While most nerves come from the spinal cord, 12 pairs of cranial nerves (CN I-XII) emerge directly from the brain and leave the cranial cavity through several foramina to innervate (mainly) the head and neck. All the nerves are associated with nuclei in the brainstem, except the olfactory nerve (CN I) which projects from the periphery into the olfactory bulb and the optic nerve (CN … Continue reading Cranial nerves
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 cranium (specifically the neurocranium) is the superoposterior part of the skull that houses and protects the brain. It can be split into the calvarium (skull cap) and cranial base with the remainder of the skull being the facial skeleton. It consists of 8 of the 22 skull bones: the frontal, ethmoid, sphenoid, temporal (x2), parietal (x2) and occipital bones. Many structures pass into and out of the cranial cavity … Continue reading Cranium
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