- Foramen magnum
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Bone: Foramen magnum 
Occipital bone. Inner surface. Gray's subject #31 129 MeSH Foramen+Magnum 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 spinal accessory nerve, vertebral arteries, the anterior and posterior spinal arteries, the membrana tectoria and alar ligaments.
Contents
Importance
In humans, the foramen magnum is farther underneath the head than in other 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)..
Additional images
Occipital bone. Outer surface.
Base of skull. Inferior surface.
Base of the skull. Upper surface.
Human brain dura mater (reflections)See also
External links
- 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 article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.
Bones of head and neck: Foramina of the skull (and canals, fissures, meati, and hiati) (TA A02.1.00.053–097, GA 2.178–199) Anterior cranial fossa to Orbit: ethmoidal foramina (anterior, posterior)
to Nasal cavity: olfactory foramina (CN-I) · foramen cecumMiddle cranial fossa to Orbit: optic canal (CN-II) · superior orbital fissure (CN-III,IV,V1,VI)
to Pterygopalatine fossa: foramen rotundum (CN-V2) · pterygoid canal
to Infratemporal fossa: foramen ovale (CN-V3) · foramen spinosum/carotid canal
other: foramen lacerum · hiatus for greater petrosal nerve · hiatus for lesser petrosal nerve · sphenoidal emissary foramenPosterior cranial fossa internal auditory meatus/facial canal/stylomastoid foramen (CN-VII,VIII) · jugular foramen (CN-IX,X,XI) · foramen magnum (CN-XI) · hypoglossal canal (CN-XII) · condylar canal · mastoid foramenOrbit to Nasal cavity: nasolacrimal canal
to Face: supraorbital (notch, foramen) · infraorbital (foramen, groove) · zygomatic foramen (-facial, -temporal)
to Pterygopalatine fossa: inferior orbital fissure
other: Inferior orbital fissure · Fossa for lacrimal sacPterygopalatine fossa to Oral cavity: incisive canals · incisive foramen
to Nasal cavity: Foramen vomerinum · Meatus vomerinus · Fissura vomerina · Hiatus vomerinusOther Categories:- Foramina of the skull
- Musculoskeletal system stubs
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