prashant gmc cvj

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Post on 07-May-2015



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CVJ is one of the most complex segment for radiologists,,,,, lets see it in an easy way



2. CRANIOVERTEBRAL JUNCTIONThe craniovertebral junction(CVJ) is a collective term thatrefers to the occiput, atlas, axis, and supporting ligaments.It is a transition zone b/w a mobile cranium & relatively rigidspinal column.It encloses the soft tissue structures of the cervico medullaryjunction (medulla, spinal cord, and lower cranial nerves). 3. EMBRYOLOGY & DEVELOPMENT OF THE CVJDevelopment of the cartilaginous cranium & the adjacent structures begins during theearly weeks of intrauterine life.2ndGestational week:Mesoderm cells condense in the midline to form notochordal process.3rdGestational week:-notochordal process invaginates in b/w ecto& endoderm to form notochord.-dorsal ectoderm thickens to form neural groove which folds, fuses, & becomes neuraltube.Between 3rd& 5thweek:-part of mesoderm which lies on either side of notochord (Paraxial mesoderm) givesrise to somites(Segmentation).-total 42 somitesform at 4thweek.-ventromedial portion of somite is k/a sclerotome which forms the vertebral bodies.-each sclerotome differentiates into a cranial, loosely arranged portion and a caudalcompact portion by a fissure k/a Fissure of von Ebner(Re-segmentation). 4. Each sclerotome differentiates into a cranial, loosely arranged portion ( 1) and a caudal compact portion (2). 5. Notochord disappears at the vertebral bodies, but persist as nucleus pulposus at disc.Out of 4 occipital sclerotomes the first 2 form basiocciput, the 3rd Jugulartubercles and the 4th (Proatlas) form parts of foramen magnum, atlas andaxis.The pro atlas (1) is derived from the cranial portion of the embryonic fourth occipitalsclerotome. Its principal derivatives are the occipital condyles, the dorsalcranial articular facets of the atlas, and the tip of the odontoid.The primitive atlas(2) is derived from the caudal portion of the fourth occipital and the cranial portionof the first cervical sclerotomes. Its principal derivatives are the neural arches andlateral masses of the atlas and the remainder of the odontoid process of the axis.The primitive axis (3) is derived from the caudal portion of the first cervicalsclerotome and the cranial portion of the second. Its principal derivatives arethe body and neural arch of the axis and the C2-3 cervical disk. 6. OSSIFICATION CENTRESOCCIPUT & BASIOCCIPUT:2 occipital squamous portions 2 centresBasiocciput(clivus) -1 centre2 Jugular tubercles 2 centres2 Occipital condyles2 centresATLAS: ossifies from 3 centresEach half of post. Arch with lateral mass unites at 3 4 years.Anterior arch unites with lateral mass at 6 8 years.AXIS: ossifies from 5 primary & 2 secondary centres.2 Neural arches 2 centres appear at 7 8 wkBody of axis 1 centre appear at 4 5 monthsBody of dens 2 centres appear at 6 7 months4 pieces (at birth) unite at 3 6 yearsTip of odontoid appears at 3 6 years, unites with the body of odontoid at 12 years. 7. EMBRYOLOGY & DEVELOPMENT OF THE CVJATLAS: no vertebral body & no IV disc.-major portion formed by first spinal sclerotome.-trasitional vertebra as centrum of sclerotome is separated to fuse with the axis bodyforming the odontoid process.-hypocentrum of 1st spinal sclerotome forms the anterior arch of the atlas.-neural arch of the first spinal sclerotome forms the inferior portion of the posterior archof atlasAXIS: develops from 2nd spinal sclerotome.-hypocentrum of 2nd spinal sclerotome disappears during embryogenesis.-centrum forms the body of the axis vertebra & neural arch develops into the facets &the posterior arch of the axis.-At birth odontoid base is separate from the body of axis by a cartilage which persistsuntil the age of 8, later the center gets ossified or may remain separate as Os-odontoidium.-The apical segment is not ossified until 3 years of age, at 12 years if fuses withodontoid to form normal odontoid failure leads to Os terminale.. 8. ANATOMY OF CVJ(ARTICULAR)Upper surfaces of C1 lateralmasses are concave which fit intothe ball & socket configuration.4 synovial joints b/w atlas & axis2 median Pivot variety2 lateral Plane varietyEach joint has its own capsule &synovial cavity. 9. ANATOMY OF CVJ(LIGAMENTOUS)ATLANTO-OCCIPITAL LIGAMENTS:A) Anterior Atlanto-occipital Membrane ----about 2 cm wideLigament is continuous caudally with the anteriorA-A ligament & through it to the ALL of the spinalcolumn.It acts as a tension band that stretches duringextension, serving as a secondary stabilizer againstthis motion.B) POSTERIOR ATLANTO-OCCIPITALMEMBRANE:A less strong ligament containing no significantelastic tissue.Ligament invests itself on either side to form acanal through which the vertebral artery,accompanying veins, & the first cranial nerve pass.C) LATERAL ATLANTO-OCCIPITALLIGAMENTS:-ascending lig which reinforce the A-O jointcapsules. 10. ATLANTO AXIAL LIGAMENTS:Anterior A-A ligament,Posterior A-A ligamentTransverse ligament of the atlas:-thick, strong & about 6mm in height.-Caudal crus & Rostral crus(Fasciculilongitudinales) fibres joined withtransverse ligament on its dorsal aspectto form Cruciate ligament of atlas.TAL effectively limits anteriortranslation and flexion of the atlantoaxial joint.An accessory band ventral to theascending crus attaching to the apex ofthe odontoid process is termed Gerbersligament. 11. A) TECTORIAL MEMBRANE:Dorsal to the cruciate ligamentAttached to the dorsal surface of the C3vertebra, axis body & to the body of dens.Rostral extension of the PLL of thevertebral column.Essential for limiting flexion.The accessory bands of the ligamentpassing to the lateral capsule of the A-Ajoints --Arnolds ligamentB) ALAR LIGAMENTS:2 strong cords that attach to the dorsal lateralbody of the dens .Extend laterally & rostrally.Ventral & cranial to the transverse lig. allow ananterior shift of C1 from 3 to 5 mm.Limit the head atlas rotatory movement on theodontoid axisStrengthen the A-O capsule.C) APICAL LIGAMENT:.No mechanical significance.AXIS OCCIPITAL LIGAMENTS: 12. ANATOMY OF CVJ (MUSCLES)Muscles have only a minor role related to CVJ stabilization & do notlimit the movements of the joints.Their principal function is one of initiating & maintaining movement atthe CVJ.Neural structures related to CVJ are Caudal portion of brainstem (Medulla)CerebellumFourth ventricleRostral part of spinal cordLower cranial & upper cervical nerves 13. ANATOMY OF CVJ (NEURAL)In cerebellum, only thetonsils, biventral lobules & the lowerpart of the vermis(nodule, uvula &pyramid) are related to CVJ.Biventral lobule is located above thelateral part of FM & the tonsils lieabove the posterior edge.CRANIAL NERVES :Lower four cranial N. are closelyrelated to CVJ.9th & 10th cranial N arise from themedulla in the groove b/w the inferiorolivary nucleus & the inferiorcerebellar peduncle.The accessory N is the onlycranial N that passes throughthe FM. 14. SPINAL NERVE ROOTS:The C1, C2, and C3 nerves, distal to the ganglion, divide into dorsal andventral rami.The first cervical nerve located just below the foramen magnum.The dorsal rami divide into medial and lateral branches that supply theskin and muscles of the posterior region of the neck.. 15. ANATOMY OF CVJ (ARTERIAL)The major arteries related to CVJ arevertebral, postero inferior cerebellar arteries(PICA), and the meningeal branches of thevertebral, and external and internal carotidarteries.VERTEBRAL ARTERY arises from the upperposterior part of the first segment of thesubclavian artery in the neck.Each artery is divided into intradural andextradural parts.The branches arising from the vertebralartery in the region of the FM are the posteriorspinal, anterior spinal, PICA, and anterior andposterior meningeal arteries.The PICA is the largest branch of the vertebralartery 16. Brain stem arteries - anteriorview1. Posterior cerebral artery2. Superior cerebellar artery3. Pontine branches of thebasilar artery4. Anterior inferior cerebellarartery5. Internal auditory artery6. Vertebral artery7. Posterior inferior cerebellarartery8. Anterior spinal artery9. Basilar arteryThe tonsillo medullary PICA segment, which forms the caudal looprelated to the lower part of the tonsil, is most intimately related to theforamen magnum. 17. ANATOMY OF CVJ (LYMPHATICS)The lymphatic drainage of the O-A-A joints is primarily into theretropharyngeal LN & then into the deep cervical chain.These LNs also drain the nasopharynx & hence retrograde infection mayaffect the synovial lining of the CVJ complex with resultant neckstiffness & instability.ANATOMY OF CVJ (VENOUS)The venous structures in the region of the FM are divided into threegroups:-Extradural veins(extraspinal & intraspinal part)-Intradural(neural) veins, &-Dural venous sinuses( superior petrosal, marginal & occipital) The three groups anastomose through bridging and emissary veins 18. KINETIC ANATOMY OF CVJ CVJ units are unique with respect to the rest of the spine in that theydo not bear weight through disks, but rather through synovial joints linedwith hyaline cartilage, thus exhibit significantly more movement thanany other spinal level. ROTATION : when movement occurs about an axis. TRANSLATION: when movement occurs along an axis. 19. ATLANTO-OCCIPITALJOINTS :The C1 lateral masses contain theoccipital condyles in a cup-likefashion.Joint is biaxial havingmovements only around thetransverse & A-P axes.2 types of movement permitted areforward or backward bending & aslight lateral tilting motion to eitherside.These joints do not permit rotation. 20. ATLANTOAXIAL JOINTS : Consists of 2 lateral zygapophyseal & 2median odontoid joints (pivot joint). Rotation of atlas occurs around theodontoid. The superior facet of the axis is convex& the inferior facet of the atlas is eitherhorizontal or slightly convex.So the facets slide forward & backwardon each other with rota