Atypical Cervical Vertebrae: C1/Atlas Flashcards
What is the name of the first cervical vertebra?
atlas
What muscle attaches to the anterior arch of C1?
longus colli
What ligaments will attach to the anterior arch of C1?
the anterior longitudinal, anterior atlanto-occipital and anterior atlanto-axial ligaments
What is observed on the back of the anterior arch of C1?
the fovea dentis
What is the orientation of the superior articular facet of C1?
backward, upward, medial (BUM)
What are the morphological characteristics of the inferior articular facet of C1?
asymmetrical, slightly concave or flattened
What is the orientation of the inferior articular facet of C1?
backward, medial, downward (BMD)
What muscles attach to the lateral mass of C1?
levator scapula, splenius cervicis, and rectus capitis anterior
What is thought to represent the pedicle at C1?
the anterior arch
What is the name of the rounded elevation on the medial aspect of the lateral mass of C1?
tubercle for transverse atlantal ligament
What is the distance from the posterior tubercle of the posterior arc to the skin in each gender?
males: about fifty milimeters;
females: about thirty-seven milimeters
What attaches to the posterior tubercle of the posterior arch of C1?
rectus capitis posterior minor muscle and ligamentum nuchae
What attaches to the arcuate rim of C1?
the posterior atlanto-occipital ligament
Ossification of the free margin of the posterior atlanto-occipital ligament result in which atypical bone classification?
accessory bone
What is the earliest age of development where ossification of the anterior free margin of the posterior atlanto-occipital ligament was observed?
about age 7 years old
What may be formed by ossification of the anterior free margin of the posterior atlanto-occipital ligament?
a partial ponticulus posticus or complete ponticulus posticus
What other name may be used to identify a ponticulus posticus?
Kimmerie’s anomaly
What names are given to the opening formed by the ponticulus posticus?
arcuate foramen or retroarticular canal
Ponticulus posticus has observed in what ethic populations?
all ethnic populations thus far
What is the general range of incidence of ponticulus posticus in the populations studied?
1%-41%
What is the gender bias now associated with the ponticulus posticus?
female
What is the location of the “zygapophysis” relative to the atlanto-occipital and atlanto-axial intervertebral foramina?
it forms part of the anterior boundary of the intervertebral foramen in both cases
What are the osseus parts of the transverse process of C1?
costal element, posterior tubercle, true transverse process
What muscles attach to the transverse process of C1?
rectus capitis anterior, rectus capitis lateralis, middle scalene, levator scapula, splenius cervicis, obliquus capitis superior, obliquus capitis inferior, intertranversarii muscles
What suboccipital muscles are known to have fascial projections attaching to the spinal dura?
rectus capitis posterior minor,
rectus capitis posterior major,
obliquus capitis inferior
What are the connection between suboccipital muscles and the spinal dura called?
myodural bridges
What are the lateral bridges of the atlas connected to?
the lateral mass and the transverse process of atlas
What opening is identified when a complete lateral bridge is formed?
the retrotransverse foramen
What are the possible contents of the retrotransverse foramen?
the vertebral artery,
a branch from the suboccipital nerve,
and veins communicating with the venous sinuses of the neck
Which of the ponticles (bridges) of atlas is only observed in humans?
lateral bridges
What is observed in the transverse foramen of C1?
vertebral artery,
vertebral venous plexus,
postganglionic sympathetic motor nerves
What is the gender variation for measurements of the transverse diameter of C1?
males: 78 millimeters
females: 72 millimeters
What is the distance from the posterior tubercle of the transverse process of C1 to the skin for each gender?
a little over 30 millimeters for both males and females
What joint classification are observed at C1?
fibrous (amphiarthrosis) syndesmosis joint, synovial (diarthrosis) ellipsoidal joints, synovial pivot (diarthrosis trochoid) joint, and synovial plane (diarthrosis arthrodia) joint
How many synovial joint surfaces are observed on C1?
five
What synovial joint surfaces are observed at C1?
two superior articular facets, two inferior articular facets and the fovea dentis
