142 



SPECIAL ANA TOMY OF THE SKELETON 



cranii, in front of the notochord (Fig. 108). The parachordal cartilages (Fig. 109) unite to fc 

 a cartilaginous plate, from which the cartilaginous part of the occipital bone and the b; 

 sphenoid are developed. On the lateral aspect of the parachordal cartilages the otic or audit 

 vesicles are situated, and the mesoderm enclosing them is soon converted into cartilage, form 



Situation of olfactory pit Ethmoid plate 



and nasal Olfactory organ 

 septum^ 



\ 



Pituitary fossa 



TrabecuJa 

 cranii ' 



Situation of 



otic vesicle * 

 Parachordal -- 

 cartilage 



Notochord. 



Extension aroitnc 

 olfactory orgar, 

 Foramina for 

 olfactory nerves 



-Eyeball 

 - - Pituitary fosse 



Basicranial 

 "" cartilage 

 --Otic vesicle 



Notochord 



FIG. 108. Diagrams of the cartilaginous cranium. (Wiedersheim.) 



Crista galli. 



plate - 



Lesser wing of 

 sphenoid. 



Meckel's cartilage. 

 Malleus 

 Incus. 



Int. aud. meat 

 Jugular foramen 



Fossa subarcuata: 



For. hypogioss 



ptic foramen. 



Greater wing of 

 sphenoid. 



'Sella turcica. 

 Dorsum sellae. 



Can. nervi 

 facialis. 



Ear capsule. 

 Ductus endol. 



Foramen magnum. 



FIG. 109. Model of the chondrocraniurh of a human embryo, 8 cm. The membrane bones are not 

 represented. (From Hertwig's Handbuch der Entwickelungslehre.) 



the cartilaginous ear capsules. These cartilaginous ear capsules, which are of an oval sha 

 fuse with the lateral aspects of the basilar plate, and from them arise the petromastoid porti 

 of the temporal bones. The trabeculac cranii (Fig. 108) are two curved bars of cartilage wb 

 embrace the pituitary body; their posterior ends soon unite with the basilar plate, while tl 



