||This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations. (January 2013)|
|Bone: Foramen magnum|
|Upper surface of base of the skull. The hole indicated by an arrow is foramen magnum|
|Occipital bone. Inner surface.|
|Gray's||subject #31 129|
In anatomy, the foramen magnum (Latin: "great hole") is a large opening in the occipital bone of the cranium. It is one of the several oval or circular apertures in the base of the skull (the foramina), through which the medulla oblongata (an extension of the spinal cord) enters and exits the skull vault.
Apart from the transmission of the medulla oblongata and its membranes, the foramen magnum transmits the vertebral arteries, the anterior and posterior spinal arteries, the membrana tectoria and alar ligaments.
In humans, the foramen magnum is farther underneath the head than in great apes. Thus, in humans, the neck muscles (including the occipitofrontalis muscle) do not need to be as robust in order to hold the head upright. Comparisons of the position of the foramen magnum in early hominid species are useful to determine how comfortable a particular species was when walking on two limbs (bipedalism) rather than four (quadrupedalism).
|Wikimedia Commons has media related to: Foramen magnum|
- SUNY Figs 22:4b-10
- cranialnerves at The Anatomy Lesson by Wesley Norman (Georgetown University) (XI)
- Roche Lexicon - illustrated navigator, at Elsevier 34257.000-1
|This musculoskeletal system article is a stub. You can help Wikipedia by expanding it.|