Note the sclerotic fused sphenooccipital synchondrosis/fissure ( thin black arrow ). The basisphenoid (BS) portion of the clivus superiorly and anteriorly is located within the middle cranial fossa, whereas the basi occiput (BO) portion of the clivus is a portion of the occipital bone, within the posterior cranial fossa. The carotid canal (“c”) enters the petrous portion of the temporal bone, extending cranially with vertical and horizontal segments. ( C ) Axial CT through the middle cranial fossa floor showing the “high-heel shoe” appearance of foramen ovale (the “toe of the shoeprint”), and foramen spinosum (the “heel”) within the sphenoid bone. ![]() Note the planum sphenoidale, foramen rotundum (FR) transmitting V2 along the lateral sphenoid sinus, and vidian canal transmitting the vidian nerve inferomedially. ( A, B ) Coronal and axial CT image demonstrating the relationship of the optic nerve and superior orbital fissure to the clinoid process, with the optic nerve medial to the clinoid process, and the superior orbital fissure inferior and lateral to the clinoid process. In addition to housing the pituitary gland, the central skull base contains numerous foramina and canals through which many important structures pass, including cranial nerves (CNs) II to VI and the internal carotid artery ( Fig. 3, Table 1 ).Ĭentral skull base. The posterior border between the central and posterior skull base is formed by the superior margin of the petrous ridge of the temporal bone, the basi sphenoid portion of the clivus, and the dorsum sella (see Fig. 1 ). The floor is formed by the greater wing and central body of the sphenoid bone, the sphenoid sinus, and the sella. The anterior border of the central skull base is formed by the posterior margin of the lesser wing of the sphenoid bone, clinoid process and tuberculum sella. The central skull base, formed by the sphenoid and anterior temporal bones, separates the pituitary gland (within the sella), the cavernous sinuses (including the carotid artery and cranial nerves), the Meckel cave, and the temporal lobes superiorly from the sphenoid sinus anteriorly and inferiorly, and the extracranial soft tissues deep to the skull base inferiorly, including the masticator, parotid, parapharyngeal, and pharyngeal mucosal spaces. ( B ) Axial CT showing bilateral anterior and posterior ethmoid artery canals (AEA and PEA respectively), corticated and in a characteristic location that should not be mistaken for fracture. Note the horizontal trajectory of the anterior ethmoid artery canal, with its corticated margins and medial tapering. The lateral lamella extends cranially to form the ethmoid roof. ![]() ( A ) Coronal CT demonstrating the olfactory groove, bordered by the crista galli, cribriform plate, and lateral lamella. ![]() The associated risk and extent of complications often depends on the location and pattern of the fracture, which is in turn determined by the mechanism of injury and type of impact.Īnterior skull base. Although facial fractures often require repair to improve function and cosmesis, the management of patients with skull base injury is dependent on the extent of associated intracranial injury and other complications. Skull base injury is often seen in the setting of complex facial or orbital fractures, and detection of basilar skull fractures is important, as even linear nondisplaced fractures can be associated with numerous critical complications, including intracranial and orbital injuries, cerebrospinal fluid (CSF) leak, cranial nerve palsies, and vascular injuries. Penetrating trauma, particularly gunshot wounds, are seen much less frequently, accounting for less than 10% of cases. Skull base fractures, those fractures that extend through the floor of the anterior, middle, or posterior cranial fossa, occur in an estimated 7% to 16% of nonpenetrating head injuries, and are due to a relatively high-velocity trauma, most often high-speed motor vehicle accidents, although motorcycle collisions, pedestrian injuries, falls, and assault are additional associated causes. According to the 2013 National Trauma Data Bank maintained by the American College of Surgeons, of 833,311 adult trauma admissions reported from 805 facilities across the United States, approximately 36% sustained an injury to the head. Head trauma is one of the most common reasons for visits to the emergency department in the United States.
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