What is the occipital bone and where is it located?

The occipital bone is a curved bone that forms the posterior part and base of the skull. It features the foramen magnum, an opening through which the spinal cord passes, and contributes to both the cranial vault and cranial base.

What are the main parts of the occipital bone?

The occipital bone consists of four parts arranged around the foramen magnum: the squamous part (posterior and superior), two condylar parts (lateral), and the basilar part (anterior).

What structures are found on the squamous part of the occipital bone?

The squamous part has an external surface with features like the external occipital protuberance and nuchal lines, and an internal surface with grooves for sinuses and the internal occipital protuberance.

What is the function of the occipital condyles?

The occipital condyles are located on the condylar parts and articulate with the atlas vertebra, allowing for nodding movements of the head.

What is the hypoglossal canal and what does it transmit?

The hypoglossal canal is a passage located lateral to the anterior condyle on the condylar part. It transmits the hypoglossal nerve (CN XII), which controls tongue movement.

What is the clivus and what is its role?

The clivus is a shallow groove formed by the basilar part of the occipital bone when articulated with the sphenoid bone. It supports the brainstem on the superior surface of the skull base.

How does the occipital bone develop and what are some clinical implications?

The squamous part ossifies partly in cartilage and partly in membrane, which can lead to variations like an interparietal bone if fusion fails. The basiocciput fuses with the sphenoid by age 25, aiding in age estimation in medicolegal contexts.

Occipital Bone – Foramen Magnum & Condyles

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