Cervical Spine Bio-mechanics.

1. Biomechanics of Cervical Spine
Biomechanics of
Cervical Spine
Presented By-Debanjan Mondal
MPT(Musculoskeletal), BPT, CMT,
Ergonomist.

3.  Made up of two anatomically and
functionally distinct segments.
1.Superior segment/suboccipital
segment-
-consist of c1 /atlas and c2/axis
-connected to eachother and
occiput with complex chain of joints.
-having 3 axes and 3 degrees of
freedom.

4. 2.Inferior segment-
-streching from inferior surface
of axis to the superior surface of
T1.
-In total there are 7 cervical
vertebras-
 c1-c2 c3-c6
c7

6. Structure of a typical cervical
vertebra
 Vertebral body-superior plateau
is raised on either sides by 2
buttresses.
 which is called as unciform process.
 It is concave transversely and
convex anteroposteriorly-resembling
a saddle .
 Unciform processes guoides the AP
movements during flexion and

8.  Pedicals-connects the vertebral
body to the transverse process.
 Project posterolaterally.
 Lamina-part of the posterior arch
 Meets in the midline to form the
bifid spinous process
 Projects posteromedially and are
thin and slightly curved.

10.  Spinous process-short slender and
extend horizontally
 The tip is bifurcated
 Face superiorly and medially
 The length of spinous process
decreases from c2-c3
 C3-c5 remains constant
 And undergoes a significant increase
at c7.
 Vertebral foramen –is large and
triangular

11. Transverse process
They are peculiar in
orientation
They are hollowed in to
a gutter AP and they
point AL.
The posteromedial end
of the gutter lines the
intervertebral foramen.
The AL end is bifid

12.  Articular processes-they bear
superior and inferior articular facets.
 Superior facets face superiorly and
medially
 Inferior facets face anteriorly and
laterally

13.  Structure of a atypical cervical vertebra
 Atlas /c1-its ring shaped
 Transverse diameter greater than AP
diameter
 Has two lateral faces oval in shape
running obliquely anteriorly and
medially
 Which bear biconcave superior
articulate facet superiorly and medially
meant to articulate with occipital
condyles

14.  Inferior articular facet –facing
inferiorly and medially
 Convex AP
 Corresponds to superior facet of axis

15.  Anterior arch consist of small
cartilagenous oval shaped articular
facets for the odontoid process of axis
 Posterior arch is initially flattened but
becomes thicker posteriorly to form
posterior tubercle on the midline.
 Transeverse process
 No spinous process
 No intervertebral disc

17. The axis-is atypicsl
 Superior surface of the body carries
centrally the odomtoid process which
acts as a pivot for atlantoodontoid
joint .
 Laterally possess 2 articular facets
facing superior and laterally
 Facets are convex AP and flat
transversely
 Posterior arch consist of narrow
laminae

18.  The cartilage lined inferior articular
process corresponds to the superior
articular process of c3
 Transverse process

19. The atlanto-axial joint complex
 it is a plane synovial joint
 comprises of 3 mechanically linked
joints
 The central joint is the atlanto
odontoid joint
 Two lateral joints-atlanto axial joint

20. Atlantoodointoid joint
 it is synovial trochoid /pivot joint
 Jointsurfaces-anterior articular facet
of odontoid and posterior articular
facet of the anterior arch of the
atlas

21. Movements at atlantoaxial and
atlanto
odontoid joint
 Flexion-point of contact b/w two
convex surface moves forward
 interspace of atlanto odontoid joint
opens superiorly

23. Extention
 Interspace of atlanto odontoid
jointopens inferiorly
 Radiological findingas does not shoe
opening of interspaces
 This is due to transverse ligament and
keeps the anterior arch and odontoid
process in close contact
 During flxn and extn tha inferior
surface of atlas rols and sides over
superior articular surface of axis

25. rotation
 Left to right rotation-
The left lateral mass of
the atlas moves forward
 Right lateral mass
recedes in rotation from
left to right and vice
versa from right to left

27. Movement of atlanto occipital joint
 Formed b/w superior articular
facets of atlas and the occipital
condyles.
 It is an enarthodrial kind of joint
 Gives 3 degrees of freedom
 Axial rotation-about vertical axis
 Flexion/extension-about
transverse axis
 Lateral flexion-about AP axis.

28. flexion
 The occipital condyles
recede on the lateral
masses of the atlas.
 The occipital bone
moves away from the
posterior archof the
atlas
 Limited by tension
developed in the
articular capsules and

29. extension
 Occipital condyles
slides anteriorly on the
lateral masses of the
atlas.
 Occipital bone moves
neatrer to the posterior
arch of the atlas
 Posterior arch of the
atlas and axis are
approximated

30. Lateral flexion
 Movement only occurs b/w c0-c1
and c2-c3
 Left lateral flexion-slipping of
occipital condyles on right of atlas
 Right lateral flexion-vice versa
 Ther is asmall range of motion
 Total ROM-C0-C3=8 degrees
 C0-C1=3 degrees,C2-C3=5
degrees

31. rotation
 When occiput rotates on atlas its
rotation is secondary to rotation of
atlas on axis
 Around vertical axis passing
through the centre of odontoid
 Causes right anterior displacement
of oright occipital condyle on right
lateral mass of the atlas
 Lateral atlanto occipoital ligamenr is

32.  Thus rotation of occiput to left is
associated with –
 Linear displacement of 2-3 mm to the
left
 Lateral flexion to the right

33. Movements at the lower cervical
vertebral column
Extension-ovrlying
vertebral body tilts and
slides posteriorly
 IV space is compressed
posteriorly and opened
wide anteriorly
 Nucleus palposus is driven
slightly anteriorly
 Anterior fibers of annulus
fibrosus is streched

34.  Superiorly articulating facet slides
inferiorly posteriorly and tilts posteriorly
 Limited by anterior longitudinal ligament
and by the impact of the posterior
arches through ligaments
Flexion-upper vertebral body tilts and
slides anteriorly
 Intervertebral space is compressed
anteriorly and opened wide posteriorly
 Nucleus pulposus is driven posteriorly

35.  Posterior fibres of
annulus fiberosus is
streched
 Limited by the tension
developed in the
posterior longitudinal
ligament
 By the capsular
ligament,ligamentum

36. Combined lateral flexion and
rotation-
 Does not occur as pure motions
 Governed by orientation of articular
facets which are oblique inferiorly and
posteriorly
 Rotation is always coupeled with lateral
flexion
 Considering the whole cervical column
from C2-T1 extension component is

37.  Where as any movement b/w C6-C7
also adds up extension component
 Thus three composite movement occurs
in 3 planes-
 Lateral flexion –frontal plane
 Extension-sagittal plane
 Rotation-transverse plane

38. RANGE OF MOTION
JOINT COMBINED FLEXION ONE SIDE ONE SIDE
EXTENSION LAT BENDING AXIAL ROTATION
C2-C3 10 10 3
C3-C4 15 11 7
C4-C5 20 11 7
C5-C6 20 8 7
C6-C7 17 7 6
C7-T1 9 4 2
FROM- WHITE

39. stability
 Cervical region bears less weoight
and are more mobile
 Stability is provided by bony
configuration,muscles,ligamants
Muscles-flexion of head and
neck-
 Depends on anterior muscles of the
neck

40.  They are rectus capitis major, rectus
capitis minor
 Longus cervicis which plays an
important role in straightening the cervical
column and holding it rigid
 Scalene anterior posterior and medius
 Suprahyoid and infrahyoid muscles
helps in supporting the cervical column at
rest
 Thry are located at a distance from
cervical column
 Thus acts via long arm of lever and are

41. Extension of head and neck-
Brought about by posterior neck
muscles
They are0-splenius
cervicis,semispinalis
cervicis,leavator
scapulae,transverso
spinalis,longismus
capiis,spenius capitis,trapezius
These muscles helps in

42.  When contract unilaterally they
produce extension rotation and lateral
flexion on the same side
 Both flexors and extensor group of
muscles are responsible to maintain
cervical column rigid in neutral
position
 Essential in balancing the head and in
supporting weights carried on head

45. ligaments
 Anterior atlnatoaxial
ligament,posterior atlantoaxial
ligament,tectorial
membrane,ligamentum nuchae
 Transverse atlantal ligament-21.9
mm in length
 Also refered as atlantal cruciform
ligament
 Holds dense in closed

47.  Also serves as an articular surface for
dense
 Prevents anterior displacement of C1
on C2
Alar ligaments-arise from axis on
either side of dens
 Approx.1cm in legth
 Are taut in flexion
 Axial rotation of head and neck
tightens both alar ligaments

49. Apical ligaments-of the dens
connects the axis and occioital bone
of the skull

50. Biomechanics of cervical injury
WHIPLASH INJURY IS DUE TO HIT FROM
BEHIND CAUSING 1ST FORCED
EXTENSION OF THE NECK FOLLOWED BY
FOCED FLEXION OF THE NECK.
-2 PHAGES:
1)HYPEREXTENSION OF C5-C6 AND
MILD FLEXION AT C0-C4
2)HYPEREXTENSION OF THE
ENTIRE SPINE
-IF THE HEAD IS IN SLIGHT ROTATION THEN
BEFORE EXTENSION IS FORCED TO
FURTHER ROTATION CAUSING INJURY TO

51.  LOWER CERVICAL FACET RESPOND WITH
SHEAR AND DISTRACTION MECHANISM IN
FRONT AND SHEAR AND COMPRESSION IN
THE BACK.
 DUE TO THE INJURY CAUSE CHANGE IN
PIVOT POINT AT C5-C6 CAUSING JAMMING
OF THE INFERIOR FACET OF C5 AND
SUPERIOR FACET OF C6
 C2-C3 FACET IS THE COMMON SITE FOR
THE PATIENTS WITH HEADACHE(60%) AND
C5-C6 IS THE SITE FOR REFFERED ARM
PAIN

52. Facet joint syndrome
 FACET JOINT IS A SYNOVIAL JOINT AND
BETWEEN TWO FACET JOINT
CARTILAGENOUS DISC IS PRESENT,
DURING FACET LOCKING SYNOVIAL
MEMBRAME AND THE DISC GETS
ENTRAPPED BETWEEN TWO FACET
BONES.
 PAIN IN SIDE FLEXION AND ROTATION TO
THE SAME SIDE AND EXTENSION AS
WELL.
 COUPLING OF LATERAL FLEXION TO
ROTATION IS ALTERED DUE TO FACET
SYNDROME.

54. - CERVICAL SPONDYLOSIS BEGINS WITH
CAPSULAR --RESTRICTION OF THE FACET
JOINTS WITHOUT BONY -CHANGES AND
GRADUALLY PROGRESS TO
CHARACTERISTIC FLATTENING,LIPPING
AND SPURRING OF THE VERTEBRAL BODY.
- ACCELERATED BY INJURY
- BONY STENOSIS OF INTERVERTEBRAL
FORAMEN IS POSSIBLE.
- LOWER CERVICAL SPINE WILL BE
KYPHOTIC
- ACTIVE ROTATION, LATERAL FLEXION TO
PAINFUL SIDE WILL BE RESTRICTED WITH
EXTENSION AS WELL.
- CAPSULAR RESTRICTION IN LOWER
CERVICAL AREA

55. - MOBILITY IN UPPER CERVICAL AREA IS
GENERALLY QUITE GOOD.
- OSTEOPHYTES STABILIZES THE
VERTEBRAL BODY ADJACENT TO THE
DEGENERATIVE DISC AND INCREASE
THE WT. BEARING SURFACE OF
VERTEBRAL END PLATES.
- CERVICAL MYELOGRAM SHOWS
SPONDYLOTIC CHANGE WITH
OSTEOPHYTIC CHANGE

56. Acute cervical injuries
 The most common fracture mechanism in
cervical injuries is hyperflexion.
 Anterior subluxation occurs when the
posterior ligaments rupture.
Since the anterior and middle columns remain
intact, this fracture is stable.
 Simple wedge fracture is the result of a pure
flexion injury. The posterior ligaments remain
intact. Anterior wedging of 3mm or more
suggests fracture. Increased concavity along
with increased density due to bony impaction.
Usualy involves the upper endplate.

57.  Unstable wedge fracture is an unstable
flexion injury due to damage to both the
anterior column (anterior wedge fracture) as
the posterior column (interspinous ligament).
 Unilateral interfacet dislocation is due to
both flexion and rotation.
 Bilateral interfacet dislocation is the result
of extreme flexion. BID is unstable and is
associated with a high incidence of cord
damage.
 Flexion teardrop farcture is the result of
extreme flexion with axial loading. It is unstable
and is associated with a high incidence of cord

59.  Extension injuries
 Hangman's fracture
Traumatic spondylolisthesis of C2.
 Extension teardrop fracture
 Hyperextension in preexisting spondylosis
'Open mouth fracture'

61.  Axial compression injuries
 Jefferson fracture is a burst fracture of the ring of
C1 with lateral displacement of both articular masses
.
 Burst fracture at lower cervical level

62. Thank you.
Debanjan Mondal