The atlantoaxial joint is of a complicated nature. It consists of no fewer than four distinct joints.
|Latin||Articulatio atlantoaxialis mediana, articulatio atlantoaxialis lateralis|
There are three atlantoaxial joints: one median and two lateral:
The ligaments connecting these bones are:
The atlantoaxial joint in common terminology is actually a composition of three: two lateral and one median atlantoaxial joints. Because of its proximity to the brain stem and importance in stabilization, fracture or injury at this level can be catastrophic. Common trauma and pathologies include (but are not limited to):
The Dens: significant depression on the skull can push the dens into the brainstem, causing death. The dens itself is vulnerable to fracture due to trauma or ossification.
Transverse ligament: Should the transverse ligament of the atlas fail due to trauma or disease, the dens is no longer anchored and can travel up the cervical spine, causing paralysis. If it reaches the medulla death can result. Alar ligaments: stress or trauma can stretch the weaker alar ligaments, causing an increase in range of motion of approximately 30%.
Posterior atlanto-occipital membrane: genetic traits can sometimes result in ossification, turning the groove into a foramen.
The atlantoaxial 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, which is attached below to the body of the axis near the base of the odontoid process, and above to the lateral mass of the atlas near the transverse ligament.
A widening of the atlanto-axial joint, as measured between the posterior surface of the anterior arch of atlas and the front of the odontoid process, indicates an injury to the transverse atlantal ligament. Normally, this atlanto-dental distance is less than 2 mm, sometimes a maximum of 3 mm is accepted in men and 2.5 mm in women.
The anterior atlantoaxial ligament is a strong membrane, fixed, above, to the lower border of the anterior arch of the atlas; below, to the front of the body of the axis.
It is strengthened in the middle line by a rounded cord, which connects the tubercle on the anterior arch of the atlas to the body of the axis, and is a continuation upward of the anterior longitudinal ligament.
The ligament is in relation, in front, with the longi capitis.Anterior sacroiliac ligament
The anterior sacroiliac ligament consists of numerous thin bands, which connect the anterior surface of the lateral part of the sacrum to the margin of the auricular surface of the ilium and to the preauricular sulcus.Atlas joint
Atlas joint may refer to:
Atlanto-occipital jointAxis (anatomy)
In anatomy, the second cervical vertebra (C2) of the spine is named the axis (from Latin axis, "axle") or epistropheus.
By the atlanto-axial joint, it forms the pivot upon which the first cervical vertebra (the atlas), which carries the head, rotates.
The most distinctive characteristic of this bone is the strong odontoid process known as the dens which rises perpendicularly from the upper surface of the body. That peculiar feature gives to the vertebra a rarely used third name: vertebra dentata. In some judicial hangings the odontoid process may break and hit the medulla oblongata, causing death.Costotransverse ligament
A Costotransverse ligament is a short fibrous band that connects a rib with the transverse process of vertebra. They are some of the ligaments that surround the costovertebral joint.Cruciate ligament
Cruciate ligaments (also cruciform ligaments) are pairs of ligaments arranged like a letter X. They occur in several joints of the body, such as the knee joint and the atlanto-axial joint. In a fashion similar to the cords in a toy Jacob's ladder, the crossed ligaments stabilize the joint while allowing a very large range of motion.Cruciate ligament of atlas
The cruciform ligament of atlas (cruciate may substitute for cruciform) is a cruciate ligament in the neck forming part of the atlanto-axial joint. The ligament is named as such because it is in the shape of a cross.
It consists of the transverse ligament of the atlas, along with additional fibers above and below. These fibers are also known as "longitudinal bands".Grisel's syndrome
Grisel’s syndrome is a non-traumatic subluxation of the atlanto-axial joint caused by inflammation of the adjacent tissues. This is a rare disease that usually affects children. Progressive throat and neck pain and neck stiffness can be followed by neurologic symptoms such as pain or numbness radiating to arms (radiculopathies). In extreme cases, the condition can lead to quadriplegia and even death from acute respiratory failure. The condition often follows soft tissue inflammation in the neck such as in cases of upper respiratory tract infections, peritonsillar or retropharyngeal abscesses. Post-operative inflammation after certain procedures such as adenoidectomy can also lead to this condition in susceptible individuals such as those with Down's syndrome.Interarticular sternocostal ligament
The Interarticular sternocostal ligament is a horizontal fibrocartilaginous plate in the center of the second sternocostal joint. It connects the tip of the costal cartilage to the fibrous junction between the manubrium and the body of the sternum, dividing the joint into two parts.Lumbocostal ligament
The Lumbocostal ligament is a fibrous band that crosses from the twelfth rib to the tips of the transverse processes of the first and second lumbar vertebrae.Lumbosacral joint
The lumbosacral joint is a joint of the body, between the last lumbar vertebra and the first sacral segment of the vertebral column. In some ways, calling it a "joint" (singular) is a misnomer, since the lumbosacral junction includes a disc between the lower lumbar vertebral body and the uppermost sacral vertebral body, as well as two lumbosacral facet joints (right and left zygapophysial joints).Obliquus capitis inferior muscle
The obliquus capitis inferior muscle () is the larger of the two oblique muscles of the neck. It arises from the apex of the spinous process of the axis and passes laterally and slightly upward, to be inserted into the lower and back part of the transverse process of the atlas.
It lies deep to the semispinalis capitis and trapezius muscles.
The muscle is responsible for rotation of the head and first cervical vertebra (atlanto-axial joint).
It forms the lower boundary of the suboccipital triangle of the neck.
The naming of this muscle may be confusing, as it is the only capitis (L. "head") muscle that does NOT attach to the cranium.Obturator membrane
The obturator membrane is a thin fibrous sheet, which almost completely closes the obturator foramen.
Its fibers are arranged in interlacing bundles mainly transverse in direction; the uppermost bundle is attached to the obturator tubercles and completes the obturator canal for the passage of the obturator vessels and nerve.
The membrane is attached to the sharp margin of the obturator foramen except at its lower lateral angle, where it is fixed to the pelvic surface of the inferior ramus of the ischium, i. e., within the margin.
Both obturator muscles are connected with this membrane.Posterior atlantoaxial ligament
The posterior atlantoaxial ligament is a broad, thin membrane attached, above, to the lower border of the posterior arch of the atlas; below, to the upper edges of the laminæ of the axis.
It supplies the place of the ligamenta flava, and is in relation, behind, with the Obliqui capitis inferiores.Posterior longitudinal ligament
The posterior longitudinal ligament is situated within the vertebral canal, and extends along the posterior surfaces of the bodies of the vertebrae, from the body of the axis, where it is continuous with the tectorial membrane of atlanto-axial joint, to the sacrum.It is broader above than below, and thicker in the thoracic than in the cervical and lumbar regions. The ligament is more narrow at the vertebral bodies and wider at the intervertebral disc space which is more pronounced than the anterior longitudinal ligament. This is significant in understanding certain pathological conditions of the spine such as the typical location for a spinal disc herniation.
In the situation of the intervertebral fibrocartilages and contiguous margins of the vertebrae, where the ligament is more intimately adherent, it is broad, and in the thoracic and lumbar regions presents a series of dentations with intervening concave margins; but it is narrow and thick over the centers of the bodies, from which it is separated by the basivertebral veins.
This ligament is composed of smooth, shining, longitudinal fibers, denser and more compact than those of the anterior ligament, and consists of superficial layers occupying the interval between three or four vertebræ, and deeper layers which extend between adjacent vertebrae.
It functions to prevent hyperflexion of the vertebral column.Radiate sternocostal ligaments
The Radiate sternocostal ligaments are fibrous bands that cross from the sternal end of the costal cartilage to the ventral part of the sternum.Sternocostal joints
The sternocostal joints also known as sternochondral joints (or costosternal articulations), are synovial plane joints of the costal cartilages of the true ribs with the sternum, with the exception of the first, which is a synchondrosis since the cartilage is directly united with the sternum. The ligaments connecting them are:
Interarticular sternocostal ligament
Radiate sternocostal ligaments
Costoxiphoid ligamentsSupraspinous ligament
The supraspinous ligament, also known as the supraspinal ligament, is a ligament found along the vertebral column.Tectorial membrane of atlanto-axial joint
The tectorial membrane of atlanto-axial joint (occipitoaxial ligaments) is situated within the vertebral canal.
It is a broad, strong band which covers the dens of the axis, and its ligaments, and appears to be a prolongation upward of the posterior longitudinal ligament of the vertebral column.
It is fixed, below, to the posterior surface of the body of the axis, and, expanding as it ascends, is attached to the basilar groove of the occipital bone, in front of the foramen magnum, where it blends with the cranial dura mater.
Its anterior surface is in relation with the transverse ligament of the atlas, and its posterior surface with the dura mater.