Clivus (anatomy)
Encyclopedia
The clivus is a part of the cranium, a shallow depression behind the dorsum sellæ that slopes obliquely backward. It forms a gradual sloping process at the anterior most portion of the basilar occipital bone
at its junction with the sphenoid bone
. On axial planes, it sits just posterior to the sphenoid sinuses. Just lateral to the clivus bilaterally is the foramen lacerum
which contains the internal carotid artery
, proximal to its anastamosis with the Circle of Willis
. Posterior to the clivus is the basilar artery
. The clivus supports the upper part of the pons
.
Clivus is also used as an abbreviated term for the clivus ocularis which is the sloping inner wall of the retina
as it dips into the foveola
in the macula
of the eye.
, forms a line which, if extended, is known as Wackenheim's clivus line. Wackenheim's clivus line should pass through the dens
of the axis
or be tangential to it.
Occipital bone
The occipital bone, a saucer-shaped membrane bone situated at the back and lower part of the cranium, is trapezoidal in shape and curved on itself...
at its junction with the sphenoid bone
Sphenoid bone
The sphenoid bone is an unpaired bone situated at the base of the skull in front of the temporal bone and basilar part of the occipital bone.The sphenoid bone is one of the seven bones that articulate to form the orbit...
. On axial planes, it sits just posterior to the sphenoid sinuses. Just lateral to the clivus bilaterally is the foramen lacerum
Foramen lacerum
The foramen lacerum is a triangular hole in the base of the skull located at the base of the medial pterygoid plate.-Transit through the foramen lacerum:...
which contains the internal carotid artery
Internal carotid artery
In human anatomy, the internal carotid arteries are two major arteries, one on each side of the head and neck. They arise from the common carotid arteries where these bifurcate into the internal and external carotid artery, and they supply the brain....
, proximal to its anastamosis with the Circle of Willis
Circle of Willis
The Circle of Willis is a circle of arteries that supply blood to the brain...
. Posterior to the clivus is the basilar artery
Basilar artery
In human anatomy, the basilar artery is one of the arteries that supplies the brain with oxygen-rich blood.The two vertebral arteries and the basilar artery are sometimes together called the vertebrobasilar system, which supplies blood to the posterior part of circle of Willis and anastomoses with...
. The clivus supports the upper part of the pons
Pons
The pons is a structure located on the brain stem, named after the Latin word for "bridge" or the 16th-century Italian anatomist and surgeon Costanzo Varolio . It is superior to the medulla oblongata, inferior to the midbrain, and ventral to the cerebellum. In humans and other bipeds this means it...
.
Clivus is also used as an abbreviated term for the clivus ocularis which is the sloping inner wall of the retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
as it dips into the foveola
Foveola
The foveola is located within a region called the macula, a yellowish, cone photo receptor filled portion of the human retina. The foveola is approximately 0.35 mm in diameter and lies in the center of the fovea and contains only cone cells, and a cone-shaped zone of Müller cells...
in the macula
Macula
The macula or macula lutea is an oval-shaped highly pigmented yellow spot near the center of the retina of the human eye. It has a diameter of around 5 mm and is often histologically defined as having two or more layers of ganglion cells...
of the eye.
Relation of the clivus and dens
The clivus is an important landmark for checking for anatomical atlanto-occipital alignment; the clivus, when viewed on a lateral C-spine X-rayX-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
, forms a line which, if extended, is known as Wackenheim's clivus line. Wackenheim's clivus line should pass through the dens
Dens (anatomy)
The dens is a protuberance of the axis . It exhibits a slight constriction or neck, where it joins the main body of the vertebra...
of the axis
Axis (anatomy)
In anatomy, the second cervical vertebra of the spine is named the axis or epistropheus.It forms the pivot upon which the first cervical vertebra , which carries the head, rotates....
or be tangential to it.
