this is a presentation on atlanto-axial and atlanto-occipital joints. after reading this, most of you will know about atlas and axis, joint type, anatomy of joint, movements allowed by joint and its clinical considerations.

2. INTIKHAB ALAM 58
SAJJAD AHMAD 29

3. CONTENTS
ATLAS AND AXIS
ATLANTO-OCCIPITAL JOINT
o Ligaments
o Movements
o Muscles help in movements
o Clinical aspects
ATLANTO-AXIAL JOINT
o Ligaments
o Movements
o Muscles help in movements
o Clinical aspects
BLOOD SUPPLY AND INNERVATIONS

4. INTIKHAB ALAM 58

5. ATLAS AND AXIS ANATOMY:
 The atlas is the topmost
vertebra and chief
peculiarity of atlas is that it
has no body, it is ring like
and consist of anterior and
posterior arch and two
lateral masses.
 Axis, the 2nd cervical
vertebra has a concave
under side and convex from
side to side. The most
distinctive characteristic of
this bone is strong odontoid
process, the dens.

9. DEFINITION
 The atlanto-occipital
joint (articulation
between the atlas and
the occipital bone)
consists of a pair
of condyloid joints.
 The atlanto-occipital
joints are synovial
socket-type joints; the
sockets are shallow in
infancy and deepen with
age.

10. LIGAMENTS
 The ligaments
connecting the bones
are:
Two articular capsules
Posterior atlanto-occipital
membrane:
extend from anterior
arch of atlas to posterior
margin of foramen
magnum.
Anterior atlanto-occipital
membrane: extend from
anterior arch of atlas to
anterior margin of
foramen magnum.

12. SECONDARY LIGAMENTS
 The ligamenta flava
join laminae of adjacent
vertebral arches.
 The interspinous
ligaments expand to
form the ligamentum
nuchae which inserts
along the posterior
foramen magnum and
external occipital
condyle.

14. MOVEMENTS
 The movements permitted in this joint are:
 flexion and extension in the Sagittal axis,
which give rise to the ordinary forward and
backward nodding of the head.
 slight lateral motion, lateral flexion to one
or other side in the Frontal axis(titling of
head).
 It's where the nodding action of the head
occurs.

17. MUSCLES HELP IN MOVEMENT
o Flexion is produced
mainly by the action of
longi capitis ,rectus
capitis anteriores and
sternocleidomatoid(ante
rior fibers)
o Extension by the rectus
capitis posteriore
major and minor,
the obliquus capitis
superior,
the semispinalis
capitis, splenius capiitis,
longissimus
capitis, sternocleidomas
toideus and upper fibers
of the trapezius

18. MUSCLES HELP IN MOVEMENT
 The recti laterales
are concerned in
the lateral
movement,
assisted by the
trapezius, splenius
capitis,
semispinalis
capitis, and the
sternocleidomasto
ideus of the same
side, all acting
together.

19. CLINICAL ASPECTS
 Headaches can arise from many different sources
including dysfunctional muscles, tears in the
ligaments, misalignment of the vertebral bodies,
injury to cervical facets and degenerative discs.
 The joint bewteen the two structures is susceptible to
traumatic injury and degeneration.
 Excessive flexion could rupture the supraapinous
ligament.
 Posterior atlanto-occipital membrane ossification
cause migraine headaces due to compresion of artery.

20. SAJJAD AHMAD 29

21. DEFINITION:
The joint formed b/w atlas
and axis in the upper part
of the neck.
 Synovial in nature.
 Atlanto-axial joint is of
complicated nature and
consist of three distinct
joints;
 One is found between the
dens of the axis and the
anterior arch of the atlas.
 Two are located between
the lateral masses of the 1st
cervical vertebra and the
superior articular facets of
the 2nd cervical vertebra.

25. LIGAMENTS
The following four ligaments
stabilize these joints:
 Apical ligament: Connects the
dens to the foramen magnum of
the occipital bone.
 Alar ligaments: Connect the
dens to the lateral margins of
the foramen magnum.
 Cruciate ligament: Attaches the
dens to the anterior arch of the
atlas and the body of the axis to
the foramen magnum of the
occipital bone.
 Tectorial membrane: Starts at
the skull and becomes the
posterior longitudinal ligament.

27. ARTICULAR CAPSULE
 The atlanto-axial articular
capsules are thick and
loose, and connect the
margins of the lateral
masses of the atlas with
those of the posterior
articular surfaces of the
axis.
 Each is strengthened at its
posterior and medial part
by an accessory ligament.

28. MOVEMENTS:
 Lateral AAJ Movement:
It is a synovial joint which allows only gliding. The
opposed articular surfaces of the atlas and axis are not
reciprocally curved but are flat; when therefore, the
upper facet glides forward on the lower it also
descends; the fibers of the articular capsule are
relaxed in a vertical direction, and will then permit
movement in an antero-posterior direction.
Medial AAJ Movement:
This joint allows the rotation of the atlas (and, with
it, the skull) upon the axis i.e round the dens. The
extent of rotation being limited by the alar ligaments.

33. INTERSTING FACT
Owl can
rotate its head
upto 270°.
 This rotation
compensate
for their
ooccular
immobility.

35. MUSCLES HELP IN MOVEMENTS:
 The principal muscles by
which these movements
are produced are the
Sternocleidomastoideus
and Semispinalis capitis of
one side, acting with the
Longus capitis, Splenius,
Longissimus capitis,
Rectus capitis posterior
major, and Obliqui capitis
superior and inferior of the
other side.

36. MUSCLES ORIGIN INSERTION MOVEMENTS
obliquus capitis
inferior
spinous process
of the axis
transverse
process of atlas
rotates the
head to the
same side
obliquus capitis
superior
transverse
process of atlas
occipital bone
above inferior
nuchal line
extends the
head, rotates
the head to the
same side
rectus capitis
posterior major
spinous process
of axis
inferior nuchal
line
extends the
head, rotate to
same side
rectus capitis
posterior minor
posterior
tubercle of atlas
inferior nuchal
line medially
extends the
head

38. CLINICAL ASPECTS:
 Death by judicial hanging may
be due to the rupture of the
transverse ligament of atlas or
fracture of the dens of axis. As a
result, the atlas is dislocated
from the axis and compresses the
spinal cord with fatal outcome.
 Fractures of the dens make up
about 40% of axis fractures.
 When the transverse ligaments
of the atlas ruptures the dens is
set free resulting in atlanto-axial
subluxation or incomplete
dislocation of the medial-atlanto
axial joint.

40. CLINICAL ASPECTS:
 Pathological softening of the transverse and
adjacent ligaments usually resulting from
disorders of connective tissue may also cause
atlanto-axial subluxation.
Down syndrome exhibits laxity or agenesis of
the ligament.
 Dislocation owing to transverse ligament
rupture or agenesis is more likely to cause
spinal cord compression than that resulting
from fracture of the dens.

42. CLINICAL ASPECTS:
 Sometimes inflammation in the craniovertebral area
may produce softening of the ligaments of the
craniovertebral joints and cause dislocation of the
atlanto-axial joints.
 Alar ligaments are weaker than the transverse ligament
of the atlas. Consequently combined flexion and
rotation of the head may tear one or both alar
ligaments.
 Although uncommon, atlanto-axial rotation may
compress the C2 spinal nerve. This may be followed by
prolonged severe headaches and excruciating cervico-occipital
pain.

44. BLOOD SUPPLY AND INNERVATIONS

45. INNERVATION:
• AAJ and AOJ nerves are supplied by the C1 and C2
nerves.

46. BLOOD SUPPLY:
 No blood supply, very
dependent certain
physiological factors
for health and
restoration after injury
however vertebral
artery (important
source of brain blood
supply) passes through
cervical vertebrae and it
may supply these areas.

47. Different movements of head

48. POINTS TO BE NOTE
 Bursa: it is a fluid filled sac that helps reduce friction.
 Ligamentum flavumat craniovertebral region has less
elastic fibers, and more collagen fibers for providing
greater stability and called posterior atlanto-axial and
atlanto-occipital membranes.
 Posterior Longitudinal Ligament become tectorial
ligament in the craniovertebral region much broader
and stronger.
 The Anterior Longitudinal Ligament becomes anterior
atlanto-occipital membrane and the anterior
atlantoaxial membrane in the craniovertebral region.

50. TIME OF YOUR ATTENTION

51. Which ligament prevents excessive rotation
of these atlanto-axial joints?
a)Crucite
b)Apical
c)Check
d)Alar
e)Both c and d

52. How many atlanto-axial joints are there?
a)Two
b)Three
c)Four

53. What Is the superior continuation of
posterior longitudenal ligament?
a)Ligamentum flavum
b)Accessory ligament
c)Membrana tectorai
d)Crucite ligamentum
e)Supraspinous ligament

54. What type of movement AAJ and AOJ do
respectively?
a)Flexion ,extention and rotation
b)Gliding and rotation
c)Rotation and flexion,extention
d)Tilting and rotation

55. Which one is rudimentary of notochord?
a)Accessory ligament
b)Crucite ligament
c)Transverse ligament
d)Apical ligament

56. COMMON SITE OF FRACTURE OF AXIS?
a)Posterior arch
b)Anterior arch
c)Spinous process
d)Odontoid process