ENDOSCOPIC ANATOMY OF CLIVUS,CCJ&PF скачать в хорошем качестве

ENDOSCOPIC ANATOMY OF CLIVUS,CCJ&PF

Anatomy of the Clivus and Craniovertebral Junction (CCJ) The clivus is a crucial bony region in the skull base formed by the posterior portion of the sphenoid body, called the basisphenoid, and the basilar part of the occipital bone, known as the basiocciput. This structure serves as an essential anatomical landmark due to its proximity to vital neural and vascular components. • Posteriorly, it is related to the posterior cranial fossa. • Anteriorly, it connects to the sphenoid sinus and nasopharynx. • Superiorly, it is bordered by the sella turcica. • Inferiorly, it extends to the foramen magnum, where the spinal cord begins. The clivus is subdivided into three parts: 1. Upper third: Located at the sphenoid sinus and includes the dorsum sellae, making it a key area in neurosurgical procedures targeting pituitary tumors or lesions of the midline skull base. 2. Middle third: This corresponds to the basiocciput and is aligned with the caudal ends of the petrous temporal bones, forming an important transition zone between the clival and cranial base regions. 3. Lower third: This is formed by the basiocciput and connects to the nasopharynx. The intracranial surface in this area lies near the medulla oblongata, a critical structure of the brainstem. The internal carotid arteries (ICAs) run laterally along the clivus and are critical considerations during surgical approaches to avoid vascular injury. Additionally, lateral dissections in this area are limited by significant structures, including the jugular foramen, occipital condyles, and hypoglossal canal. Understanding the Craniovertebral Junction (CCJ) The CCJ is a highly intricate region located between the skull base and the upper cervical spine, specifically behind the nasopharynx. This area can be accessed surgically through an endoscopic transnasal approach, which allows direct visualization of deep-seated structures. Key anatomical components include: • The vertebral arteries, which ascend through the foramen magnum and form part of the basilar artery. • The posterior and superior cerebellar arteries, which supply vital areas of the brainstem and cerebellum. • Cranial nerves III through VIII, which are involved in motor and sensory functions. The endoscopic transnasal approach typically involves lateral displacement of the nasopharyngeal mucosa and the longus capitis muscle to expose the anterior arch of C1 and the odontoid process of C2. This technique enables precise access to challenging tumors or other lesions in the CCJ while preserving surrounding structures. Tumor Types Affecting the Clivus and CCJ Several lesions may develop in this region, including both benign and malignant tumors. 1. Chordomas: These rare, slow-growing tumors originate from remnants of the notochord and account for approximately 0.1% of all brain tumors. They typically present as midline lesions in the skull base, infiltrating bone and causing significant surgical challenges due to their recurrence potential. 2. Chondrosarcomas: These arise from primitive mesenchymal cells or embryonal rests in the cartilage matrix of the cranium. Though also rare, chondrosarcomas are aggressive tumors with a predilection for the skull base and are often located paramedially. Other lesions, such as inflammatory or infectious diseases, may also occur but are less common. Each of these conditions underscores the importance of detailed anatomical knowledge and advanced surgical planning. Conclusion A comprehensive understanding of the clivus and CCJ anatomy, as well as their relationships with adjacent structures, is essential for successful surgical outcomes. Modern endoscopic techniques provide enhanced visualization and precision, offering safer approaches to treat lesions in these complex regions. #nose #throathealth #ear #science #ent #otolaryngology #nosebleed #tonsils #anatomy #biology