The Sectional Imaging Anatomy And Three-dimensional Visualization Of The Hypoglossal Nerve

The hypoglossal nerve is a motor cranial nerve,which mainly controls the movement of the tongue and participates in activities such as breathing,swallowing and speaking.Therefore,the injury of hypoglossal nerve will affect the movement and coordination of tongue.It has been found that any diseases affecting the function of hypoglossal nerve,some which can result in unilateral or bilateral hemiplegia of lingual muscle.The diameter of hypoglossal nerve is relatively small,the overall shape is winding,and the adjacent structures are difficult to distinguish,the imaging diagnosis of hypoglossal nerve diseases needs clear sectional specimens and high-resolution images.In order to make clear imaging and effective differential diagnosis of hypoglossal nerve injury,we must fully understand the normal anatomical structure of hypoglossal nerve and its main branches.Our study identified these landmark structures and observed the relationship between the hypoglossal nerve and peripheral blood vessels.By comparing the sectional specimens,magnetic resonance images and three-dimensional reconstruction images of the hypoglossal nerve,the hypoglossal nerve was carefully segmented and the landmark structure was defined.These results can be used to identify the hypoglossal nerve during the operation and provide certain anatomical and imaging basis for reducing the iatrogenic complications during the operation.In the first part,we mainly compared the cryosectional specimen with the corresponding magnetic resonance images to clarify the landmark structure of the hypoglossal nerve.The results showed that the hypoglossal nerve was divided into four segments:cerebellomedullary cistern segment,hypoglossal nerve canal segment,cervical segment and intralingual segment.The cervical segment is divided into the posterior mandibular fossa segment,the carotid triangle segment and the digastric triangle segment.The landmarks of cistern segment are occipital bone,vertebral artery and internal orifice of hypoglossal nerve canal.The landmark structures of the canal segment are the hypoglossal nerve canal,the odontoid process of the axis and the jugular foramen.The landmarks of the cervical segment are internal jugular artery and vein,vagus nerve,mandibular hyoid muscle,hyoid muscle.The landmarks of the intralingual segment are the lingual nerve and lingual artery.In the second part of this research,we made a statistic on the displayed hypoglossal nerve and adjacent arteries.This study found that the 3D-SPACE sequence has obvious advantages in the display and imaging diagnosis of the hypoglossal nerve.This sequence can clearly display the hypoglossal nerve and its surrounding structures,providing certain imaging basis for the operation safety around the hypoglossal nerve.In this study,software was used to segment the hypoglossal nerve and its surrounding structures on a continuous thin layer specimen to obtain a complete three-dimensional reconstruction of the hypoglossal nerve.Three-dimensional visualization can reconstruct the detailed anatomical features and complex peripheral structures of the hypoglossal nerve,which plays an important role in the diagnosis and treatment of hypoglossal nerve related diseases.In conclusion,the lesions of the hypoglossal nerve often need to be observed at different levels by a variety of methods.The 3.0T MRI scanned by SPACE sequence can clearly show the hypoglossal nerve.Three-dimensional reconstruction of the hypoglossal nerve is helpful to describe the hypoglossal nerve surrounded by the vascular structure,fully understand the overall course and key structure of the hypoglossal nerve,and provide anatomical and imaging basis for identifying and protecting the hypoglossal nerve during the operation.