The skull base contains several foramina through which passes structures (e.g. the cranial nerves) into or out of the skull vault. Foramen Primary structures passing through Cribiform plate fibres of CN I Optic canal CN II, ophthalmic artery Superior orbital fissure CN III, IV, Va, VI, superior & inferior ophthalmic veins Foramen rotundum CN Vb Foramen ovale Otic ganglion (inferiorly)Vc (cranial nerve)Accessory meningeal arteryLesser petrosal … Continue reading Skull base foramina

The occipital bone lies centrally in the posterior cranial fossa and is divided into squamous (flat) and basal parts. It contains the hypoglossal canals (for CN XII) and foramen magnum (for brain stem and vertebral arteries). Other landmarks include the occipital condyles (which articulate with the first vertebra atlas), occipital protuberance and nuchal lines (the superior of which attaches to the trapezius muscle). Continue reading Occipital bone

Fontanelles The bones of the skull cap ossify in membrane and are mobile at birth, meaning there are soft membranous gaps that are the 6 fontanelles. The fontanelles allow the cranial vault to expand as the brain enlarges during child development and the skull to flex when squeezing through the birth canal during childbirth. These fontanelles include: the diamond-shaped anterior fontanelle (between frontal and parietal bones), … Continue reading Fontanelles & sutures

The space within the cranium is the cranial cavity whose floor is divided into the anterior, middle and posterior cranial fossa, a high to low three-tiered structure. The cranial fossa is made up of several bones that contribute to the skull base and contain several foramina through which structures enter and exit. This is summarised as follows: Cranial fossa Contributing bones Foramina Contents Anterior (highest) frontal, … Continue reading Cranial fossae