Study of Jugular Foramen - A Case Report

The jugular foramen at the base of the skull varies in shape and size the foramen lies at the petrous part of temporal bone and behind by the occipital bone. It's irregular in shape. Usually the right foramen is larger than the left. The variation in the foramen is observed in different racial group and sexes. The shape and size of foramen is inversely related to size of sigmoid sinus. Petrosal portion contains the inferior petrosal sinus. Sigmoid portion receives the sigmoid sinus. Intrajugular portion contains cranial nerves IX, X and XI. AIM: To analyze the length and width of jugular foramen. To determine the side dominance of the foramen. MATERIALS AND METHODS: A total of 32 jugular foramen in dry adult skulls from Department of Anatomy, CHRI were used for the present study. Sagittal and transverse diameters were measured using digital vernier caliper. OBSERVATIONS: The overall dimensions of Jugular foramen were recorded on both sides. The mean transverse diameter (width) on the right and the left side were 11.779mm and 10.901mm respectively. The mean sagittal diameter (length) on the right and left side were 10.141mm and 09.025mm. In 62.5% of cases the right foramen was larger , in 37.5% of cases left foramen was larger than the right. Dome was found bilaterally in 50% of cases, The unilateral presence of dome was equally distributed to both sides. Jugular process was found bilaterally in 18.75%, right side 31.25% and left side in 18.75% of cases. The process was absent in 31.25% cases. Complete Septation of the foramen was found in 12.5% on right side, 6.25% on left side. Partial Septation was seen in 87.5% on right side, in 93.74% on left side. CONCLUSION: In comparison with the previous studies, the width of the Jugular foramen is slightly higher where as the length is slightly lower. There is an increase in the occurrence of bony partition compared to the previous study. Dimension, dome and Septation were significantly higher on right side than on left. Jugular foramen serves as an important land mark during surgeries of posterior cranial fossa. I. Introduction In anatomical, a foramen is considered as opening. Foraminae transmits nerves, arteries, veins, or other structures to connect one part of the body with another part. The human skull has numerous foramina through which cranial nerves, & vessels and other structure pass. The skull bones contain foraminae that include the frontal, ethmoid, sphenoid, maxilla, palatine, temporal and occipital. There are 21 foramina present in all of the major bones of the skull. Jugular foramen is a passage or fissure between the petrous part of the temporal bone and the jugular process of the occipital bone, sometimes divided into two by the intrajugular processes. Jugular fossa contains the junction of the largest sigmoid sinus and internal jugular vein. Inferior petrosal sinus, glossopharyngeal nerve, vagus nerve, accessory nerve, meningeal branches of the ascending pharyngeal and occipital arteries are the structures passing through this foramen. The jugular foramen is a complex bony canal, which transmits vessels and nerves from the posterior cranial fossa through the base of the skull into the carotid space. According to Quain's Elements of Anatomy, the jugular foramen is described as being divided into three compartments. The anterior part is sometimes completely separated by a bony spicule (Intrajugular process).According to Cunningham's, the edge of the occipital bone forms a jugular notch and the petrous part of temporal bone is excavated to from a jugular fossa, which accommodates the superior bulb of jugular vein. According to Gray's anatomy lower border of jugular foramen are smooth and upper border sharp and notched. The margins of notch extend and divided in to three compartments. The larger size of right jugular foramen accounts to the superior sagittal sinus draining into the right transverse sinus. But there is a very wide variation in the anatomy of the intracranial venous sinuses which accounts for variation in size and shape of jugular foramina. Complete division of the foramen by a bony septum is comparatively rare. In some cases the foramen was found to be divided into three compartments. Incomplete bony Septation, which in life is probably completed by cartilage. In syndrome of the jugular foramen (Vernet's syndrome), there is paralysis of the 9th, 10 th and 11th cranial nerves. These, along with paralysis of the 12th cranial nerve (Villaret's syndrome), occur with a retropharyngeal lesion of the posterior cranial fossa. Patients