C1 (Quiz 2/ Test 2) Flashcards
What is the most atypical vertebra of the spine?
C1
Why is C1 atypical?
-no body
-no SP
-no pre/post-zygopophyses
-has lateral masses
-has anterior and posterior arches
-it is a pentagonal ring embedded within a diamond shape
What is the main bulk of C1?
lateral masses
What structure on C1 supports and transmits weight of the head onto C2?
lateral masses
What are the lateral masses homologous to?
articular pillars
The superior articular surfaces of C1 cover the entire top of…
each lateral mass
What do the superior articular surfaces of C1 articulate with?
occipital condyles above
The superior articular surfaces of C1 match what other surfaces?
condylar surfaces
What shape are the superior articular surfaces of C1?
kidney shaped, smooth, and concave (large axes converge anteriorly)
What direction do the superior articular surfaces of C1 face?
test q
superomedially
The superior articular surfaces of C1 may show a sulcus. What is this the result of?
subcortical vessel
The inferior articular surfaces of C1 cover the entire bottom of….
each lateral mass
What do the inferior articular surfaces of C1 articulate with?
C2 superior articular surfaces
What shape are the inferior articular surfaces of C1?
round/ oval (long axes converge anteriorly)
What direction do the inferior articular surfaces of C1 face?
test q
inferomedially (from a wedge with the superior articular surfaces)
What are the inferior articular surfaces of C1 covered with?
thick cartilage (actual joint surfaces are convex)
What tubercle is found on the lateral masses? Where does it project?
medial atlantal tubercle
-distinct round bump on the medial surface of each lateral mass
-projects into the neural foramen
What is homologous to the medial atlantal tubercles on the lateral masses of C1?
test q
the medial condylar tubercle
What part of the lateral masses on C1 is an attachment for the transverse ligament?
medial atlantal tubercle
What is the only typical portion of C1?
TPs
Which cervical vertebra has the longest TPs?
C1
What are the 3 parts of C1 TPs?
1) anterior false costo
2) posterior true
3) distal transverse tubercle
Where do the anterior false costo part of TPs of C1 project?
Postero-infero laterally
Where do the posterior true parts of the TPs of C1 project?
antero-supero laterally
What 2 parts of the TPs of C1 fuse distally? Where do they end/what is it called?
Anterior and posterior parts of TPs of C1 fuse distally
They end in a large knobby transverse tubercle
What is the biggest hole in C1 called? What flows through it?
Foramina transversaria
-vertebral arteries slide in/out during rotation
-blood flow may be temporarily occluded ipsilaterally
-prominent lever arms for lateral flexion and rotation
What structure joins the lateral masses of C1 anteromedially?
Anterior arch (straight or slightly convex bony bridge)
What is the anterior arch of C1 homologous to?
Fused pedicles (C1 minus body)
What structure on C1 is the attachment for the longus cervicus muscle and anterior ligaments?
Test q
Anterior tubercle (low rounded bump on the anterior midline)
What is the fovea dentalis of C1?
-concave, oval articular facet
-smooth, raised margins
-posterior median aspect of the anterior arch
What does the fovea dentalis of C1 articulate with?
The anterior dens
What structure on C1 joins the lateral masses posteromedially?
Posterior arch
Is the posterior arch considered one structure or two?
1 structure with L/R sides
What is the posterior arch of C1 homologous to?
Test q
The laminae
What is the posterior tubercle of C1?
-low rounded bump on the posterior midline
-rudimentary SP
-often slightly bifid
What are the superior vertebral/neural grooves (L/R) of C1? What do they help form?
-shallow/flat superior depressions
-just behind lateral masses
-help form the 1st IVFs
What enters and exits the superior vertebral/neural grooves (L/R) of C1?
-vertebral arteries enter anteriorly
-C1 spinal nerves exit posteriorly
What is the inferior vertebral/neural notches (L/R) of C1? What do they form?
-deeper inferior depression
-just behind lateral masses
-help form 2nd IVFs (C2 spinal nerve exits here)
What is the neural foramen? What are its 2 parts and what are the contents in each part?
-looks like foramen magnum
-larger posterior neural portion contains the spinal cord
-smaller anterior odontoid portion contains the dens
