34 



OF THE HEAD IN GENERAL. 



these there are two smaller fontanels on either side ; one is in the 

 angle of the temporal, parietal, and occipital bones, and the other is 

 at the junction of the temporal, parietal, and sphenoid bones. 



Ossa Wo?'?7iiana or Triquetra, are small, irregular in shape and 

 number, sometimes found in the sutures, particularly about the 

 middle of the lambdoidal. They have a distinct point of ossification. 



The dij^loe is the cellular bony structure between the external 

 and internal or vitreous tables ; it is traversed by channels lined 

 by a venous lining which empty into the emissaries of Santorini. 

 The cavity of the cranium is about six and a half inches in 

 length, five in breadth and five in height. When the calvaria 

 or arch of the cranium is removed, three deep fossa3 are ob- 

 served at the base on each side. The anterior is formed by the 

 frontal, sphenoid and ethmoid bones, and contains the anterior lobes 

 of the brain ; the middle, formed by the sphenoid and temporal bones, 

 lodges the middle lobe ; the posterior, formed by the occipital and 

 temporal bones, is for the cerebellum. 



Orbital cavity. — Is formed on each side by seven bones repre- 

 sented in this manner : 



Frontal 

 Sphenoid (lesser wing). 



Malar. 

 Sphenoid (greater wing). 



Lachrymal. 



Ethmoid (os planum). 



Sphenoid (body). 



Malar. 



Superior maxillary. 



Palate. 



The cavity is conical, the apex being formed by the optic foramen, 

 the base looks outwards and is somewhat quadrangular. The sphe- 

 noidal foramen or fissure opens into the orbit, and is also called /b/'a- 

 nien lacerum superiiis ; a slit or fissure between the sphenoid and 

 maxillary bones being the foramen, lacerum inferius. Besides these 

 there are other openings into the orbit already mentioned in the de- 

 scription of each bone. 



Nasal Cavity. — This is an irregular cavity, separated from its 

 fellow by the nasal septum, it has three distinct passages or rnen- 

 tuses. The superior is between the superior and middle turbinated 

 bones, and has opening into it the posterior ethmoidal cells, the sphe- 

 noidal cells, and the spheno-palatine foramen : the middle is between 

 the middle and inferior turbinated bones, and has opening into it the 

 frontal sinus, anterior ethmoidal cells, and the antrum, usually. The 

 inferior is the largest, and between the inferior turbinated bone and 

 the floor of the cavity. Into it opens the nasal duct. The opening 

 into the nasal cavity in front is called the anterior nares ; the open- 

 ing behind posterior nares or clivance. 



