184 



OSTEOLOGY 



petrotympanic fissure. The anterior and larger part of the fossa articulates with 

 the condyle of the mandible and is limited behind by the external acoustic meatus : 

 the posterior part sometimes lodges a portion of the parotid gland. The styloid 

 process extends downward and forward for a variable distance from the lower 

 part of the tympanic part, and gives attachment to the Styloglossus, Stylohv- 

 oideus, and Stylopharyngeus, and to the stylohyoid and stylomandibular ligaments. 

 Projecting downward behind the external acoustic meatus is the mastoid process, 

 to the outer surface of which the Sternocleidomastoideus, Splenius capitis, and 

 Longissimus capitis are attached. 



The Infratemporal Fossa (fossa infratemporalis; zygomatic fossa) (Fig. 189). The 

 infratemporal fossa is an irregularly shaped cavity, situated below and medial to the 

 zygomatic arch. It is bounded, in front, by the infratemporal surface of the maxilla 



Inferior orbital fissure 



Infratemporal crest 



Pterygomaxillary fissm e 



Pterygoid liamuLus 



External acoustic meatus 

 Tympanic part of temporal 

 Styloid process 

 Mandibular cavity 

 Zygomatic process (cut) 

 Lateral pterygoid plate 



FIG. 189. Left infratemporal fossa. 



and the ridge which descends from its zygomatic process; behind, by the articular 

 tubercle of the temporal and the spina angularis of the sphenoid; above, by the great 

 wing of the sphenoid below the infratemporal crest, and by the under surface of 

 the temporal squama; below, by the alveolar border of the maxilla; medially, by 

 the lateral pterygoid plate. It contains the lower part of the Temporalis, the 

 Pterygoidei internus and externus, the internal maxillary vessels, and the man- 

 dibular and maxillary nerves. The foramen ovale and foramen spinosum open on 

 its roof, and the alveolar canals on its anterior wall. At its upper and medial 

 part are two fissures, which together form a T-shaped fissure, the horizontal limb 

 being named the inferior orbital, and the vertical one the pterygomaxillary. 



The inferior orbital fissure (fissura orbitalis inferior; sphenomaxillary fissure], 

 horizontal in direction, opens into the lateral and back part of the orbit. It is 

 bounded above by the lower border of the orbital surface of the great wing of the 



