Cranial cavity

1. Cranial cavity • Internal surface of vault of skull,show sagital groove in median plane. • Floor of cranial cavity is formed by upper surface of base of skull, it’s divided into 3 fossa: 1- ant. Carnial fossa 2- middle cranial fossa 3- post. Cranial fossa

2. Anterior Cranial fossa: It’s floor formed by 3 bones : 1) Ethmoid bone 2) orbital plate of frontal bone which form roof of orbit 3) sphenoid bone • It’s present crista galli which median projection of ethmoid bone • On each side of crista galli there is cribiform plate of ethmoid • foramen cecum • Frontal crest

3. middle cranial fossa • It consists of middle narrow part & 2 expanded lateral part • Median part is formed by body of sphenoid which called sella turcica & includes the following: • Dorsum sallae • Hypophyseal fossa. • Tuberculum sallae • Medial end of lesser wing sphenoid projects ant. Glenoid process. • Post. Glenoid process at lateral end • sup. Orbital fissure lies between greater&lesser wing of sphenoid.

4. post. Cranial fossa • Jugualr foramen: Foramen magnum which contain lower end of medulla oblingnata, • it’s the biggest foramen • Which transmit vertebral A. • Hypoglossal canal • It’s found between jugular tubercle which which elevation between jugular foramen & foramen magnum • Transmit hypoglossal N. • Below foramen magnum there is internal occipital crest to reach internal occipital protuberance.

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