52 



THE SKELETON 



The inferior sjurfaee forms the upper lioumlary of the i<i)heno-palatine foramen, 

 and enters into tlie formation of the posterit)r \yAYi of tlie roof of the nasal fossa. 

 The superior surface lies flattened against the under surface of the pre-sphenoid. 

 The base of the cone is in contact with the posterior surface of the lateral mass of 

 the ethmoid. 



The deposits of earthy matter from which the si)henoidal turV)inals are formed 

 are laid down at the fifth month. 



At birth these bones are visible as small triantrular ossifications in the peri- 

 chondrium of the ethmo-vomerine plate near its junction with the pre-sphenoid, 

 and encloses a small recess which becomes a sphenoidal sinus. By the third year 

 the recesses have become completely enclosed and the bones have become hollow 



Ficj. 63.— The Sphenoidal Tcrbinals from an Old Skull. 



SPHENOIDAL TURBINAL 



ROSTRUM OF SPHENOID 



cones, the circular orifice representing the base eventually becoming the orifice of 

 the sphenoidal sinus. As the cavity enlarges, the median Avail atrophies so that 

 the inner Avail of the sinus is formed by the pre-sphenoid. As the turbinal en- 

 larges it ankyloses Avith adjacent bones. In many skulls it joins the lateral mass 

 of the ethmoid; more frequently it fuses with the pre-sphenoid; less frequently 

 Avith the palate. After the twelfth year they can rarely be separated from the skull 

 Avithout damage. In many disarticulated skulls they are so broken up that a por- 

 tion is found on the sphenoid, fragments on the palate bones, and the remainder 

 attached to the ethmoid. 



Sometimes, even in very old skulls, they are represented by a triangular plate 

 of extreme tenuity on each side of the rostrum of the sphenoid (fig. 63). 



Fig. 64. — The Inferior Turbinal, Adult Sphenoidal Turbinal and Lachrymal Bones. 



THE CREST OF LACHRYMAL 

 Tensor tarsi 



THE ORBITAL SURFACE 

 LACHRYMAL GROOVE 



HAMULAR PROCESS 



TURBINAL PROCESS 



THE LACHRYMAL PROCESS 



THE ETHMOIDAL PROCESS 



THE MAXILLARY PROCESS 



THE SPHENOIDAL TURBINAL WITH 

 AN ORBITAL PROCESS 



MIDDLE TURBINAL 



THE INFERIOR TURBINAL 



These are a pair of delicate, scroll-like bones, and may be regarded as dis- 

 memberments of the lateral masses of the ethmoid, Avith which they are closely 

 related. Each bone presents two surfaces, tAvo borders, and two extremities. 



