THE HEAD. 79 



means of a cartilaginous substance that joins them together ; they are of very 

 unequal dimensions. The first, which is in relation with the body, is of medium 

 size, and is named the styloid cormi, small conm, or small branch. The second, 

 termed the styloid nucleus, is the smallest. The third, the largest, constitutes 

 the styloid process or bo7ie, or great branch. 



1. The styloid cornua {cfpohyaV) is a small cylindrical piece bearing a concave 

 diarthrodial surface on its inferior extremity to unite it to the body ; it is very 

 spongy, and is developed from two ossifying centres, one of which, the epiphysary, 

 is for the inferior extremity. 



2. The styloid nucleus {ceratohyal), which is often absent, is embedded in the 

 uniting cartilaginous substance. 



3. The styloid bone, or great hyoideal branch {stylohyal), is long, thin, flattened 

 on both sides, and directed obliquely from above to below, and before to behind ; 

 it presents two faces, two borders, and two extremities. The faces — an external 

 and internal — are marked by some few imprints. The anterior border is sharp 

 and slightly concave in its upper third. The posterior border is thicker, and is 

 divided into two portions — a superior or horizontal, which is very short, and an 

 inferior or vertical, much more extensive. The angle they form at their point 

 of junction presents a salient, and more or less roughened, tuberosity. The 

 superior extremity is united to the hyoideal prolongation of the temporal bone 

 by means of a cylindrical fibro-cartilage. By its inferior extremity, the styloid 

 bone is united either to the styloid nucleus or the styloid cornu, forming a sharp 

 elbow directed forwards. The styloid bone, developed from a single centre of 

 ossification, is almost entirely formed of compact tissue. 



Differential Characters of the Htoid Bone in other Animals. 



A. Ox, Sheep, Goat. — The hyoid bone of Ruminants is always composed of seven piecea. 

 the styloid nucleus, the presence of which is not constant in Solipeds, is never absent in these,' 

 and has the proportions of the second small branch. The anterior appendix is very short, and 

 only represents a large mamelon. 



B. Camel. — The liyoid is in this animal as in the Ox. 



C. Pig.— The body is voluminous and deprived of an appendix; the small branches are 

 short and consolidated with the body ; while the large branches, curved like an S, are very 

 thin, and are not united to the small branches and the temporal bone by libro-cartilage, but by 

 veritable yellow elastic ligaments. 



D. Carnivora. — The three pieces composing the body of the hyoid in early life are never 

 consolidated in the adult animal, but always remain isolated, as in Man. The middle piece 

 has no anterior appendix; the fibro-cartilages uniting the styloid portions to each other and to 

 the temporal bone are very long and flexible. 



12. WoEMiAN Bones (Fig. 48). 



This name has been given to small irregular bones which Worms observed 

 between some of the sutures of the cranial bones. They are developed after 

 birth, in the cranial, cranio-facial, and facial sutures. Their number and position 

 varies with the species of animals, and even the breeds of the same species. 



Vaguely described by Rigot, they have been recently studied by Cornevin, 

 who observes that the cranial Wormian bones are rare. In more than sixty 

 crania, they were found only once or twice in the Ox and Horse at the junction 

 of the petrous with the occipital bone. The Wormian bones of the cranio-facial 

 and the facial suture are more frequent ; nevertheless, they have been met with 

 almost exclusively in the heads of common-bred animals, particularly in the 

 bovine species. Cornevin has described a fontanelle lachrymo-nasal bone (Fig. 



