THE OCCIPITAL BONE 35 



magnum, one connecting the two lateral angles. Where these 

 intersect is the internal occipital protuberance, not always 

 opposite the external. The ridges mark off four hollows, 

 the superior and inferior occipital fossce, which lodge the pos- 

 terior cerebral and the cerebellar lobes. The ridges are grooved 

 for venous sinuses. The space where the longitudinal sinus 

 is continued into a lateral one, generally the right, lodges the 

 torcular Herophili (wine-press of Herophilus). Below this the 

 vertical ridge is sharp, and named the internal occipital crest. 



The condylar portions bear the articular surfaces for the 

 atlas; these condyles converge toward the front, are doubly 

 convex, and somewhat everted. At the inner side of each 

 is a rough impression for a lateral odontoid ligament. Per- 

 forating the condyle from within out is the anterior condylar 

 foramen for the hypoglossal nerve and a branch of the ascending 

 pharyngeal artery. Immediately above this foramen is a 

 heaping up of bone designated as the eminentia innominata. 

 Behind the condyle is a posterior condylar fossa; it may be 

 perforated by a foramen for the passage of a vein from the 

 lateral sinus; both fossa and foramen are inconstant. External 

 to the condyle is the jugular process, analogue of a transverse 

 process; it lies above the transverse process of the atlas, and 

 it presents in front the jugular notch, which helps form the 

 jugular foramen; the right notch is usually the larger. The 

 extremity of the process presents an irregular facet for union 

 with the temporal bone; this union is osseous at the twenty- 

 fifth year. The upper surface presents the end of the lateral 

 sulcus (for the lateral sinus) leading to the jugular notch; 

 here the posterior condylar foramen opens if present. On 

 the under surface is attached the rectus capitis lateralis muscle. 



The basilar process projects forward and upward in the 

 middle of the base of the skull and at the top of the pharynx, 

 increasing in thickness and diminishing in width. Superiorly 

 is a basilar groove for the medulla, and at either lateral margin 

 a shallow sulcus for the inferior petrosal sinus. Inferiorly 

 in the middle line is the pharyngeal tubercle for aponeurotic 

 attachment of the superior constrictor of the pharynx; on 

 each side of it are attached the rectus capitis anticus major 

 and minor muscles. 



The superior border extends on each side from the superior 

 to the lateral angle, is deeply serrated for articulation with 



