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Citation, DOI & article dataCitation: Morgan, M., Murphy, A. Skull (Towne view). Reference article, Radiopaedia.org. (accessed on 26 Sep 2022) https://doi.org/10.53347/rID-37239 The Towne view is an angled anteroposteriorradiograph of the skull and visualizes the petrous part of the pyramids, the dorsum sellae and the posterior clinoid processes, which are visible in the shadow of the foramen magnum. On this page:This projection is used to evaluate for medial and lateral displacements of skull fractures, in addition to neoplastic changes and Paget disease.
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ReferencesRelated articles: Imaging in practicePromoted articles (advertising)Just for you: FREE 60-day trial to the world’s largest digital library.The SlideShare family just got bigger. Enjoy access to millions of ebooks, audiobooks, magazines, and more from Scribd. Read free for 60 days Cancel anytime. The skull consists of 22 bones: 14 facial bones Caldwell's Method
etc. Registered Radiologic Technologist, Medical Student The skull consists of 22 bones: 14 facial bones Caldwell's Method etc. Sella Turcica Location in the SkullThe sella turcica (also called the hypophyseal fossa or pituitary fossa) is a midline saddle-shaped depression in the sphenoid bone that is lined by the dura mater. Although it is a relatively small area, it is an extremely valuable piece of real estate in the brain because it forms the bony seat for the pituitary gland which it houses and partially encloses. One of the main reasons for imaging the sella turcica is that it is a window to the pituitary, a pea-sized gland that is often called the master endocrine gland because of the major role it plays in regulating vital body functions. Sellar components are easily demonstrated by several radiographic planes and angles. Radiology techs need to be aware of the anatomy of this region as well as correct radiographic angles and patient positioning techniques to demonstrate the sella turcica and surrounding structures accurately. Many disease processes originating inside and outside the cranium cause radiographic changes in the pituitary fossa or sella turcica. These radiographic changes are valuable diagnostic aids for a number of endocrine disorders. For example, enlargement of the sella turcica or distortions in its shape and contour may be related to pituitary pathology. The sella turcica is located deep within the cranium but can be demonstrated on a number of projections used in skull radiography. This picture of the skull (with temporal and parietal bones removed) shows the location of the sella in red. Anatomy of the Sella Turcica The anterior, posterior, and inferior walls of the sella turcica are bony while the lateral walls and roof are made of dura that slings between the anterior and posterior clinoid processes. The dural roof of the pituitary fossa has fenestrations for the infundibulum. The terms sella turcica and pituitary fossa are often used synonymously, but in fact the pituitary fossa has 4 parts:
In addition to the pituitary gland, the pituitary fossa contains the pituitary vessels, the anterior and posterior intercavernous sinuses, and cerebrospinal fluid. Surrounding anatomical structures include the sphenoid sinus, clivus, brainstem, basilar artery, infundibulum, optic chiasm, hypothalamus, and cavernous sinus. In normal individuals, the sella turcica is less than 15 mm long and less than 12 mm deep. Radiographic Signs Associated with Pathology of the Pituitary Gland Changes in and around the sella turcica can reflect numerous intracranial pathologies, not limited to the pituitary gland. Here are some of the common radiographic findings in the sella turcica and associated pathologic conditions:
Pathological Conditions of the Sella TurcicaEmpty Sella
Syndrome Pituitary Adenomas Non-Pituitary Tumors of the Sellar Region Craniopharyngiomas Pituitary Apoplexy Intrasellar Aneurysms Rathke Cleft Cyst Radiography of the Sella TurcicaIn the past several decades, investigation of the pituitary and sellar region with radiographic imaging has undergone significant advancement. Computed tomography (CT) and magnetic resonance imaging (MRI) have largely replaced plain radiography, cerebral pneumography, and angiography due to a superior ability to delineate soft tissues. MRI is the modality of choice for the evaluation of sellar and parasellar lesions. Nonetheless, X-ray remains a useful tool that can yield valuable diagnostic information about pathology in this region. Plain radiography may be used for screening purposes or to identify calcifications and/or destructive changes of the sella turcica and adjacent bony structures. The sella turcica is best demonstrated on lateral radiographs of the skull. The floor can be visualized on angled frontal radiographs, such as the Caldwell view. Radiographic Projections of the Sella TurcicaSkull Lateral Supine: A right or left non-angled lateral view of the skull demonstrates details of the cranium on the side closest to the IR. The sella turcica and dorsum sellae are visualized in profile on this projection. In a properly positioned lateral skull X-ray, the line extending from the outer canthus of the eye to the external auditory meatus is perpendicular to the table and the anterior and posterior skull is visualized. Skull PA Axial (Caldwell View): This is a caudally angled occipito-frontal projection that demonstrates the floor of sella turcica. In a properly positioned Caldwell projection, the IR is perpendicular to the orbitomeatal line (OML) and the X-rays pass at an angle of 15 degrees from behind the head and exit at the nasion. Video Credit : Jeremy Enfinger Skull PA Axial (Haas View): This is an occipito-frontal projection that is angled 25 degrees cephalad to the orbitomeatal line (OML). The patient sits or stands facing an upright Bucky with the forehead and nose touching the IR. The neck is flexed to bring the OML perpendicular to the IR. This projection can also be done with the patient prone. The midsagittal plane is aligned perpendicular to the Bucky and the rays are angled at 25 degrees cephalad to the OML. The patient’s head should not be rotated or tilted. This view demonstrates the dorsum sellae in the shadow of the foramen magnum. Video Credit : Chase Smith Visit here to know more about x-ray positioning . What is the central ray angulation for the AP axial projection of the TMJ?Positioning TMG SINUS MANDIBLE. What is the central ray angle and direction for the AP axial reverse Caldwell of the cranium?The Reverse Caldwell. AP Axial skull. The CR is angled 15 degrees cephalic to the OML and centered at the Nasion.
Which of the following are demonstrated on an AP axial projection of the skull?Skull - Facial - Sinuses. Where does the central ray enter for a SMV projection?Final Exam Review from Class. |