Type:
Educational Exhibit
Keywords:
CT, Conventional radiography, Musculoskeletal system, Head and neck, Foetal imaging, Localisation, Developmental disease
Authors:
G. Ilangovan1, R. G. Reddy2; 1Chennai, TA/IN, 2Chennai/IN
DOI:
10.26044/ecr2019/C-0873
Background
Anatomy of CVJ:
Articular anatomy: upper surfaces of C1 lateral masses are cup like or concave which fit in to the ball and socket configuration,
united by articular capsules surrounding the atlanto-occipital joint & by anterior & posterior atlanto-occipital membranes.
Atlas and axis- four synovial joints between atlas and axis
- two median- front and back of dens (pivot variety)
- two lateral-between opposing articular facets(plane variety),
rotation is up to 900 and approximately half occurs at A-A joint
Ligamentous anatomy: principal stabilising ligaments of C1(figure.1)
1.Transverse atlantal ligament
2.Alar ligaments
Secondary stabilising ligaments
1.Apical ligaments
2.Anterior and posterior A-O membranes
3.Tectorial membrane
4.Ligamentum flavum
5.Capsular ligaments
Craniometric landmarks
( figure.2 and3)
Craniometric measurement
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Anatomic landmarks
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Normal values and clinical implications
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Chamberlains line
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Line joining basion to opisthion
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Dens projecting >6mm above it indicates basilar invagination
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Mc Rae line
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Line joining anterior and posterior margins of foramen magnum
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Odontoid tip lying above this line is indicative of type A basilar invagination
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Wecken-Heim clivus base line
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Line drawn along clivus and extending into upper cervical canal,
it should tangent to odontoid
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If it intersects the body of dens anterior craniocervical dislocation is present and vice versa
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Clivus canal angle
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The angle formed by the wecken-Heim line and a line constructed along the posterior surface of the axis body and odontoid process
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Normal is 150-180 if<150 ventral cord compression may occur
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