768 MR. ST. GEORGE MIVART ON THE [JuilC 27, 



covering the trapezius, constitute a more posterior layer of superfi- 

 cial fibres having no connexion with the mandible ; these may per- 

 haps represent \\\q platysma myoides (fig. 1, P. My.). 



On removing the mylo-hyoid a muscle becomes visible wliich is 

 of rather large size, and descends from the middle of the lower border 

 of the inner surface of the mandible to the cornu of the os hyoides. 

 This is the cerato-mandibular (fig. 2, C. M.). 



The depressor mandibulce, which may perhaps represent the di- 

 gastric (figs. 1, 2 & 2a, Z). M.), arises from the posterior margin of 

 the parietal process. Descending, it is inserted into the extreme pos- 

 terior end of the mandible. 



The temporal muscle is very thick and large, and fills the tem- 

 poral fossa. It arises from the outside of the parietal process and 

 from the front surface of the os quadratum*. It is inserted into the 

 coronoid process of the mandible, and into the upper border of the 

 bone behind that process. 



Internal pteryyokl. This large, thick muscle takes origin from the 

 inner side of the pterygoid, and is inserted into the inside and pos- 

 terior extremity of the mandible. 



The external pterygoid m&^% outside the pterygoid, and is inserted 

 into the inner surface of the mandible rather in front of the insertion 

 of the internal pterygoid and behind the coronoid process. 



Trapezius (figs. 1 & '?, Ts.). This muscle, as Meckel observesf, 

 is very extensive. It lies beneath the platysma myoides, but super- 

 ficial to the levator claviculse ; and the lowest part of its insertion 

 overlaps that of the omo-hyoid (fig. 2, Ts., O. //.). It forms a 

 very delicate muscular layer, especially above, but becomes thicker 

 towards its insertion. It arises, bj' aponeurosis, from the middle 

 line of the back, from the last cervical to the fifth dorsal vertebra, 

 and more anteriorly from the superficial fascia of the neck, and also 

 from the margin of the parietal process, towards which part it is 

 intimately united to the sterno-cleido-mastoid. The fibres converge, 

 and are inserted into about the upper half of the clavicle between 

 the deltoid and the insertions of the levator claviculse, omo-hyoid, 

 and sterno-cleido-mastoid. The most anterior and posterior fibres 

 antagonize each other. 



The rhomboid is wanting, unless it be represented by some part 

 of the muscle described as the serratus magnus. 



Latissimus dorsi (figs. 1 & 9, i. D.). This is a large muscle, and 

 arises from the spines of the dorsal vertebrae from the first to the 

 ninth, and from the last three cervical spines. Its fibres, converging, 

 end in a strong tendon, which is inserted into the outer side of the 

 summit of the humerus below, passing rather in front of, the in- 

 sertion of the infraspinatus, covered moreover by the third head of 

 the triceps. The tendon of the latissimus dorsi gives off another 

 small tendon from its inferior margin (fig. 9, t.), which joins the 

 triceps just where the two long heads of that muscle unite together. 



* The part arising from the os quadratum and columella is considered bv 

 Stiinnius to be the mco'scter. 

 t Loc. cit. p. 311. 



