The
Atlanto-occipital joint (
articulation between the atlasIn anatomy, the atlas is the topmost cervical vertebra of the spine.It is named for the Atlas of mythology, because it supports the globe of the head....
and the occipital boneThe occipital bone, a saucer-shaped membrane bone situated at the back and lower part of the cranium, is trapezoid in shape and curved on itself...
) consists of a pair of condyloid joints.
The
Atlanto-occipital joint (
articulation between the atlasIn anatomy, the atlas is the topmost cervical vertebra of the spine.It is named for the Atlas of mythology, because it supports the globe of the head....
and the occipital boneThe occipital bone, a saucer-shaped membrane bone situated at the back and lower part of the cranium, is trapezoid in shape and curved on itself...
) consists of a pair of condyloid joints.
Ligaments
The ligaments connecting the bones are:
- Two Articular capsules
- Posterior atlantoöccipital membrane
The posterior atlantoöccipital membrane , broad but thin, is connected above, to the posterior margin of the foramen magnum; below, to the upper border of the posterior arch of the atlas....
- Anterior atlantoöccipital membrane
The anterior atlantoöccipital membrane is broad and composed of densely woven fibers, which pass between the anterior margin of the foramen magnum above, and the upper border of the anterior arch of the atlas below....
- Lateral atlantoöccipital
Motions
The movements permitted in this joint are:
- (a) flexion
In anatomy, flexion is a position that is made possible by the joint angle decreasing. The skeletal and muscular systems work together to move the joint into a "flexed" position. For example the elbow is flexed when the hand is brought closer to the shoulder...
and extensionExtension is a movement of a joint that results in increased angle between two bones or body surfaces at a joint. Extension usually results in straightening of the bones or body surfaces involved. For example, extension is produced by extending the flexed elbow. Straightening of the arm would...
, which give rise to the ordinary forward and backward nodding of the head.
- (b) slight lateral motion to one or other side.
Flexion is produced mainly by the action of the Longi capitis and Recti capitis anteriores; extension by the Recti capitis posteriores major and minor, the Obliquus superior, the
Semispinalis capitisThe Semispinalis capitis is situated at the upper and back part of the neck, deep to the Splenius, and medial to the Longissimus cervicis and capitis....
, Splenius capitis, Sternocleidomastoideus, and upper fibers of the Trapezius.
The Recti laterales are concerned in the lateral movement, assisted by the Trapezius, Splenius capitis, Semispinalis capitis, and the Sternocleidomastoideus of the same side, all acting together.
Tension-like Headaches
The Atlanto-occipital joint features predominantly in the symptoms of tension-like headaches as a result of prolonged inappropriate
posturePosture or posturing may refer to:In humans* Neutral spine or good posture* Human position* Abnormal posturing, in neurotrauma* Posturography, in neurology* Posture and Occupational HealthIn biology...
from poor ergonomic adaptation.
In such cases, patients typically report cracking of the neck, discomfort when sitting, continuous
migraineMigraine is a neurological syndrome characterized by altered bodily perceptions, severe headaches, and nausea. Physiologically, the migraine headache is a neurological condition more common to women than to men. The word migraine was borrowed from Old French migraigne...
-like headaches, dullness,
dizzinessDizziness refers to an impairment in spatial perception and stability. It is considered imprecise. It can be used to mean vertigo, presyncope, disequilibrium, or for a non-specific feeling such as giddiness or foolishness....
, tingling in the fingers, sensitivity to light and a feeling the head is expanding.