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Face vs skeleton4/12/2023 Often, their particular location and other associated imaging features can be diagnostic. Moreover, radiologists should also be familiar with embryonic abnormalities affecting the skull base. Awareness of anatomic variants is crucial in surgical planning and to avoid potential confusion with skull base lesions. Diagnostic imaging may require the use of different techniques, most often CT, MRI, bone scintigraphy, and PET-CT and is crucial in patient’s management, as the skull base is hidden from clinical inspection. This chapter specifically focuses on the imaging techniques, developmental anomalies, skull base lesions originating from embryonic remnants, skull base infection, and other diffuse skull base lesions. Owing to this unique location, it can be affected both by intrinsic lesions originating from the bony elements of the skull base and by lesions originating outside the skull base proper or from trapped embryonic remnants. The skull base is made of flat bones that separate the intracranial compartment from the extracranial head and neck. These sinuses are linked to the nasal cavity and, in life, irritation of their mucous membranes may cause swelling, draining, and headache-related discomfort.Īlexandra Borges MD, in Skull Base Imaging, 2018 Abstract There are four basic sets of sinuses, one each in the maxillae, frontal, ethmoid, and sphenoid. Sinuses are void chambers in the cranial bones that enlarge with the growth of the face. Occipitomastoid sutures pass between the occipital and temporals on either side of the vault. Parietomastoid sutures pass between the parietals and the temporals, constituting posterior extensions of the squamosal suture. The sphenooccipital, or basilar suture (actually a synchondrosis) lies between the sphenoid and the occipital. Squamosal sutures are unusual, scale-like, beveled sutures between temporal and parietal bones. The lambdoidal suture passes between the two parietals and the occipital. The coronal suture lies between the frontal and parietals. The metopic suture passes between unfused frontal halves and only rarely persists into adulthood. The sagittal suture passes down the midline between the parietal bones. For example, zygomaticomaxillary sutures are sutures between the zygomatics and maxillae, and frontonasal sutures are short sutures between the frontal and nasals. Many of these sutures derive their name directly from the two bones that contact across them. Cranial articulations in the adult human skull are summarized in Figure 7.8. In the adult the skull bones contact along joints with interlocking, sawtooth, or zipper-like articulations called sutures. These “soft spots,” or fontanelles, are cartilaginous membranes that eventually harden and turn to bone. One-third natural size.Īt birth the skull contains intervals of dense connective tissue between plates of bone. All specimens are shown in facial and lateral views. (Left, below, and opposite) Note the change in proportions of face and vault through the series. A large, triangular inca bone is occasionally found at the rear of human crania.įigure 7.7. In addition to the 28 normal skull bones, there are often sutural bones (also called Wormian bones, or extrasutural bones), which are irregular ossicles that occur along some sutures. For this reason, it is advisable to begin study with young adult specimens, in which the bones are most readily recognizable. Distinguishing these bones is occasionally made difficult because some of them fuse together during adult life. When the ear ossicles (three pairs of tiny bones associated with hearing) are included and the hyoid excluded, there are usually 28 bones in the adult human skull. These anterior, middle, and posterior cranial fossae are respectively occupied by the frontal lobes, temporal lobes, and cerebellum of the brain. The three basic divisions of the endocranial surface at the base of the neurocranium correspond to the topography of the base of the brain. The splanchnocranium is the facial skeleton. The calotte is the calvaria without the base. The calvaria (or calvarium) is the cranium without the face. The cranium is the skull without the mandible. The skull is the entire bony framework of the head, including the lower jaw. It is worthwhile to review the proper use of terminology. Terms such as this have very specific meanings to anatomists and osteologists. The term “ skull” is often misused in common speech.
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