Biomechanics of the cervical spine. ppt (3)

Cervical Spine Bio-mechanics.

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

2. 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.

3. 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 atypical typical transitional

4. Structure of a typical cervical vertebra Ver tebral 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 extension ut limits lateral flexion

5. Pedicals -c onnects 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.

6. 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

7. 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 giving attachment to scalene muscles. Possess foramen transversarium

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

9. 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

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

11. 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

12. 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 The cartilage lined inferior articular process corresponds to the superior articular process of c3

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

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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.

20. 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 the ligament

21. 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 Limited by those 3 bony pieces Flexion/extension-15 degrees

22. 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

23. 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 streched

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

25. 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

26. 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

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

28. 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 also added to these movements Any movement b/C7 and T1 amounts for mixed rotation and lateral flexion of C7

29. 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

30. 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 AND PUNJABI

31. 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

32. 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 powerful flexors of head and cervical column sternocliedomastoid

33. 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 maintaining the cervical lordosis

34. 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

35. 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 approximation against the anterior ring of the atlas

36. 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 Prevents distraction of C1 on C2

37. Apical ligament s-of the dens connects the axis and occioital bone of the skull

38. Biomechanics of cervical injury WHIPLASH INJURY IS DUE TO HIT FROM BEHIND CAUSING 1 ST 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 FACET JT CAPSULE, I.V DISC AND ALLAR LIG.

39. 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

40. 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.

41. - 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

42. - 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

43. 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.

44. 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 damage.

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

46. 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

47. Thank you. Debanjan Mondal