1897.] NATURAL SCIENCES OF PHILADELPHIA. 41 



THE MUSCLES OF THE LOWER JAW. 



Unlike other forms of temporal muscle, the superficial and poste- 

 rior fascicle overlies to a slight extent only the anterior and deeper 

 part, but in the main arises separately from the skull. It can be raised 

 easily by the director just above the auditory meatus and separated 

 from the anterior fascicle by a little artificial dissection. 



The masseter muscle arises from the inferior orbital margin. The 

 anterior surface as it overlies the lower jaw reaches a line answering 

 to that of the third molar, almost as far as the anterior edge of the 

 line of origin of the muscle. But its insertion is strictly confined to 

 the angle of the jaw; thus a probe can be passed between the ante- 

 rior third of the muscle and the lower jaw. 



The digastric muscle is without tendinous intersection, and is in- 

 serted almost the entire length of the lower jaw. 



THE MUSCLE OF THE SUPERIOR EXTREMITY. 



The muscles which are attached to the occiput and cervical ver- 

 tebras on the one part and the shoulder girdle and the side of the 

 chest, humerus and bones of the forearm on the other, constitute a 

 natural system, though they are variously distributed in the gener- 

 ally accepted myologic scheme. 



I place in this system the following muscles, the grouping by 



brackets indicating the association through annectant fascicles : 



f Sterno-cleido-mastoideus. 

 ( Trapezius. 



j Splenius. 



( Scalenus anticus. 



f Transversalis colli. 

 -< Pectoralis major. 

 (^Serratus magnus. 



f Deltoideus. 



-< Pectoralis major. 



(_ Brachialis anticus. 



Rhomboideus. 



Levator anguli scapulas. 

 Latissimus dorsi. 



The Sterno-Cleido-Mastoideus is a sheet whose fold 11 lies at the 

 median border. The clavicular and sternal origins are continuous, 



11 For an opinion entertained respecting muscles which are composed on the 

 plan of a folded sheet, see a paper by the author on the Muscles of the Limbs 

 of the Kaccoon (Procyon lotor), Proceedings of the Academy of Natural Sci- 

 ences of Philadelphia, May, 1882. 

 4 



