The anterior view of the skull also displays the three clinically important openings through which sensory nerves pass to supply the face: the supraorbital foramen, infraorbital foramen, and mental foramen (see pp.77 and 93).Ĭ Paranasal sinuses: pneumatization lightens the boneĪnterior view. The paranasal sinuses are shown schematically in C. The nasal cavity, like the orbits, contains a sensory organ (the olfactory mucosa). The bony margins of the anterior nasal aperture mark the start of the respiratory tract in the skull. The boundaries of the facial skeleton (viscerocranium) can be clearly appreciated in this view (the individual bones are shown in B). This explains why congenital defects of intramembranous ossification affect both the skull and clavicle (cleidocranial dysostosis).Į Bones of the neurocranium and viscerocraniumį Bones of the desmocranium and chondrocranium The clavicle is the only tubular bone that undergoes membranous ossification. Elements derived from intramembranous and endochondral ossification (desmocranium, chondrocranium) may fuse together to form a single bone (e.g., the occipital bone, temporal bone, and sphenoid bone). The bones of the skull either develop directly from mesenchymal connective tissue (intramembranous ossification, gray) or form indirectly by the ossification of a cartilaginous model (enchon- dral ossification, blue). The greater size of the neurocranium (cranial vault) relative to the viscerocranium (facial skeleton) is a typical primate feature directly correlated with the larger primate brain. The skull forms a bony capsule that encloses the brain, sensory organs, and viscera of the head. The bones are shown in different colors to demonstrate more clearly their extents and boundaries.Ĭ Bones of the neurocranium (gray) and viscerocranium (orange) The teeth are described in a separate unit (see p. The chapter as a whole is intended to familiarize the reader with the names of the cranial bones before proceeding to finer anatomical details and the relationships of the bones to one another. This unit reviews the principal structures of the lateral aspect of the skull. The individual bones and their salient features as well as the cranial sutures and apertures are described in the units that follow. This view was selected as an introduction to the skull because it displays the greatest number of cranial bones (indicated by different colors in B).
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