40 • • OSTEOLOGY. 



complexus major muscle, and below it at the back is the occipital 

 tuberosity, on each side of which there is a roughened depression 

 for the attachment of the cordiform part of the ligamentum nuchas. 

 The occipital or ^mastoid ridge, continuous with the squamosal 

 bone, descends from the crest on each side, and gives attachment 

 to various muscles. The inferior or suboccipital portion presents, 

 a little below the tuberosity, a large, oval hole, the foramen 

 'magnum, through which pass the spinal cord, the spinal acces- 

 sory nerves, and the basilar artery ; the sides of this foramen, 

 the transverse diameter of which is the larger, are slightly 

 roughened for the attachment of the long odontoid ligaments, and 

 on each side is a large rounded prominence, the condyle, which 

 articulates with the atlas. A large process, the basilar process 

 (basi- occipital bone), passes forwards from the lower part of the 

 condyles, and forms the floor of the foramen magnum, being 

 flattened and slightly hollowed above, but rounded below, where 

 it gives attachment to the rectus capitis auticus major and minor 

 muscles ; it articulates Avith the sphenoid bone in front, and has 

 a fissure, the basilar fissure, running along its under surface, 

 terminating posteriorly in the foramen magnum. Two flattened 

 styloid processes extend downwards from the sides of the bone, 

 and give attachment to the obliquus capitis a.nt;icvis, stylo- 

 maxillaris, and styjo-hyoideus muscles ; and between each of these 

 processes and the condyle is a deep notch, the condyloid or stylo- 

 condyloid notch, at the bottom of which and just in front of the 

 condyle, is the condyloid foramen which gives passage to the 

 twelfth nerve. 



The interned or cerebral surface has, in the supraoccipital 

 portion, a vaulted concavity termed the occipital cufjola, which 

 covers the cerebellum ; while the superior surface of the basilar 

 process presents a pit, the basilar fossa, in the anterior part of 

 Avhich the pons va\;olii lies, and in the posterior part the me^ijUa 

 oblongata. The small foramina which enter the basilar process 

 from within the foramen magnum are for the passage of nutrient 

 blood-vessels. The superior border is serrated, and articulates 

 with the parietal and the lateral borders Avith the petrosal bones. 



The occipital bone resembles a vertebra more than any other 

 of the so-called cranial vertebrae ; in the young state it separates 

 into an inferior or basi-occipital part, representing the centrum ; 

 two lateral exoccipitals, representing the pedicles, laminae, &c. ; 

 and above, the supraoccipital portion, corresponding to the 



