36 STUDIES IN COMPARATIVE ANATOMY. 



of the mandible. The muscle is very thick where it passes 

 beneath the zygoma ; above this level are numerous tendinous 

 septa. The anterior fibres are united to a powerful tendon of 

 insertion, while the posterior fibres are muscular throughout. 



C. and L.— 274-5 (b) (temporal fascia); 276-7 (&); 287-8 (h). 



Masseter. — The principal portion of this muscle arises from 

 the lower border of the zygoma, extending from below the eye 

 to the insertion of sterno-maxillaris. The fibres pass down- 

 wards and backwards, to be inserted into the lower two-thirds 

 of the ascending ramus of the mandible as far as the angle. 

 Some of the deeper fibres arise from the posterior third of 

 the internal surface of the zygoma, pass forwards, and are 

 inserted into the mandible immediately below the sigmoid 

 notch. 



C. and L.-274-5 0') ; 276-7 {j,P). 



Pterygoideus externus arises from the upper part of the external 

 surface of the pterygoid bone. Inserted into the neck of the 

 mandible and into the inter-articular fibro-cartilage. 



C. and L.— 287-8 {p). 



Pterygoideus internum arises from the outer surface of the 

 pterygoid bone, below and slightly behind pterygoideus externus. 

 Inserted into the internal surface of the mandible below the 

 dental foramen. 



C. and L.— 287-8 {p^); 290-1 (not lettered). 



Mayer speaks of the internal pterygoid as " narrow and 

 short," while the external pterygoid is "thick and broad." The 

 relative strength was exactly reversed in our specimen. Super- 

 ficial to temporalis are the temporal fascia, a venous plexus, the 

 temporal artery, and the temporal gland. Beneath the muscle 

 is an important venous plexus. The masseter is crossed immedi- 

 ately below the zygoma by a small artery, a vein (which joins 

 the facial vein), the trunk of the facial nerve, and the parotid 

 duct. 



Buccinator. — Our notes of this muscle are incomplete. Dr 

 Watson's description, which we have verified in its principal 

 features, is as follows : — " Buccinator muscle arises from the 

 alveolar margins of both jaws, as well as from a powerful elastic 

 ligament which extends from the styloid process down to the 

 lower jaw. The fibres pass forward, and blend with the other 



