86 



SPECIAL ANATOMY OF THE SKELETON 



artery and vein. In the interval between these two openings, but above them, 

 is an angular depression (fossa subarcuata), which lodges a process of the dura, 

 and transmits a small vein into the cancellous tissue of the bone. In the child 

 this depression is represented by a large fossa, the floccular fossa, which extends 

 backward as a blind tunnel under the superior semicircular canal. 



The inferior or basilar surface (Fig. 52) is rough and irregular, and forms part 

 of the base of the skull. Passing from the apex to the base, this surface presents 

 nine points for examination: (1) A rough surface, quadrilateral in form, which 

 serves partly for the attachment of the Levator palati and Tensor tympani muscles. 

 (2) The large, circular aperture of the carotid canal, the external carotid foramen 

 (foramen caroticum externum); the canal ascends at first vertically, and then, 

 making a bend, runs horizontally forward and inward; it transmits the internal 



Canals for Eustachian tube and 



TENSOR TYMPANI MUSCLE. 



Hough quadrilateral surface. _ 

 External opening q, 



carotid canal. 

 Canal for Jacobson's nerve. 



Aquaeductus cochleae. 



Canal for Arnold's nerve. 



Jugular fossa. 



Vaginal process. 



Styloid process. 

 Stylomastoid foramen. 

 Jugular surface. 

 Auricular fissure, 



8TYLOPHARYNGEUS 



FIG. 52. Petrous portion of the left temporal bone. Inferior surface. 



carotid artery and the carotid sympathetic plexus. Within the carotid canal 

 are several openings (canaliculi caroticotympanici), which transmit tympanic 

 branches of the internal carotid artery and of the carotid sympathetic plexus. 

 (3) The opening of the aquaeductus cochleae (apertura externa canaliculi cochleae), 

 a small, triangular opening, lying on the inner side of the latter, close to the pos- 

 terior border of the petrous portion; it transmits a vein from the cochlea, which 

 joins the internal jugular. (4) Behind these openings a deep depression, the 

 jugular fossa (fossa jugularis), which varies in depth and size in different skulls; 

 it lodges the lateral sinus, and, with a similar depression on the margin of the 

 jugular process of the occipital bone, forms the foramen lacerum posterius or 

 jugular foramen. (5) A foramen which is the opening of a small canal (canalicu~ 

 lus tympanicus) for the passage of Jacobson's nerve (the tympanic branch of the 

 glossopharyngeal); this foramen is seen in front of the bony ridge dividing the 



