The cruciate ligament of the atlas (cruciate may substitute for cruciform) is a

ligament A ligament is the fibrous connective tissue that connects bones to other bones. It is also known as ''articular ligament'', ''articular larua'', ''fibrous ligament'', or ''true ligament''. Other ligaments in the body include the: * Peritoneal li ...

in the

neck The neck is the part of the body on many vertebrates that connects the head with the torso. The neck supports the weight of the head and protects the nerves that carry sensory and motor information from the brain down to the rest of the body. In ...

. It forms part of the

atlanto-axial joint The atlanto-axial joint is a joint in the upper part of the neck between the atlas bone and the axis bone, which are the first and second cervical vertebrae. It is a pivot joint. Structure The atlanto-axial joint is a joint between the atlas bo ...

. The ligament is named after its cross shape. It consists of

transverse Transverse may refer to: *Transverse engine, an engine in which the crankshaft is oriented side-to-side relative to the wheels of the vehicle *Transverse flute, a flute that is held horizontally * Transverse force (or ''Euler force''), the tangen ...

and longitudinal components. The posterior longitudinal band may be absent in some people. The cruciate ligament of the atlas prevents abnormal movement of the atlanto-axial joint. It may be torn, such as by

fractures Fracture is the separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the solid. If a displa ...

of the atlas bone. Anatomy of the Neck Sagittal Color MRI

Structure

The cruciate ligament of the atlas consists of the transverse ligament of the atlas, a superior longitudinal band, and an inferior longitudinal band. The superior longitudinal band connects the transverse ligament to the anterior side of the

foramen magnum The foramen magnum ( la, great hole) is a large, oval-shaped opening in the occipital bone of the skull. It is one of the several oval or circular openings (foramina) in the base of the skull. The spinal cord, an extension of the medulla oblon ...

(near the basilar part) in the

occipital bone The occipital bone () is a neurocranium, cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobe ...

of the skull. The inferior longitudinal band connects the transverse ligament to the body of the

axis bone In anatomy, the axis (from Latin ''axis'', "axle") or epistropheus is the second cervical vertebra (C2) of the spine, immediately inferior to the atlas, upon which the head rests. The axis' defining feature is its strong odontoid process (bon ...

(C2). Gerber's ligament runs deep to the superior band of the cruciate ligament of the atlas.

Variation

The inferior longitudinal band may be absent in some people. The rest of the ligament is always present.

Function

The cruciate ligament of the atlas prevents abnormal movements of the

. The longitudinal bands prevent

hyperflexion Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relative ...

and hyperextension of the

, and hold the transverse ligament of the atlas in a normal position.

Clinical significance

Any part of the cruciate ligament of the atlas may tear, which is a significant injury. This may be caused by

of the atlas bone. Ligament tears may be imaged with radiography, a

CT scan A computed tomography scan (CT scan; formerly called computed axial tomography scan or CAT scan) is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers ...

, or

magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio wave ...

Ossification

Very rarely, the cruciate ligament of the atlas may

ossify Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in th ...

. This may lead to

cervical myelopathy Myelopathy describes any neurologic deficit related to the spinal cord. The most common form of myelopathy in humans, '' cervical spondylotic myelopathy (CSM)'', also called ''degenerative cervical myelopathy'', results from narrowing of the spina ...

, a deficit in the spinal cord.

Etymology

The terms "cruciform" and "cruciate" refer to the cross shape of the

. Both terms are frequently used, although the term "cruciate" may be confusing due to confusion with the anterior cruciate ligament and the posterior cruciate ligament of the

knee In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest joint in the hu ...

References

{{Authority control Ligaments of the head and neck Bones of the vertebral column