This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
The dura mater in children is more firmly attached to the interior of the skull than in adults. If, therefore, a true fracture does occur, laceration of the dura is more liable to be produced. This firm attachment also prevents the formation of epidural hemorrhages, because the force of the blow is not sufficient to loosen the dura from the bone, and when the middle meningeal artery is torn, as Marchant has pointed out, the bleeding is more apt to be external than internal.
The infant has the bones of the face so slightly developed that there is no room for the cavities which afterward develop in them. The ridges of the bones also become more marked as age advances. The young child has no superciliary ridges.
The maxillary sinus, or antrum of Highmore, and the mastoid antrum are the only cavities that exist at birth. They are both much smaller than they ultimately become. The mastoid antrum in relation to the size and age of the child is comparatively large, being about five millimetres in diameter. As the bone in the child is undeveloped, and the tympanum lies nearer to the surface, the antrum likewise is somewhat higher and nearer to the surface than is the case in adults. This should be borne in mind when operating on the bone in this region (Fig. 13).
The frontal, ethmoidal, and sphenoidal sinuses appear about the seventh year, but it is not until puberty is reached that they really begin to develop. The mastoid cells likewise appear at puberty and increase with age. At birth, they are represented by simple cancellous bone.
Fig. 12. - Infant's skull, showing anterolateral and posterolateral fontanelles.
Fig. 13. - The surface of the temporal bone has been chiselled off, showing the relative size and position of the mastoid antrum and external auditory meatus.