Which region of the skull base contains the foramen magnum?

Which region of the skull base contains the foramen magnum?

occipital. occipital,, bone forming the back and back part of the base of the cranium, the part of the skull that encloses the brain. It has a large oval opening, the foramen magnum, through which the medulla oblongata passes, linking the spinal cord and brain.

What is the foramen magnum where is it located Why is it significant?

The foramen magnum (Latin: great hole) is a large, oval-shaped opening in the occipital bone of the skull. It is one of the several oval or circular openings (foramina) in the base of the skull. It also transmits the accessory nerve into the skull. The foramen magnum is a very important feature in bipedal mammals.

Where is the foramen located in the body?

A foramen (plural: foramina ) is an opening inside the body that allows key structures to connect one part of the body to another. The skull bones that contain foramina include the frontal, ethmoid, sphenoid, maxilla, palatine, temporal, and occipital.

What is foramen magnum bordered by?

occipital bone
The foramen magnum is an oval-shaped opening in the occipital bone bound by the basiocciput anteriorly, the occipital condyles laterally, and the supraocciput posteriorly.

How does the location of the foramen magnum indicate if a species was bipedal?

If the foramen magnum indicates the position of the spine in relation to the head, and therefore whether the creature was bipedal or moved about some other way, then the position of the opening might indicate when our ancestors developed the upright, bipedal posture so often taken to be the hallmark of humanity.

In what way do you think the location of the foramen magnum relates to the movement of each species?

The foreamen magnum relates tot the movement of each species as well because the spinal cord is connected to the brain and that’s what sends signals to the body in order to move.

Why is the foramen magnum located where it is in apes?

In pronograde (with a body more parallel to the ground), quadrupeal apes have a cranium that projects anterior of the vertebral column, and thus the foramen magnum is positioned and oriented posteriorly. Other cranial base measurements have not been able to differentiate hominins from non-hominin apes.

What is the meaning of a foramen magnum?

Definition of foramen magnum : the opening in the skull through which the spinal cord passes to become the medulla oblongata.

What articulates at the foramen magnum?

The paired lateral or condylar parts are situated at the sides of the foramen magnum. The occipital condyles, which articulate with the atlas, protrude from the external surface of this part. These condyles are located lateral to the anterior half of the foramen magnum.

What would the position of the foramen magnum tell us about how an animal moves?

Why is the location of the foramen magnum important in differentiating ancient hominid species?

The foramen magnum position has been cited as evidence of bipedal locomotion (a hominin characteristics), so fossil hominins are classified based on evidence of an anteriorly placed foramen magnum, as is the case for Ardipithecus and Sahelanthropus.

Why is the location of the foramen magnum different between the human and the chimp?

In humans, the foramen magnum is positioned centrally, facing directly downwards, which allows the human body to be oriented vertically for bipedalism. In chimpanzees and other apes, the foramen magnum is positioned towards the back of the skull with the spinal cord exiting at a slight angle.

Where is the foramen magnum located?

The foramen magnum is situated in the occipital bone, and forms around the base of the brainstem (the medulla oblongata), separating the brain above from the spinal cord below.

How is the foramen magnum different in apes?

In apes the foramen magnum lies well behind (posterior) of the bitympanic line, posterior of a relatively long basioccipital. In addition to being more posteriorly positioned, the foramen magnum in apes is more vertically oriented (opening backwards and downwards, rather than directly downwards).

How does the alar ligament divide the foramen magnum?

The alar ligament, which is attached on each side to the tubercle of occipital condyle, divides the foramen magnum into an anterior smaller compartment and a posterior larger compartment. The foramen magnum varies in size between individuals. Earlier ossification of the occipital bone leads to a smaller foramen.

What are the gray ridges in the foramen magnum?

Looking at the outer surface of the foramen magnum (below), we immediately notice the gray ridges that form the left and right occipital condyles. These are rounded structures that form an articulation point with the first vertebra (C1), also called the atlas. The joint is, therefore, called the atlanto-occipital joint.