312 



THE MUSCLES AND FASCIA. 



nerve, arid in front of it the buccal vessels and nerve. Its anterior border is 

 separated from the malar bone by a mass of fat. 



Nerves. Both muscles are supplied by the inferior maxillary nerve. 



10. Pterygo-mandibular Region (Fig. 200). 

 External Pterygoid. Internal Pterygoid. 



Dissection. The Temporal muscle having been examined, saw through the base of the 

 coronoid process, and draw it upward, together with the Temporal muscle, which should be 

 detached from the surface of the temporal fossa. Divide the ramus of the jaw just below the 

 condyle, and also, by a transverse incision extending across the middle, just above the dental 

 foramen ; remove the fragment, and the Pterygoid muscles will be exposed. 



The External Pterygoid is a short, thick muscle, somewhat conical in form, 

 which extends almost horizontally between the zy gomatic fossa and the condyle of 

 the jaw. It arises by two heads, separated by a slight interval : the upper arises 

 from the inferior surface of the greater wing of the sphenoid and from the ptery- 

 goid ridge, which separates the zygomatic from the temporal fossa ; the lower 

 from the outer surface of the external pterygoid plate. Its fibres pass horizon- 

 tally backward and outward, to be inserted into a depression in front of the neck 

 of the condyle of the lower jaw and into the corresponding part of the inter- 

 articular fibro-cartilage. 



Relations. By its external surface, with the ramus of the lower jaw, the 

 internal maxillary artery, which crosses it, 1 the tendon of the Temporal muscle, 

 and the Masseter ; by its internal surface it rests against the upper part of the 

 Internal pterygoid, the internal lateral ligament, the middle meningeal artery, 



FIG. 200. The Pterygoid muscles, the zygomatic arch and a portion of the ramus of the jaw having been 

 removed. 



and inferior maxillary nerve ; by its upper border it is in relation with the temporal 

 and masseteric branches of the inferior maxillary nerve ; by its lower border it is 

 in relation with the inferior dental and gustatory nerves. Through the interval 

 between the two portions of the muscle, the buccal nerve emerges and the internal 

 maxillary artery passes, when the trunk of this vessel lies on the muscle (see 

 Fig. 200). 



The Internal Pterygoid is a thick, quadrilateral muscle, and resembles the 

 Masseter in form. It arises from the pterygoid fossa, being attached to the inner 

 1 This is the usual relation, but in many cases the artery will be found below the muscle. 



