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31
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Gray130png
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Occipital bone Inner surface
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Foramen+Magnum
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A02835232781572434
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In (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
Accessory Nerve (the eleventh of the twelve
Cranial Nerves ), 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 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 (
Bipedality ) rather than four.
