foramen magnum


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Related to foramen magnum: jugular foramen

foramen magnum

[fə′rā·mən ′mag·nəm]
(anatomy)
A large oval opening in the occipital bone at the base of the cranium that allows passage of the spinal cord, accessory nerves, and vertebral arteries.
References in periodicals archive ?
In paediatric practice, it is an extremely useful tool for evaluating causes of hydrocephalus and CSF obstruction at the level of the aqueduct, the fourth ventricle, the outlet foramina of the fourth ventricle and the foramen magnum.
Foramen magnum cerebrospinal fluid flow characteristics in children with Chiari I malformation before and after craniocervical decompression.
In type II malformations, the cerebellar vermis, brainstem, and the fourth ventricle extend through the foramen magnum.
Caudal descent of the cerebellar tonsils at least 3-5 mm below the plane of the foramen magnum
The opening of the foramen magnum proceeds laterally in both directions until the occipital condyles are encountered and the posterior fossa defect is approximately 3.
Enlarged sinus grooves run down the occipital bone, from the back of the head to the foramen magnum; branching veins around the foramen magnum are not apparent.
Also, patients with Chiari syndrome, wherein the cerebellar tonsils of the brain become entrapped in the foramen magnum at the base of the skull, can now have their pathology fully visualized for the first time.
Therefore, surgical clipping of the distal right vertebral artery at the level of the foramen magnum was performed.
At the level of the first cervical vertebra (atlas) it winds behind its lateral mass and enters the skull through the foramen magnum (5).
Damadian continued, "Patients with Chiari syndrome, in which the brain, for lack of sufficient connective tissue support, descends into the foramen magnum (opening) at the base of the skull when the patient is upright, require UPRIGHT[TM] MR imaging.
Only the FONAR Upright(TM) Multi-Position(TM) MRI is able to see the entrapment of the upright brain within the foramen magnum.