230 ////-' Ml 9GEJQS 



ve. In nil tho animals, tin 1 lij1n-innx!U>iri* fii-irii-iiliiH of tin- (///ixfr<>* U 

 entirely absent, nml tlic muscle has only a single belly r\tenilini? directly i'rm the 

 occipital to the maxillary bone. In tho Ox is found a .small .-ipi n. mu-el.-, fcirm'-d "!' 

 tr.m>vcrse ti)>n s, which unites the two digastric nm^ele, 1,\ |>aiug beneath tin- !' 

 the tongue. This muscle, in contracting, may raise the l.\i,l,- ,| apparatus, an<l in this 

 way supplements the tendon of tho ili^i.-trii-iH ami tin- inferior ring of the 

 hyoideus. 



C. Hyoid Region. 



Tho two fleshy planes composing the mylo-hyoideus are more distinct in Ruminants 

 than in the Horse. The ttyloJiyoidau of the.se animals ecimmenee.s by a long thin 

 tendon. The muscle has no ring for the passage of the digastricus, a feature ob.s<i \ id 

 in all the domesticated animals except Solipeds. 



In the Carnivora, the stylo-hyoideus, formed by a narrow, very thin, and pale 

 fleshy band, commences on the mastoid portion of the temporal bone by a small tendon; 

 the kerato-hyoideus is remarkable for its relatively considerable volunv; ; the occljiilo- 

 slyloideus and the transversalis hyoideus are absent. 



COMPARISON OF THE MUSCLES OF THE HOMAN HEAD WITH THOSE OF THE DOMESTICATED 



ANIMALS. 



In Man, there are described as muscles of the head, the epicranial muscles, muscles of 

 the fare, and those of the lower jaw. The hyoul and digastric muscles are reckoned in 

 the region of the neck. Here they will be placed in the region of tho head. 



A. Epicranial Muscle*. 



The middle portion of the human cranium is covered by an aponeurosis that adheres 

 closely to the hairy scalp, but glides easily on the surface of the bones. To the circum- 

 ference of this epicranial aponeurosis are attached four muscles which move it. One 

 of them, attached behind to the superior occipital curved line, is named the occi/n'tnl 

 muscle ; another, fixed in front of the forehead, is called the frontal muscle; the other two, 

 double and lateral, are inserted on the face of the temporal bone or the external ear, 

 and are designated auricular muscles. These epicranial muscles move the scalp for- 

 wards, backwards, and sideways. 



B. Muscles of the Face. 



These are fourteen in number, ten of which are found in the domesticated animals. 

 We commence by describing these common muscles (fig. 113). 



1. The orbicular is of the lips, which has a fasciculus that passes to the skin from the 

 columna of the nose ; this fasciculus is termed the depressor of the columna, or 

 moustache muscle (iiaso labialis). 



2. The buccinator, corresponding to the alveolo-lubialis of animals. Besides its office 

 in mastication, it takes an important part in the blowing of wind instruments. 



3. The superficial elevator of the wing of the nose and the upper lip. It resembles the 

 supernaso-labialis, descends from the orbital margin of the supcrmaxilla, passes along 

 the wing of the nose, and is lost in the upper lip. 



4. The deep elevator of the wing of the nose and the upper lip, whose analogue is 

 found in the superrnaxillo-labialis of animals. 



5. The great zygomaticus, whose presence is constant in all species. 



6. The small zyyomaticu*, represented in the Horse by only the small oblique 

 fasciculus sometimes found beneath the great zygomntiens. 



The small zygoinaticus and the two elevators of the lips are lachrymal muscles ; by 

 their simultaneous contraction they express discontent and melancholy. The great 

 zygomaticus, on tho contrary, is the muscle of laughter ; it draws the commissures of 

 the lips outwards. 



7. The canine, or great supermaxillo-nasnl of animals, is attached beneath the infra- 

 orbital foramen, and terminates in the skin of the upper lip. 



8. The rinorius of Umitnrini. 



9. The muscle of the chin (mento-labialit). 



10. The myrtiformis, or middle anterior of BotHgdai 



The other facial muscles of Man, whose analogues it is difficult or impossible to find 

 in animals, are : 



