Corpus: Foramen magnum

The term foramen magnum refers to the opening in the area of the posterior fossa through which the medulla oblongata passes and is thus connected to the spinal cord.

3D model of the base of the skull with emergence points, the foramen magnum is labelled No. 10

The foramen magnum is situated in the occipital bone. In addition to the medulla oblongata, the following structures pass through the foramen:

• Spinal root of the accessory nerve (nerve XI)
• Vertebral arteries (left and right)
• Anterior spinal artery
• Posterior spinal arteries (left and right)
• Spinal vein
• Tectorial membrane
• Alar ligaments

Additionally, the foramen magnum marks the transition point where the cranial dura mater becomes the spinal dura mater.