Atypical Cervical Vertebrae: C1/Atlas

Question 1

What is the name of the first cervical vertebra?

Answer 1

Atlas

Question 2

What features are lacking at C1?

Answer 2

Vertebral body
Pedicles
Spinous Process
Intervertebral Disc

Question 3

What muscle attaches to the anterior arch of C1?

Answer 3

Longus Colli

Question 4

What ligaments will attach to the anterior arch of C1?

Answer 4

Anterior longitudinal
Anterior atlanto-occipital
Anterior atlanto-axial

Question 5

What is observed on the back of the anterior arch of C1?

Answer 5

The Fovea Dentis

Question 6

What is the morphology of the superior articular facet of C1?

Answer 6

They are elliptical, closer together in front and often demonstrate an elevation subdividing the facet surface into two separate surfaces.

Question 7

What is the orientation of the superior articular facet of C1?

Answer 7

Backward, upward, medial (BUM)

Question 8

What are the morphological characteristics of the inferior articular facet of C1?

Answer 8

Asymmetrical

Slightly concave or flattened

Question 9

What is the orientation of the inferior articular facet of C1?

Answer 9

Backward, medial, downward (BMD)

Question 10

What muscles attach to the lateral mass of C1?

Answer 10

Levator Scapula
Splenius Cervicis
Rectus Capitis Anterior

Question 11

What is the distance from the posterior tubercle of the posterior arch to the skin in each gender?

Answer 11

Males: about 50mm
Females: about 37mm

Question 12

What attaches to the posterior tubercle of the posterior arch of C1?

Answer 12

Rectus Capitis Posterior Minor

Ligamentum Nuchae

Question 13

What attaches to the arcuate rim of C1?

Answer 13

The posterior atlanto-occipital ligament

Question 14

Ossification of the free margin of the posterior atlanto-occipital ligament results in which atypical bone classification?

Answer 14

Accessory Bone

Question 15

What is the earliest age of development where ossification of the anterior free margin of the posterior atlanto-occipital ligament was observed?

Answer 15

About age 7 years old

Question 16

What may be formed by ossification of the anterior free margin of the posterior atlanto-occipital ligament?

Answer 16

A partial ponticulus posticus or complete ponticulus posticus

Question 17

What other name may be used to identify a ponticulus posticus?

Answer 17

Kimmerle’s Anomaly

Question 18

What names are given to the opening formed by the ponticulus posticus?

Answer 18

Arcuate foramen or Retroarticular canal

Question 19

Ponticulus posticus has observed in what ethnic populations?

Answer 19

All ethnic populations studied thus far

Question 20

What is the general range of incidence of ponticulus posticus in the populations studied?

Answer 20

1%-41%

Question 21

What is the gender bias now associated with ponticulus posticus?

Answer 21

Female

Question 22

What is the location of the “zygapophysis” relative to to the atlanto-occipital and atlanto-axial intervertebral foramina?

Answer 22

It forms part of the anterior boundary of the IVF in both cases.

Question 23

What are the osseous parts of the transverse process of C1?

Answer 23

Costal Element
Posterior Tubercle
True Transverse Process

Question 24

What osseous parts of the transverse process are absent at C1?

Answer 24

Anterior Tubercle

Costotransverse Bar

Question 25

What muscles attach to the transverse process of C1?

Answer 25

``` Rectus Capitis Anterior Rectus Capitis Lateralis Middle Scalene Levator Scapula Splenius Cervicis Obliquus Capitis Superior Obliquus Capitis Inferior Intertransversarii Muscles ```

Question 26

What sub occipital muscles are known to have fascial projections attaching to the spinal dura?

Answer 26

Rectus Capitis Posterior Minor Rectus Capitis Posterior Major Obliquus Capitis Inferior

Question 27

What are the connections between sub occipital muscles and the spinal dura called?

Answer 27

Myodural Bridges

Question 28

What are the lateral bridges of atlas connected to?

Answer 28

The lateral mass and the transverse process of atlas

Question 29

What opening is identified when a complete lateral bridge is formed?

Answer 29

The Retrotransverse foramen

Question 30

What are the possible contents of the retrotransverse foramen?

Answer 30

Vertebral A Branch from sub occipital nerve Veins communicating with the venous sinuses of the neck

Question 31

Which of the ponticles (bridges) of atlas is only observed in humans?

Answer 31

Lateral bridges

Question 32

What synovial joint surfaces are observed at C1?

Answer 32

2 Superior Articular Facets 2 Inferior Articular Facets Fovea Dentis