Skull base and vault

By Dr.Safa Ahmed Rheumatologist (MSc.) base

• This represents the floor of the on which the lies. of the base of the skull

• 5 bones compose the : 1. Frontal 2. Temporal bones 3. 4. 5. Cranial

• It is formed by the floor of the cranial cavity. • It is divided into 3 distinct parts: 1. Anterior 2. 3.

Anterior cranial fossa

• Formed by the following bones: 1. Orbital plate of 2. of ethmoid bone 3. Small wings and part of the . Contents: frontal lobes of the brain. Middle cranial fossa

• It is deeper than the anterior fossa. • Formed by parts of the sphenoid and temporal bones. • Contents: temporal lobes and on which the lies. Posterior cranial fossa

• It is the most inferior of the fossae • Mainly formed by the occipital bone. • Contents: , medulla, pons. internal acoustic Foramina in the base of skull

• Foramen ceacum • Optic foramen: transmit the and into . • Foramen magnum: is an oval shaped foramen in the base of the skull that transmits the as it exits the cranial cavity. • : lies in the sphenoid greater wing and transmits several nerves. • : transmit the (9th, 10th,11th) and . • : provide a passage for the 7th and 8th cranial nerves and artery to the . • Other foramina: , , and foramen lacerum. • These foramina transmit the cranial nerves( 12 cranial nerves).

Vault of the skull

• Bones of the vault: 1. Frontal bone 2. Parietal bones 3. Occipital bone 4. Temporal bones 5. Greater wings of sphenoid bone • It provides protection to the brain. • At birth these bones are not tightly bound to each other to allow passage of the head of the newborn through the birth . • Openings in the vault called the fontanells: anterior and posterior. The anterior remains open up to 2 years after birth while the ossifies within 6-8 months after birth. • Fractures in the vault affect mainly the parietal and frontal bones.