THE SKULL. 61 



pletely filled by the ethmoid and the conchae nasales, superior 

 and inferior. It is bounded caudally by the lamina cribrosa of 

 the ethmoid (Fig. 42, o). The nasal cavity communicates with 

 the cranial cavity by the foramina for the olfactory fibres in the 

 lamina cribrosa ; with the nasopharynx by the choanae ; with the 

 exterior of the body by the nares; with the mouth-cavity by 

 the foramina incisiva or anterior palatine foramina (Fig. 42, s); 

 with the orbit by the sphenopalatine foramen and the naso- 

 lachrymal canal. It communicates directly also with the 

 frontal sinuses (Fig. 43, m, ;//), the sphenoidal sinuses (Fig. 

 43, /), and with the cells of the labyrinths of the ethmoid. 



JOINTS AND LIGAMENTS OF THE SKULL. 



Sutures of the Skull. The bones of the skull join each 

 other by means of immovable articulations known as sutures. 

 These sutures are designated by combining the names of the 

 bones between which they are situated : as, sphenofrontal suture 

 (sutura sphenof rontalis) , between the sphenoid and frontal; 

 nasomaxillary suture (sutura nasomaxillaris), between the 

 nasal and maxillary bones. When a suture joins the two 

 corresponding bones of opposite sides the prefix inter is used, 

 as the intermaxillary suture (sutura intermaxillaris) between 

 the maxillaries. The sutures bounding the parietals have, 

 however, received special names not derived in this manner. 

 The suture caudad of the parietals, separating them from the 

 occipital and interparietal, is known as the lambdoidal suture; 

 that between the two parietals is the sagittal suture; that 

 separating the parietals and squamous portions of the temporals 

 is the squamous sulure ; that between the parietals and frontals 

 is the coronal suture. The suture separating the two frontals 

 also is known as the frontal suture, in place of interfrontal. 



Articulations of the Mandible. In man the two halves of 

 the mandible are united craniad, so as to form a single bone. 

 In the cat the two halves are separate, but articulate closely at 

 the symphysis menti by a thin interarticular cartilage. 



The articulation of the mandible at the mandibular fossa of 

 the temporal is covered with a close articular capsule. The 



