The foramen magnum is the largest opening in the skull. Its main function is to serve as a passage for the structures of the central nervous system through the skull, connecting the brain with the spinal cord.

The foramen magnum appears oval-shaped, with a large anteroposterior diameter. Women and men have slightly different morphologies of the foramen magnum. The sagittal diameter of this opening is greater in males than in females; the same applies to the transverse diameter.

In addition, the anterior and posterior margins of the foramen magnum feature craniometric points (cranial landmarks) - basion and opisthion. The first is a midline point of the anterior border, while the second is a midline point of the posterior border.

Connects: external cranial base to the posterior cranial fossa.

Location: squamous part of the occipital bone.

Transmits: medulla oblongata (the spinal cord transitions into the medulla oblongata at the level of the foramen magnum), meninges, cerebrospinal fluid, vertebral arteries, anterior and posterior spinal arteries, spinal root of the accessory nerve (CN XI), dural veins, apical ligament of the dens (attaches to the anterior margin of the foramen magnum), alar ligaments (attach to the lateral margins of the foramen magnum adjacent to the occipital condyles), and tectorial membrane.