Cervical spine: anatomy, biomechanics and pathomechanics

This slideshow describes about the anatomy, biomechanics and pathomechanics regarding to cervical joints

1. RADHIKA CHINTAMANI
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2. CONTENTS
•ANATOMY
•BIOMECHANICS
•PATHOMECHANICS
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3. CERVICAL SPINE ANATOMY
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•Cervical vertebral column
consists of 7 vertebrae's of
which first two are distinct
from the rest.
•Two distinct regions:
A.Upper cervical spine:
Craniovertebral/suboccipital
region, atlas and axis
B.Lower Cervical vertebral
column

4. Craniovertebral Vertebrae
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1.Atlas:
•Functions to cradle the occiput
and to transmit forces from head
to the cervical spine.
•Distinctive from other Cervical
vertebral column as it has two
large lateral masses vertically
aligned below the occipital
condyles
•The atlantal sockets typically
exhibit right–left asymmetry.
•Lack of Body
2. Axis: Has bifid spinous process
and Provides axial rotation of the
head and atlas

5. Lower Column C3-C7 Vertebrae
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3. Lower 5 Cx vertebrae:
•The vertebrae exhibit features
that reflect these load-bearing,
stability, and mobility functions.
•This may be considered as
triangular column consisting of
anterior pillar composed of the
vertebral bodies and two
posterior column consisting of
right and left articular pillars of
the articulating facets.

6. Lower Column C3-C7 Vertebrae
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•Posteriorly, the articular processes bear the superior and inferior
articular facets. Generally, the superior facets are directed
superiorly and posteriorly, while the inferior facets are directed
anteriorly and inferiorly.
•In the upright posture, the superior facet lies between the
transverse and frontal planes, and as a consequence, it helps
support the weight of the head and stabilizes the vertebra above
against forward translation.
•The superior articular facets change from a posteromedial
orientation at the C2/C3 level to posterolateral orientation at
C7/T1. The transition typically occurs at the C5/C6 level

7. C7 Vertebrae
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•The unique morphology exhibited by
the seventh cervical vertebra
reflects its load-bearing function. It
is the point where the neck is
cantilevered off the more rigid Tx
spine.
•It provides more stability and guards
against forward translation.

8. Joints of the Cx Spine
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1.Craniovertebral Joints:
•The two atlanto-occipital joints are found between the superior
concave sockets of the atlas and the occipital condyles of the skull.
2. Atlantoaxial joints: Consists of 3 synovial joints:
A.Right and left atlantoaxial joint
B.Median Atlantoaxial joint
•Together these joints allow axial rotation of the head and atlas
where the centrally placed odontoid process acts as a pivot around
which the anterior arch of the atlas spins. This movement is
accommodated anteriorly by the median atlantoaxial joint and
inferiorly by the lateral atlantoaxial joints.

9. Ligaments of Craniovertebral joints
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1.Transverse Ligament: resists forward translation of atlas relative to
axis and is integral to the stability of atlantoaxial joints.
2.Alar Ligament: the orientation of the alar ligaments is closer to
being horizontal, running from the lateral aspect of the odontoid
process to the margins of the foramen magnum. Critical
importance in rotation of the head and atlas on axis.
3.Membrane Tectoria/Tectorial Membrane: multidirectional stability
of the upper spine, particularly in upper cervical flexion and axial
rotation
4.Atlanto-Occipital and Atlantoaxial membranes: classified as false
ligaments. Ramsey sectioned these posterior membranes and
found some elastic fibers, although fewer than typically seen in
the ligamentum flavum and suggested that these structures
should be considered being “in series” with the ligamentum
flavum.
5.Apical Ligament: small in size, missing in 20% people. No known
biomechanical importance.

10. Joints of lower Cx spine
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•The vertebral bodies below C2 are joined via intervertebral
discs.
•In the adult, the anulus fibrosus in the cervical region is a
discontinuous structure surrounding a fibrocartilaginous core,
instead of being a fibrous ring enclosing a gelatinous nucleus
pulposus like the anulus fibrosus in the lumbar region.
•The adult cervical nucleus is characterized by fibrocartilage,
with no gelatinous component.
•Facet joints: parallel to frontal plane and 45 degree to
transverse plane.

11. Ligaments of Lower Cx joints
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1.Ligamentum flavum: thinner in neck, serves to provide a
smooth elastic posterior wall to spinal canal thereby
protecting spinal cord against any buckling.
2.Ligamentum Nuchae: midline structure helpful in control of
head posture.

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ANTERIOR LONGITUDINAL LIGAMENT POSTERIOR LONGITUDINALLIGAMENT

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–Ligamentum flavum
LIGAMENTUM FLAVUM INTERTRANSVERSE LIGAMENTS

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INTERSPINOUS LIGAMENTS LIGAMENTUM NUCHAE

15. ROM
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Motion ROM
Flexion 0-45/500
Extension 0- 50/60
Lateral Flexion 0-40/50
Rotation 0-70/80
Combined Movements
Upper Cx
Lower Cx

16. COUPLED MOVEMENTS
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Lateral flexion with rotation

17. MUSCLES OF CERVICAL SPINE
•FLEXORS- longus colli, sternomastoid, scalenus anterior, longus capitis,
rectus capitis anterior
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18. •EXTENSORS- levator
scapulae, splenius cervicis,
trapezius, splenius capitis,
errector spinae, rectus
capitis posterior major and
minor and superior oblique
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19. •LATERAL FLEXORS- scalenus anterior, medius and
posterior,levator scapulae, sternomastoid, splenius capitis,
trapezius, errector spinae
•ROTATORS – semispinalis cervicis, multifidus, splenius anterior,
splenius cervicis & capitis, sternomastoid, inferior obllique,
rectus capitis posterior, major
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20. BIOMECHANICS OF CERVICAL SPINE
KINEMATICS:
•The cervical spine is designed relatively for a large amount of mobility.
Normally the neck moves 600 times every hour whether are awake or asleep.
•The motions of flexion and extension, lateral flexion and rotation are
permitted in the cervical region. These motions are accompanied by
translations that increase in magnitude from C2 to C7.
•Greatest ROM occurs the middle of the cervical at the level of C5-C6
during flexion and extension
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21. 21
CERVICAL
MOVEMENTS

22. •Cervical motion segment has six degree of freedom, translations in
each plane and rotations in each axis.
•These motion are coupled such that motions around one axis are
consistently associated with motion around another axis.
22A=Side to side
translation in frontal
B=Supero-Inferior
translation
C=Antero-Posterior
translation in sagittal
plane
D=Side to side rotation
in frontal plane
E=Rotation in transverse
plane
F=Antero-Posterior
Rotation in Sagittal
Plane
A=Side to side
translation in frontal
B=Supero-Inferior
translation
C=Antero-Posterior
translation in sagittal
plane
D=Side to side rotation
in frontal plane
E=Rotation in transverse
plane
F=Antero-Posterior
Rotation in Sagittal
Plane

23. KINETICS
•Loads on the cervical spine are produced mainly by the weight of the
head, the activity of the surrounding muscle, the inherent tension of
the adjacent ligament and the application of the external loads.
•Studies confirmed the obvious fact that the physiologic loads on
cervical region are generally lower than those on the thoracic and
lumbar spine.
•These loads are minimal during upright relaxed standing & sitting.
•Rotation & lateral flexion increases the loads moderately.
•During extreme flexion & extension these loads are increased
maximally
•There are two types of loading on cervical spine: Static and Dynamic
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24. Analysis of forces on Cx spine
•Atlanto-occipital joint of an adult bears approximately 1.2times the body
weight of the reaction forces.
•Static Loading: The neutral zone of the cervical spine describes the arc of
motion that is available around the neutral position without passive
resistance to the motion. The neutral zone is the region in which the
stiffness of the cervical spine complex produced by the bones, discs, and
soft tissue is minimal.
•The neutral zone for flexion and extension is approximately 10, for side-
bending less than 10, and approximately 35 for rotation. The midcervical
region (C2–C5) is stiffer and thus less mobile than the upper and lower
cervical regions, and the cervical spine is less stiff than the thoracic and
lumbar spines and uses less muscle force to produce motion.
•Failure of the cervical spine is reported when it is subjected to flexion
moments of approximately 7 Nm in the midcervical region, but a 12-Nm
flexion moment with an additional 2000-N compression load (450 lb) is
reported before failure occurs in the lower cervical region.
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25. STATIC LOADS
•The load on the junction between occipital bone and C1 is lowest
during extreme extension.
•It is highest during extreme flexion but showed only a slight increase
over that produced when the neck was in neutral position.
•The load on the C7 and T1 motion segment was low with the neck in
the neutral position but became even lower when the head was held
upright with the chin tucked in.
•The load increased some what during extreme extension and
substantially during slight flexion. The greatest loads were produced
during extreme flexion.
DYNAMIC LOADS
•Any sudden movement causes high loads on cervical spine
•Eg: whiplash injuries, facetal dislocations, wedge compression etc
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26. PATHOMECHANICS OF MUSCLES
•EXTENSORS OF THE HEAD AND NECK
•This group includes muscles that extend the head on the neck
(atlanto-occipital joint) and muscles that extend the cervical spine.
•Deep Plane:
•The semispinalis plane: contains the semispinalis capitis and
semispinalis cervicis.
•The plane of the splenius and levator scapulae includes the splenius
capitis, splenius cervicIs, levator scapulae, and longissimus capitis.
•The superficial plane is composed of the trapezius.
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27. DEEP PLANE
(Suboccipital Muscle, Transversospinal Muscle)
•Cervicogenic Headache: If this muscle undergoes
tightness it exerts compression of suboccipital
nerve thus leading to the radiating pain from neck
to head. Known as cervicogenic headache.
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28. SEMISPINALIS PLANE
(semispinalis capitis & semispinalis cervicis)
•No known studies-directly address weakness in
these muscles, but it can be hypothesized that
maintenance of upright head posture would be
compromised by weakness of the semispinalis
muscles.
•Because the semispinalis cervicis may stabilize the
axis and potentiate the function of two of the
suboccipital muscles, weakness in the simispinalis
cervicis could affect the ability of these suboccipital
muscles to fine-tune head mevements in response
to stimuli.
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29. SPLENIUS AND LEVATOR SCAPULAE
PLANE
•(splenius capitis and cervicis)
•Splenius Cervicis: Kendall names it as
one of the muscles affected by the
posture of forward head with
slumped, round upper back and
hyperextension of the cervical spine.
In this condition, the splenius capitis
is theoretically shortended, which
contributes to an overall increase in
compression on the posterior
elements of the articular processes
and vertebral bodies.
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30. •LEVATOR SCAPULAE
Clinical Relevance: Neck and
shoulder pain associated with the
levator scapulae due to its
attachment to cervical (transverse
process) and scapulae (superior
angle)
•Jull characterizes the levator
scapulae as one of the muscles in
the neck shoulder girdle region that
becomes overactive with poor
posture such as forward head.
•Subjects with T4 syndrome often
have pain due to Myofascial Trigger
Point situated in Levator scapulae
muscle
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31. •LONGISSIMUS CAPITIS
•Clinical Relevance: Smaller than the semispinalis capitis
and lies closer to the joints (reduced mechanical
advantage), and more laterally placed, so its lateral
flexion moment arm enhances the muscle’s role in
frontal plane stabilization as one of the “guy wires”
arranged around the skull.
•Provides little stabilization in the sagittal plane,
probably because of its lateral position.
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32. •SUPERFICIAL PLANE
(TRAPEZIUS)
-Commonly gets weakned in neurological
conditions because it is innervated by
cranial nerve.
-Paralysis results in an inferiorly sagging
shoulder tip. In addition, the inferior angle
of the scapula protrudes dorsally and
creates a ridge in the skin of the back that
disappears with flexion of the upper
extremity and becomes more pronounced
during glenohumeral abduction.
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33. •FLEXORS OF THE HEAD AND NECK
(STERNOCLEIDOMASTOID)
•TORTICOLLIS: The most common condition involving the
sternocleidomastoid is torticollis. There are two forms of torticollis:
Congenital and Spasmodic.
Congenital : The most common congenital form is the prenatal
development of a fibrous tissue tumor in the sternocleidomastoid,
resulting in fibrosis & shortening of the sternocleidomastoid fibres thus
causing torticollis. (ipsilateral side bending & contralateral rotation)
•Spasmodic torticollis: Is a condition, in which there is involuntary
contraction of the sternocleidomastoid, resulting in repeated or
sustained lateral flexion, rotation, and extension of the head and
neck.
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34. •LONGUS CAPITIS AND
LONGUS COLLI
Forceful hyperextension
movements of the neck
(such as in whiplash injury)
may stretch and tear the
logus colli and capitis,
thereby reducing the ability
of these muscles to provide
a stable base on which the
trapezius muscle can act.
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35. •SCALENE MUSCLES
•SCALENUS ANTICUS SYNDROME: The
narrow triangular opening between the
anterior scalene, the middle scalene,
and their attachments on the first rib
transmits the subclavian artery and
brachial plexus and is a potential
problem site.
 Compression of these structures in this
space can lead to symptoms such as
diminished sensation, weakness, “pins
and needles” paresthesia, and pain.
Patients with this anterior scalene
syndrome, complain of numbness and
tingling in the arm and fingers.
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36. UPPER CROSS SYNDROME
•Involves the following muscle imbalance
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37. •As these changes take place they alter the relative positions of the
head,neck and shoulders
•The occiput and c1 and c2 will hyperextend, with the head being
translated anteriorly.
•Weakness of the deep neck flexors and increased tone in the
suboccipital musculature .
•The lower cervicals down to the 4th thoracic vertebrae will be
posturally stressed.
•Rotation and abduction of the scapulae occurs as the tone in the
upper fixators of the shoulder causes then to become stressed and
shorten,inhibiting the lower fixators, such as serratus anterior and
the lower trapezius. As a result the scapula loses its stability and an
altered direction of the axix of the glenoid fossa evolves, resulting
in humeral instability which involves additional levator
scapulae,upper trapezius and supraspinatus activity to maintain
functional efficiency.
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38. KLIPPEL FEIL SYNDROME:
•Involves congenital failure of
segmentation of cervical
vertebrae.
 Result is multiple fused cervical
segments
 spectrum of deformity from
fusion of 2 vertebrae to
involvement of entire C- spine;
 fusion of C-2 & C-3 is most
common.
Because of this fusion , the cervical
segments below the level of fusion
will be hypermobile to
compensate for the mobility loss
of fused segments.
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39. WHIPLASH INJURIES:
•Flexion extension injuries are the most common injuries of the
cervical spine.
•MECHANISM: these injuries involves an impact that forces the head
into flexion causing disruption of the posterior ligaments.
•These injuries often occur in youth as a consequence of diving into
shallow water & even more frequently in persons of all ages as a
result of vehicle collisions.
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40. CERVICAL DISC DEGENERATION
•Disc degeneration is more common
in the lower cervical region than in
the upper cervical region.
•Many activities in the daily life
require flexion of the head and
neck leading to increased loading
over the cervical spine.
•The loads on the lower cervical
region also are likely to increase in
abnormal head alignments such as
in forward head posture.
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41. JEFFERSON FRACTURE:
•Fracture of Atlas (C1) vertebra is
called as Jefferson #
•Fracture variants: include two and
three part fractures;
•Mechanism: - original description in
1920 noted role of axial compression.
May also be caused by
hyperextension, causing a posterior
arch fracture.
•Associated injuries: - approximately
one third of these fractures are
associated with a axis fracture and
approximately 50% chance that some
other Cervical-spine injury is present;
-
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42. STENOSIS
•Stenosis is narrowing of a passage or opening.
•In the spine, stenosis is any compromise of the space in the spinal
canal (central stenosis, nerve root canal, or lateral stenosis)
•It be congenital or acquired.
•The narrowing may be caused by soft tissue structures such as a
disk protrusion, fibrotic scars, or joint swelling or by bony
narrowing as with spondylitic osteophyte formation or
spondylolisthesis.
•With progression, neurological symptoms develop.Extension
exacerbates the symptoms.
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