56 TOPOGRAPHICAL ANATOMY OF THE 



The mucous membrane of the cheek should be reflected in order 

 that the ventral buccal glands may be examined. 



Dissection. — Remove the pterygoid muscles completely and clean up 

 the underlying structures. Turn the mylo-hyoid and mylo-glossal muscles 

 downwards a.^ far as possible, and observe that the fibres of these two 

 muscles cross each other obliquely. 



M. STYLOHYOIDEUS. — The elongated, rounded stylo-hyoid muscle 

 arises from the lateral aspect of the angle of the stylo-liyoid bone. The 

 fleshy belly of the muscle tapers to a narrow tendon, which splits to 

 permit the passage of the intermediate tendon of the digastricus, and is 

 inserted into the lateral face of the thyroid process of the hyoid bone. 



M. JUGULOHYOIDEUS. — The jugulo-hyoid muscle is sometimes 

 described as a part of the stylo-hyoid, of which it may be regarded as 

 the backward continuation. The muscle fills the narrow gap between 

 the jugular process of the occipital bone and the angular projection of 

 the stylo-hyal bone, and is attached to these bony parts. Some of its 

 fibres blend with those of the posterior belly of the digastric muscle. 



M. DIGA.^TRICUS. — The digastric and jugulo-mandibular muscles are 

 inextricably blended at their common origin from the jugular process 

 of the occipital bone. As its name indicates, the digastric possesses two 

 fleshy bellies — posterior and anterior — between which there is an 

 intermediate tendon that plays through the pulley formed by the 

 splitting of the tendon of insertion of the stylo-hyoid muscle. Between 

 the two tendons there is a small synovial bursa. 



The anterior belly of the digastric, and its insertion into the medial 

 aspect of the lower border of the molar part of the mandible, have 

 already received attention (page 13). 



It is of some morphological importance to note that the digastric 

 muscle receives nerve fibres from two distinct sources — the posterior 

 belly from the seventh cerebral nerve, and the anterior belly from the 

 fifth. 



The .salivary glands. — Although a large number of glands are 

 concerned in the production of the saliva, the expression " salivary 

 glands " is usually taken as indicating the three largest of these on 

 each side of the head — the parotid, the submaxillary, and the sub- 

 lingual. An examination of the parotid gland was made earlier 

 (page 42) ; the submaxillary and sublingual glands are now fully 

 revealed. 



The Sublingual Gland (Glandula sublingualis). — On turning down 

 the mylo-hyoid and mylo-glossal muscles, the pale-red, elongated and 

 lobulated sublingual gland was exposed to view. 



