48 SPECIAL ANATOMY. 



1. Inferior surface, slightly ascending forwards, rough (for attachments of 

 muse. red. cap. ant. major et minor}, forms the bony roof of the pharynx; pre- 

 sents the spina basilaris sen pharyngea (for the m. constrict, pharyng. superior). 



2. Superior surface, ascends obliquely forwards and upwards; smooth; 

 forms fossa basilaris, for medulla oblongata ; at the sides, narrow grooves for the 

 sinus petrosi inferiora. 



3. Anterior surface, joins with the sphenoid bone ; the posterior sharp sur- 

 face forms the anterior boundary of the for. magn.; the lateral borders are in 

 contact with the petrous bone. 



Borders and Angles. The two superior borders form, with the posterior of 

 the Parietal bones, the Lambdoidal suture ; instead of the obtuse angles in 

 which they unite, in the new-born child we find the lesser fontanelle, foniiculus 

 triangularis ; in the place where the Occipital, Parietal, and Mastoid portion of 

 temporal meet together the posterior lateral Fontanelle, later the ossa Worm- 

 iana; generally about one inch lower, the for. mastoidcum (for emissar. San- 

 torini). 



Texture. The internal osseous table is very fragile, particu- 

 larly thin and translucent at the inferior part in the fossae cerebelli. 

 In the condyloid and basilar portions the spongy tissue predomi- 

 nates. 



Development. Four points of ossification; one for the shell, 

 which appears first; two for the articular, one for the basilar 

 portion. 



Foramen magnum occipitale, the great occipital foramen, 

 serves for the passage of the spinal cord with its membranes, the 

 vertebral and spinal arteries, and the accessory nerves of Willis. 



48. 2. Os Sphenoideum, sphenoid bone. 



Position : in the anterior and middle part of the base of the 

 skull. 



Figure: irregular, something like a flying bat; formed of a 

 central portion, body, with four horizontal large and small wings, 

 and two vertical processes directed downwards. 



Junction : with all the cranial bones, and with the following 

 bones of the face : Vomer, ossa zygomatica, palatina, and 

 maxillaria superiora. 



A. Body the most central, cuboid portion, containing two cavities separated 

 by a partition, sinus sphenoidales. which are closed in front by two triangular 

 bones, ossicula seu cornua Bertini, and only connected by one small opening 

 with the posterior Ethmoidal cells. The body presents 6 surfaces: 



A. Superior, cerebral surface, Sella turcica, s. equina, s. ephippium, Turkish 

 saddle. From before to behind: 



1. A slight depression for the Nerv. Olfactorii. 



2. A transverse groove leading to the foramina Optica, (for the Chiasma or 

 commissura Nerv. Optica.') 



3. A four-sided fossa, fossa pituit aria (for the Hypophysis cerebri), properly the 

 setta turcica, 



4. Process, clinoidei medii, on the anterior, posteriores, on the posterior border of 

 the saddle. 



