34 THE SKELETOX 



Crtror/c'ow7//(o/V/.— From tin- anterior to the iiiidille clinoid process. The ossifi- 

 cation of this ligament gives rise to a ring of l)one through which the internal 

 carotid arterv passes. 



Pterygo-spiiious. — This is attached to the spine of the sphenoid and the external 

 ptervgoicl plate near the upper third. 



Several other insigniticant bands have received names, but they are of no im- 

 portance. 



Blood-supply. — Tlie sjthenoid is supplied l)y branches of the middle and small 

 meningeal arteries; also the anterior deep ti'inporal and other branches of the in- 



FiG. 41.— The Sphenoid at Bikth. 



VIDIAN CANAL LINGULA 



temal maxillary, such as the Vidian, pterygo-palatine and spheno-palatine. The 

 bodv of the l^one also receives t"v\dgs from the internal carotid. 



Ossification. — The sphenoid is ossified in cartilage from twelve ossific nuclei 

 which appear in pairs. The nuclei are di\dsible into two sets, — those for the pre- 

 sphenoid, and those for the post-sphenoid. 



The post-sphenoid centres consist of four pairs disposed as follows: — One for 

 each ali-sphenoid (great wing). A pair of median nuclei for the basi-sphenoid, 

 and a nucleus for each lingula (sphenotic nucleus), and one for each internal 

 pterygoid. The external i)terygoid is an outgrowth from the great wing. 



The pre-sphenoid centres consist of a nucleus for each orbito-sphenoid (lesser 

 wings), and a median pair for the body of the pre-sphenoid. These nuclei ap})ear 



Fig. 4-2. — The Jugum Sphkxoiuale. 



at intervals from the eiglith week to the end of the third month in the following 

 order: ali-sphenoid, basi-sphenoid, linguhe, internal pterygoids, oritito-sphenoid, 

 and pre-sphenoid. The various earthy si)ots fuse together, so as to form at birtii 

 three pieces. Tlic median piece consists of the basi-si)henoid and Hngulfe, con- 

 joined with the prt'-sphenoid carrying the orljito-sphenoids; the two lateral pieces 

 are the ali-sphenoids (greater wings) carrying the internal pterygoid plates. Tlie 

 greater wings are joined to the lingula? by cartilage. The dorsum ephij)pii is car- 

 tilaginous at birth. In tlie course of the first year the orbito-si)henoids fuse in the 

 middle line to form the jugum sphenoidale, which excludes the anterior part of 

 the pre-sphenoid from the cranial cavity. The greater wings fuse with the lingula? 

 in the course of the first year. 



