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Foramen magnum

 

 
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In anatomy
Anatomy

Anatomy is a branch of biology that is the consideration of the body plan. It is a general term that includes human anatomy, animal anatomy and plant anatomy ....
, in the occipital bone
Occipital bone

The occipital bone, a saucer-shaped membrane bone situated at the back and lower part of the skull, is trapezoid in shape and curved on itself. It is pierced by a large oval aperture, the foramen magnum, through which the cranial cavity communicates with the vertebral canal....
, the foramen magnum (Latin: 'great hole') is one of the several oval or circular apertures in the base of the skull
Skull

The skull is a bone structure found in the head of many animals. The skull supports the structures of the face and protects the head against injury....
 (the foramina
Foramina of skull

The following is a list of holes, or foramen, in the base of the skull and what goes through each of them. Arranged from anterior to posterior:...
), through which the medulla oblongata
Medulla oblongata

The medulla oblongata is the lower portion of the brainstem. It deals with Autonomic nervous system functions, such as breathing and blood pressure....
 (an extension of the spinal cord
Spinal cord

The spinal cord is a long, thin, tubular bundle of neuron and glia that extends from the brain. The brain and spinal cord together make up the central nervous system....
) 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
Vertebral artery

The vertebral arteries are branches of the subclavian artery.The two vertebral arteries and the basilar artery are sometimes together called the vertebrobasilar system, which supplies blood to the posterior part of circle of Willis and anastomoses with blood supplied to the anterior part of the circle of Willis from the carotid arteri...
, the anterior
Anterior spinal artery

In human anatomy, the anterior spinal artery is the blood vessel that supplies the anterior portion of the spinal cord. It arises from branches of the vertebral artery and is supplied by the anterior segmental medullary artery, including the artery of Adamkiewicz, and courses along the anterior aspect of the spinal cord....
 and posterior spinal arteries
Posterior spinal artery

The posterior spinal artery arises from the vertebral artery, adjacent to the medulla oblongata....
, the membrana tectoria and alar ligaments.

umans, the foramen magnum is farther underneath the head than in great apes.






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In anatomy
Anatomy

Anatomy is a branch of biology that is the consideration of the body plan. It is a general term that includes human anatomy, animal anatomy and plant anatomy ....
, in the occipital bone
Occipital bone

The occipital bone, a saucer-shaped membrane bone situated at the back and lower part of the skull, is trapezoid in shape and curved on itself. It is pierced by a large oval aperture, the foramen magnum, through which the cranial cavity communicates with the vertebral canal....
, the foramen magnum (Latin: 'great hole') is one of the several oval or circular apertures in the base of the skull
Skull

The skull is a bone structure found in the head of many animals. The skull supports the structures of the face and protects the head against injury....
 (the foramina
Foramina of skull

The following is a list of holes, or foramen, in the base of the skull and what goes through each of them. Arranged from anterior to posterior:...
), through which the medulla oblongata
Medulla oblongata

The medulla oblongata is the lower portion of the brainstem. It deals with Autonomic nervous system functions, such as breathing and blood pressure....
 (an extension of the spinal cord
Spinal cord

The spinal cord is a long, thin, tubular bundle of neuron and glia that extends from the brain. The brain and spinal cord together make up the central nervous system....
) 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
Vertebral artery

The vertebral arteries are branches of the subclavian artery.The two vertebral arteries and the basilar artery are sometimes together called the vertebrobasilar system, which supplies blood to the posterior part of circle of Willis and anastomoses with blood supplied to the anterior part of the circle of Willis from the carotid arteri...
, the anterior
Anterior spinal artery

In human anatomy, the anterior spinal artery is the blood vessel that supplies the anterior portion of the spinal cord. It arises from branches of the vertebral artery and is supplied by the anterior segmental medullary artery, including the artery of Adamkiewicz, and courses along the anterior aspect of the spinal cord....
 and posterior spinal arteries
Posterior spinal artery

The posterior spinal artery arises from the vertebral artery, adjacent to the medulla oblongata....
, the membrana tectoria and alar ligaments.

Importance

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.

The foramen magnum is the border line above which is the brain, and below, the spinal cord.

Additional images


See also

  • Posterior cranial fossa
    Posterior cranial fossa

    The posterior cranial fossa is part of the intracranial cavity, located between the foramen magnum and tentorium cerebelli. It contains the brainstem and cerebellum....


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