Back Lecture 2 : ATLANTO-OCCIPITAL & ATLANTO-AXIAL JOINTS Flashcards
Atlanto refers to the…
1st cervical vertebra
Where is the Atlantoaxial joint located?
Between the 1st and 2nd cervical vertebrae.
1st and 2nd cervical vertebrae are the atlas and axis, respectively
The atlanto - occipital joint is found between the
Atlas and the occipital bone
The Atlanto-occipital joint is a,,,
synovial joint of ellipsoid variety
The articulating surfaces above and below :
Articulating surfaces
Above: Convex occipital condyles
Below: Concave superior articular facet of atlas
The ligaments of the Atlanto-occipital joint :
- Fibrous capsule
- Anterior atlanto-occipital membrane
- Posterior atlanto-occipital membrane
Which of the 3 ligaments surrounds the atlanto-occipital joint?
The fibrous capsule
Describe the fibrous capsule.
The fibrous capsule is thick postero-laterally and antero-medially
The Anterior atlanto‐occipital membrane is the :
Anterior margin of foramen above to upper border of
anterior arch of atlas below
What is the anterior atlanto-occipital membrane strengthened by?
Anteriorly strengthened by the anterior longitudinal ligament
What is the anterior atlanto-occipital membrane continuous with laterally?
Laterally continuous with the anterior part of capsular
ligament
The Posterior atlanto‐occipital membrane is the :
Posterior margin of foramen magnum above to upper
border of posterior arch of atlas below
What does the infero-lateral free margin arch over?
Infero-lateral free margin arches over the vertebral artery & C1
nerve
What is the posterior atlanto-occipital membrane continuous with laterally?
Laterally continuous with the capsular ligament
The blood supply of the atlanto-occipital joint :
Vertebral artery
The nerve supply of the atlanto-occipital joint :
C1 nerve
The movements of the atlanto-occipital joint :
Ellipsoid joint -biaxial joint)
Flexion / extension (nodding): transverse axis
Lateral flexion: anteroposterior axis
How is the nodding “yes” movement made possible?
The nodding “yes” movement is made possible by the articulation of the occipital condyles rocking in superior articular processes of the atlas. This articulation is called the atlantooccipital joint
The atlanto-axial joint is comprised of 3 joints, namely :
A pair of lateral atlanto-axial joints and a median atlanto-axial joint
The pair of lateral atlanto-axial joints are :
Plane joints
Between inferior facets of the atlas & superior facets of the
axis.
The median atlanto-axial joint is a :
Pivot joint
Between the dens & anterior arch & the transverse ligament
of atlas.
What does the Lateral atlanto-axial joint have?
It has a :
capsule all around it and a ligamentum flavum
What does the lateral atlanto-axial joint form?
The lateral atlanto-axial joint forms the lateral part of the anterior longitudinal ligament
What does the medial atlanto-axial joint have anteriorly?
A Loose capsular ligament anteriorly
What is the posterior part between the dens and transverse ligament continuous with?
Posterior part between dens & transverse ligament is continuous with
the atlanto-occipital joint
What is the main support of the medial atlanto-axial joint?
Main support is the transverse ligament which forms part of the cruciform
ligament
Where does the transverse ligament attach?
The transverse ligament attaches on each side to the medial surface of lateral mass of atlas
What happens in the median plane of transverse ligament?
In the median plane fibers extend upward to basiocciput & downward
to the body of axis to form Cruciform Ligament of atlas
What movements occur at the atlanto-axial joint?
All 3 joints produce rotatory movement around a vertical axis
What is the movement limited by?
Movement is limited by alar ligament
Muscles producing movement are:
Rectus capitis posterior major
Obliquus capitis inferior
Splenius capitis of one side
Sternocleidomastoid of other side
