposite side

• Rotation is greatest in the more cranial vertebral segment

Cervical Spine

Cervical Spine Arthrokinematics

SPINAL COUPLING between lateral flexion

and axial rotation

• 45 degree of inclination of the articular

facets of C2 to C7

• Lateral flexion and axial rotation in the mid

and low cervical region are mechanically

coupled in an ipsilateral fashion

THORACIC REGION

• typical thoracic vertebra T2 - T9

• vertebral canal narrower

• transverse process has the costal facet to accommodate the tubercle of the rib

• heads of ribs 2-9 articulate with a pair of demifacets at intervertebral junctions (costocorporeal joints)

• atypical thoracic vertebra (T1, T10 , T11, and T12)

• T10 , T11, and T12 - atypical because of the rib attachment

• T1 has a full costal facet

costovertebral joint - articulation between the

head of a typical rib with a pair of costal

facets and the adjacent margin of an

intervertebral disc

Costotransverse joint- articulation between the

articular tubercle of a typical rib to the costal

facet on the transverse process of a

corresponding vertebra.

Ribs 11 and 12 lack costotransverse joints.

Thoracic vertebra are well stabilized by the ribs

and costovertebral and costotransverse

joints.

The arthrokinematics at the apophyseal joints

in the thoracic spine are generally similar to

those described for C2-C7. Flexion between

T5-T6 occurs by a superior and slightly

anterior sliding of the inferior facets of T5 on

the superior facet surfaces of T6. Extension

occurs by a reverse process.

The freedom of axial rotation decreases in the

thoracic spine in a cranial to caudal direction.

In the mid to lower thoracic vertebra , the

apophyseal joints tend to block horizontal

rotation.

Lateral flexion is 25 degrees - Lateral flexion of

T6 on T7 occurs as the inferior facet of T6

slides superiorly on the side contralateral to

the flexion and inferiorly on the side

ipsilateral to the lateral flexion. Ribs drop

slightly on the side of lateral flexion and rise

slightly on the contralateral side.

Coupling is most evident in the upper thoracic

spine where the articular facets possess a

closer orientation to those in the lower

cervical region. The influence of the coupling

decreases and is inconsistent in the middle

and lower thoracic regions.

LUMBAR REGION

• have massive wide bodies

• laminae and pedicles are short and thick

• transverse processes project almost laterally

• short mammillary processes project from the

posterior surfaces of each superior articular

process (for attachment of mulifidi muscles)

• articular facets are near sagittal

SACRUM - triangular bone

during adulthood fused into one

COCCYX

small triangular bone consisting of four fused

vertebrae

base of coccyx joins the apex of the sacrum at

the sacrococygeal joint

typical intervertebral junction has 3

components:

1. the transverse and spinous processes

2. apophyseal joints

3. an interbody joint

the spinous process and transverse

process increase the mechanical

leverage of muscles and ligaments

apophyseal joints or zygapophyseal joints - responsible for guiding intervertebral motion

interbody joints connect an intervertebral disc with a pair of vertebral bodies

intervertebral discs - 25% of the total height of the vertebral column

the vertebral column has 24 pairs of apophyseal joints (plane joints)

horizontal facet surfaces favor axial rotation, whereas vertical facet surfaces block axial rotation

LUMBAR INTERVERTEBRAL DISCS

• consists of a central nucleus pulposus and

and annular fibrosus

• nucleus pulposus is a pulplike gel located in

the mid to posterior part of the disc

• in youth the nucleus pulposus within the

lumbar discs consists of 70-90% water

allwoing shock absorption capable of

dissipating loads across vertebrae

• nucleus pulposus is thickened into a gel by

proteoglycans

• each proteoglycan is an aggregate of many

water-binding glycosaminoglycans

• linked to core proteins. interspersed

throughout the proteoglycans are type II

collagen, elastin fibers and other proteins.

The collagen helps support the proteoglycan

network

annulus fibrosus - consists of 15-25

concentric layers or rings of collagen

fibers

in the annulus, collagen makes up about

50-60% of the dry weight compared to 15-

20% in the nucleus pulposus.

outermost layers of the annulus fibrosus

consists of type I and type II collagen

in contrast to lumbar region, the annulus

fibrosus in the cervical region does not

have complete cervical rings that surround

the nucleus

vertebral endplates - thin cartilaginous caps

of connective tissue that cover the superior

and inferior surfaces of the vertebral bodies

at birth, endplates are very thick accounting for

50% of the height of each intervertebral

space, in the adult 5%

IV disc as a hydrostatic pressure distributor -

shock absorbers

- function as growth plates for the vertebra

Biomechanics responsible

for the shear forces at L5-

S1 and L3-L4

Motions of the spinal column.

(A) Flexion/extension (forward/backward bending).

(B) Lateral flexion (side bending).

(C) Rotation.

(D) Anterior/posterior shear.

(E) Lateral shear.

(F) Distraction/compression.

Source: Therapeutic Exercise : Foundations and Techniques by Carolyn Kisner and Lynn Allen Colby (2007)

Herniated discs and nerve root impingements

are relatively uncommon in the thoracic

spine. This may be due to the low

intervertebral mobility and high stability by

the rib cage.

Thoracic postural abnormalities are common-

prone to the effects of gravity and torsion.

The two most common are kyphosis and

scoliosis.

About 42 degrees of natural kyphosis is

present while standing.

Scheuermann disease (juvenile kyphosis) and

osteoporosis are the 2 most common

conditions associated with kyphosis.

Scheuermann disease (juvenile kyphosis) - a

hereditary condition that starts in

adolescence, of unknown etiology.

- characterized by wedging of the anterior side

of the vertebral bodies

Osteoporosis of the spine - often associated

with excessive thoracic kyphosis in the

elderly.

Compression fractures in osteoporotic thoracic

vertebra eventually lead to reduced height in

the vertebral bodies.

ideal spinal posture- the line-of-force due to

body weight falls slightly to the concave side

of the apex of the normal cervical and

thoracic curvatures.

Vertebra weakened from osteoporosis and

dehydrated intervertebral discs may be

unable to resist the anterior compression

forces.

Over time, the compression forces reduce the

height of the anterior side of the interbody

joint, causing more kyphosis.

SCOLIOSIS- curvature deformity of the

vertebral column characterized by abnormal

curvature in all three planes, most notably in

the frontal and horizontal.

affects the thoracic spine more

structural or functional -

Functional scoliosis - can be corrected by an

active shift in posture, whereas structural

scoliosis is a fixed deformity that cannot be

corrected fully by an active shift in posture.

90% are idiopathic - no apparent cause

LUMBAR REGION

L1 - L4 region

facet surfaces are oriented nearly vertically

with a moderate to strong sagittal bias--

about 25 degrees from the sagittal plane.

Favors sagittal plane movement.

L5 - S1 junction

L5-S1 junction has an interbody joint anteriorly

and a pair of apophyseal joints posteriorly.

Facet surfaces of the L5-S1 apophyseal

joints are usually oriented in a more frontal

plane than those of other lumbar regions.

There is a sharp frontal to sagittal plane

transition from the thoracic to the lumbar

regions which accounts for the tendency of

thoracolumbar hypertension as well as the

high incidence of traumatic paraplegia .

Anterior spondylolisthesis - general term

that describes an anterior slipping or

displacement of one vertebra

- often occurs at L5 - S1

- associated with bilateral fracture or deficit at

the pars articularis (a section of the posterior

lumbar vertebra between the superior and

inferior facets) called spondylolysis which is

the usual cause of spondlolisthesis.

severe spondylolisthesis causes may cause

damage to the cauda equina

increased lumbar lordosis increases the normal

sacrohorizontal angle (N=40 degrees)

thereby increasing the anterior shear force

between L5 and S1

exercises with lumbar hyperextension are CI to

those with spondylolisthesis especially if

unstable or progressive.

the force vector of the lumbar erector spinae

muscle causes an anterior shear force

parallel to the superior body of the sacrum;

the greater the contraction, the greater the

anterior shear especially if it creates more

lordosis

the anteriorly directed shear forces produced

by the lumbar erector spinae occur primarily

at L5-S1 and not the entire lumbar region

LUMBAR SPINE KINEMATICS

• lumbar spine- normal 40 - 50 degrees of

lordosis

• sagittal plane orientation of the facets

• during flexion between L2 and L3, the inferior

articular facets slide superiorly and anteriorly

relative to the superior facets of L3

compression forces from the body weight are

transferred away from the apophyseal joints

(which normally support about 20% of the

total load in erect standing) and toward the

discs and vertebral bodies

flexion of the lumbar spine increases the

intervertebral foramen by 19% and may

relieve pressure symptoms of lumbar spinal

nerve root compression.

however, prolonged lumbar flexion will

compress the anterior disc and if the

posterior annulus fibrosus is weak, the

nucleus pulposus can herniate--herniated

nucleus pulposus (prolapsed disc)

LUMBAR EXTENSION

• increases the lumbar lordosis

• when lumbar extension is combined with full

hip extension, there is anterior pelvic tilting

• hyperextension of the lumbar spine or

hyperlordosis damages the apophyseal joints

and can compress interspinous ligaments

causing LBP

-also causes narrowing of the intervertebral

foramen

• hyperextension of the lumbar spine should

be avoided by those with nerve root

compression caused by stenosed

intervertebral foramen.

• Full extension deforms the nucleus pulposus

anteriorly limiting the posterior migration

reduces pressure within the disc and reduces

the contact pressure between the nuclear

material and neural tissues. --"centralization"

of symptoms: pain felt before in the lower

extremities migrates towards the low back

(nuclear material is pushed forward reducing

contact pressure)

emphasizing lumbar extension exercises and

postures as a way to reduce radiating pain

and radiculopathy from a posterior herniated

nucleus pulposus- popularized by Robin

McKenzie

McKenzie exercises - therapeutic approaches

that emphasize active and passive extension

to relieve symptoms and improve function in

persons with known posterior or posterior

lateral disc herniation

may not be beneficial for all types of low back

pain

A. bending forward normally - 40 degrees from the lumbar spine plus 70 from the hip joint (pelvis on femoral)

B. there is limited hip flexion from tight hamstrings. Greater lumbar and lower thoracic flexion is required.

C. there is limited lumbar mobility and thus, more hip flexion is required

LUMBOPELVIC RHYTHM DURING TRUNK EXTENSION from a bent position:

Extension of the trunk from a flexed position with the knees extended is initiated by extension of the hips, followed by extension of the lumbar spine. The demand on the lumbar extensor muscles increases only after the trunk has been sufficiently raised and the external moment arm, relative to the body weight, has been minimized.

Once standing upright, hip and back muscles are typically inactive as long as the force vector resulting from body weight falls posterior to the hip joint.

An anterior pelvic tilt accentuates lumbar lordosis, a posterior pelvic tilt reduces lumbar lordosis

abnormal lumbopelvic rhythm occurs if there is

restriction at the hip joint and at the lumbar

spine

KINESIOLOGIC CORRELATIONS BETWEEN ANTERIOR PELVIC TILT AND INCREASED LUMBAR LORDOSIS

Active anterior pelvic tilt - caused by contraction of the hip flexors and back extensors.

strengthening and increasing the postural control of these muscles favors a more lordotic posture

maintaining the natural lordotic curvature in the lumbar spine - fundamental principle of McKenzie exercises for persons with a posteriorly herniated nucleus pulposus

exaggerated lumbar lordosis in physiologically undesirable; may be caused by muscle weakness of hip extensor and abdominal muscles in a child with severe muscular dystrophy

- involved in hip flexion contracture with increased passive tension (tightness in the hip flexor muscles)

negative consequences of exaggerated lumbar lordosis-

1. compression of the apophyseal joints

2. increased anterior shear at the lumbosacral angle that might lead to spondylolisthesis

KINESIOLOGIC CORRELATIONS BETWEEN

POSTERIOR PELVIC TILT AND

DECREASED LUMBAR LORDOSIS

active posterior tilt - produced by contraction of

hip extensors and abdominal muscles

strengthening and increasing the postural

control of these muscles to reduce lumbar

lordosis- basis of Williams flexion exercises

HORIZONTAL PLANE KINEMATICS: AXIAL ROTATION

5-7 degrees of horizontal plane rotation occur on

each side for lumbar rotation

clinical measurements often exceed this amount

because of extraneous motion from the hip joint

(pelvis rotating on the femur) and the lower

thoracic region

axial rotation between L1 and L2 to the right

occurs as the left inferior articular facet of L1

approximates or compresses against the left

superior articular facet of L2, Simultaneously,

the right inferior articular facet of L1

separates (distracts) slightly fro the right

superior articular facet of L2.

very limited axial rotation within the lumbar

region; just over 1 degree of axial rotation at

L3-L4

due to a strong sagittal orientation of the lumbar apophyseal joints

the direction of rotation is on the anterior side of any part of the axial skeleton, not the spinous process

in theory, an axial rotation of 3 degrees at any lumbar intervertebral junction would damage the articular facet surfaces and tear the collagen fibers in the annulus fibrosus

the natural resistance to axial rotation provides vertical stability on the lower end of the column; the multifidus and relatively rigid sacroiliac joints reinforce the stability

FRONTAL PLANE KINEMATICS:

LATERAL FLEXION

About 20 degrees of lateral flexion occur on

each side in the lumbar region

Normally, the nucleus pulposus deforms

slightly away from the direction of the

movement toward the convex side of the

bend

SITTING POSTURE AND ITS EFFECTS ON ALIGNMENT WITHIN THE LUMBAR AND CRANIOCERVICAL REGIONS

poor slouched position - pelvis is posteriorly tilted and the lumbar spine relatively flexed (flattened).

increased external moment arm between the vertical line of force of the upper body and lumbar vertebra

- can deform the nucleus pulposus posteriorly especially in the L4-L5, overstretch and weaken it, reducing its ability to block a posteriorly protruding nucleus pulposus

flat posture of the low back is associated with a

protracted position of the craniocervical

region - a forward head posture

the ideal sitting posture includes the natural

lordosis ( and increased anterior pelvic tilt)

extends the lumbar spine

- with chin-in position

SUMMARY

thoracic spine - frontal orientation of facets --

lateral flexion

thoraco-lumbar spi ne - cranial to caudal

direction permits increasing amounts of

flexion and extension at the expense of axial

rotation

the lumbar spine, in combination with flexion

and extension of the hips, forms the pivot

point for sagittal plane motions of the trunk

SACROILIAC JOINTS

• designed for stability and effective transfer of load between the vertebral column and the lower extremities

•

• analogous to the sternoclavicular of the shoulder complex

• injury and pain are not apparent •

• sacrum anchored by the 2 sacroiliac joints is the keystone of the pelvic ring

•

• SI joint located anterior to the posterior sacroiliac spine

during childhood the SI joint is a diarthrodial

joint but starting puberty, it transforms to a

modified synarthrodial joint

SI joint - may develop osteoarthritis often

associated with ankylosing spondylitis

LIGAMENTS

• anterior sacroiliac ligament - thickening of the

anterior and inferior regions of the capsule.

• iliolumbar and anterior sacroiliac reinforce

the anterior side of the SI joint

• interosseous ligament - consists of very

strong and short fibers that fills most of the

gap that exists at the posterior and sperior

margins of the joint

- like syndesmosis

SI joint- innervated by sensory nerves and are

capable of relaying pain

from most of the literature cites dorsal rami of

L5-S3 and less of ventral rami of L5-S2

pain at the ipsilateral lower lumbar and medial

buttock often near the posterior superior iliac

spine

thoracolumbar fascia- plays a role in the mechanical stability of the low back including the SI joint

- has 3 layers: anterior, middle and posterior that compartmentalize the posterior muscles of the lower back

- anchored at the transverse processes of the lumbar vertebra and inferiorly to the iliac crests

-stability is enhanced by attachments of the gluteus maximus and latissimus dorsi

lateral raphe - fused ends of the middle and posterior layers of the thoracolumbar fascia ; this blends with the fascia of the transversus abdominis and with the internal oblique muscles

KINEMATICS OF THE SI JOINT

nutation and counternutation - refer to the

movements of the SI joint at the near sagittal

plane

nutation - means "to nod" ; the relative anterior

tilt of the base (top) of the sacrum relative to

the ilium

counternutation - relative posterior tilt of the

base of the sacrum relative to the ilium

FUNCTIONAL CONSIDERATIONS (SI JOINT)

SI joints perform 2 functions: stress relief mechanism within the pelvic ring and a stable means for load transfer between the axial skeleton and the limbs

SI joint helps disseminate damaging stress at the pelvic ring if it were solid and continuous structure

increased nutation during child birth rotates the lower part of the sacrum posteriorly, thereby increasing the size of the pelvic outlet for the passage of the infant

SI joint pains are common in women during pregnancy due to weight load, hormonal-induced laxity, and increased lumbar lordosis

the close-packed position of the SI joint is full nutation

STABILIZING EFFECT OF GRAVITY

• body weight tends to cause nutation torque, forces from the femoral heads cause counternutation torque --locks the SI joint due to gravity

• - enough for sitting and standing

• - the first line of stability •

• for larger and dynamic loading of the SI joint , muscles and ligaments reinforce the stability on top of the effect caused by gravity

•

• contraction of the erector spinae causes a nutation torque, contraction of the rectus abdominis and biceps femoris causes a counternutation torque

•

• biceps femoris increase the tension at the sacrotuberous ligament

strengthening of the muscles (transversus, internal oblique, gluteus maximus, erector spinae, latissimus dorsi- those attached at the thoracolumbar fascia) add to the stability of the SI joint

the typical intervertebral junction has three elements:

1. spinous and transverse processes for attachment of muscles and ligaments

2. interbody joints for intervertebral adhesion and shock absorption

3. apophyseal joints for guiding the kinematics of each region

SUMMARY

at C1-C2 articular surface - nearly horizontal

throughout the cervical spine - 45 degrees between the horizontal and frontal

the craniocervical region has the greatest potential for 3-dimensional movement of any region in the vertebral column

24 pairs of apophyseal joints at the thoracic region are oriented close to the frontal plane - the expected lateral flexion is limited because of the ribs --relatively rigid required for the mechanics of ventilation and to protect the heart and the lungs

the near sagittal plane orientation of the middle

and upper apophyseal joints within the

lumbar region allows flexion and extension of

the lower end of the vertebral column while

resisting horizontal plane rotation

L5-S1 junction has a frontal plane bias at the

apophyseal joints providing important

restraint to potentially damaging anterior

shear force between the end of the lumbar

spine and the base of the sacrum

RISK FACTORS FOR DEGENERATIVE JOINT

DISEASE

Genetics (primary)

Advanced age

Poor disc nutrition

Occupation (physical work history)

Arthropometrics (body size and proportion)

Long term exposure to total body vibration

CLINICAL CONNECTION

SCOLIOSIS - structural or functional

- abnormal curvatures in all 3 planes, most notably in the frontal and horizontal

most often involves the thoracic spine

functional scoliosis can be corrected by an active shift in posture

structural scoliosis is a fixed deformity that cannot be corrected fully by an active shift in posture

80% of all structural scoliosis are idiopathic,

condition has no apparent cause

progressive idiopathic scoliosis affects

adolescent females 4x more than males

typical scoliosis

scoliosis is described by location, direction, and number of fixed frontal plane curvatures (lateral bends) within the vertebral column

the most common pattern of scoliosis - a single lateral curve with an apex in the T7-T9 region

other patterns may involve a secondary or compensatory curve most often in the thoracolumbar or lumbar regions

the direction of the primary lateral curve is defined by the side of the convexity of the lateral deformity

the magnitude of the lateral curvature is typically measured on x-ray drawing the Cobb angle

with scoliosis, there's asymmetry of the rib cage, ribs on the concave side are pulled together, on the convex side, ribs are spread apart

the degree of torsion (horizontal plane deformity) is measured on an anterior-posterior x-ray by noting the rotated position of the pedicles

fixed contralateral coupling

deformity in structural scoliosis- has a fixed contralateral spinal coupling involving lateral flexion and axial rotation; the spinous processes are rotated in the horizontal plane, toward the side of the concavity ; this explains why the rib hump is at the convex side

factors considered in the treatment of adolescent idiopathic scoliosis:

1. magnitude of the frontal plane curve

2. degree of progression

3. if the child is at a growth spurt

4. cosmetic appearance of the deformity

the younger the child and the greater is the frontal plane curve, the more likely is the progression of scoliosis

objectives of bracing- to prevent a small curve from progressing to a large one

objective of surgery: to stabilize the curve and provide partial correction

thoracic Cobb angle of about 40 degrees or less- strong candidates for bracing

greater than 50 degrees - strong candidates for surgery

between 40 - 50 degrees - gray area as to which treatment is effective

significantly reduced thoracic kyphosis, compromise in pulmonary function and ineffectiveness of bracing - warrant surgery

40 - 50 degrees of natural kyphosis exist while one is standing

hyperkyphosis- may be as a result of trauma and related spinal instability, abnormal growth, and development of vertebra, severe degenerative disease, or marked osteoporosis

a modest increase in thoracic kyphosis with reduction in height is normal part of aging and is usually not debilitating

2 most common conditions associated with progressive thoracic kyphosis:

Scheuermann's kyphosis (juvenile kyphosis) and osteoporosis

Scheuermann's kyphosis (juvenile kyphosis) - most common cause of kyphosis In adolescence

• idopathic , with excessive anterior wedging of thoracic and upper lumbar vertebra

• with a genetic predisposition

• structural scoliosis

OSTEOPOROSIS may lead to thoracic kyphosis seen in elderly women

- a chronic metabolic bone disease affecting post menopausal women

- not a normal part of aging

- may lead to multiple vertebral fractures causing a decrease in height on the anterior side of the bodies (anterior wedging of the bodies)

with significant dehydration of discs present, can lead to more reduction in height

widow's hump- deformity with severe thoracic hyperkyphosis

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