20 = MR. E. J. SIDEBOTHAM ON THE [Jan. 20, 



part. These fibres chiefly converge to the anterior inferior angle of 

 the muscle and form a large fleshy mass, which is inserted into 

 anterior border and outer surface of coronoid process, whilst the 

 posterior few fibres are inserted into outer surface of coronoid. The 

 much larger deep part is separated from it by tendinous fibres. It 

 arises from the whole of the temporal fossa and posterior part of 

 inner surface of zygoma. It is inserted into inner surface and upper 

 border of coronoid. 



Internal pterygoid. — Arises from outer surface of pterygoid. 

 Its fibres passing outwards, backwards, and slightly downwards, are 

 inserted into border of incurved portion of lower jaw, its posterior 

 fibres meeting those of masseter as described above. 



Mvfernal pterygoid. — A small roundish muscle, arising from 

 pterygoid at upper and posterior part of internal pterygoid. Its fibres 

 pass downwards and backwards, and are inserted into base of condyle 

 of jaw. 



Sterno-hyoid. — Long, ribbon- shaped, arising from inner surface 

 of second piece of sternum ; inserted into front of hyoid. 



Ster no-thyroid. — Smaller than preceding and overlain by it. 

 Arises with sterno-hyoid, and is united with it for a short distance. 

 United above with its fellow, and inserted with it into front of 

 thyroid. 



Thyroid hyoid. — Passes from side of thyroid to great cornu of 

 hyoid. 



Omo-hyoid. — A long narrow band arising from vertebral border 

 of scapula. Inserted into hyoid, just external to sterno-hyoid. No 

 tendinous intersection could be seen. 



Mylo-hyoid. — Flat and thin, arising from posterior half of mylo- 

 hyoid ridge of lower jaw. Inserted into median raphe, and its 

 posterior fibres into tendinous expansion of posterior belly of digastric. 



Genio-hyoid. — Narrow origin by tendinous fibres from inner 

 border of lower jaw close to symphysis. It lies close to its fellow, 

 and is inserted into front of hyoid. It sends a small muscular 

 fasciculus to genio-hyoglossus. 



Hyoglossus. — A large muscle extending from side of hyoid 

 under cover of genio-hyoid. Its fibres pass forwards and inwards to 

 be inserted into side of tongue for its posterior two thirds. 



Genio-hyoylossus. — Arises from inner side of lower jaw close to 

 middle line. Its fibres arch back to be inserted into posterior half 

 of under surface of tongue and lower border of internal surface of 

 hyoid, to whicli it is connected by tendinous fibres. 



Diyustric. — Posterior belly arises by a rounded tendon from par- 

 occipital process. It forms a rounded belly which flattens out, 

 forming a tendinous expansion which meets its fellow in middle line. 

 Anterior belly arises from su[)erficial aspect of this expansion, and 

 forming a flat muscle, is inserted into lower border of lower jaw at 

 its middle. 



Paroccipito-hyoid. — A narrow band of fibres passing from parocci- 

 pital process, just internal to origin of posterior belly of digastric, to 

 great cornu of hyoid. 



