The measurements of the clivus, the foramina on the external base of the skull and the superior vertebrae

Anatomical measurements are made on the clivus and the upper cervical column. These values are important for transoral, transpalatinal approaches to the clivus and to atlas and axis. The mean-values of the length of clivus in adults were 45 mm on the internal cranial base, on the external the length between the basion and the vomer was estimated with 27.9 mm, the tuberculum pharyngeum is situated on our material 11.2 mm rostral of the basion. The anterior part of clivus in the external cranial base has a width of 22.5 mm, the posterior part has one of 42.8 mm. Included are measurements of the hypoglossal canal and measurements of foramen lacerum externum. The postnasal enlargement of the most portals of the cranial base is given in Fig. 5. The occipital condyles are 22.9 mm in length, the angle between the condyles was 51.4 degrees. The thickness of clivus was 18.3 mm in a level 28 mm rostral of basion and 9.3, 11 mm rostral of basion. Given are also the thickness of substantia corticalis of clivus and the area of posterior wall of sphenoid sinus. Measured are also the distances between dens axis and anterior arch of atlas and basion. The height of anterior arch was found larger than by other researchers. Included are length and width values of the upper cervical column and the insertion areas of the longus capitis and rectus capitis anterior muscles.