MUSCLES OF THE TRUNK. 



291 



internus in Ruminants is nearer the middle line than in the Horse. Its obliquity is also 

 greater, and the movements of diduction it gives the lower jaw are more extensive. In all the 

 animals, other than Solipeds, the stylo-maxillaris fasciculus of the digastricus is entirely absent, 

 and the muscle has only a single belly extending directly from the occipital to the maxillary 

 bone. In the Ox is found a siball square muscle, formed of transverse fibres, which unites the 

 two digastric muscles by passing beneath the base of the tongue. This muscle, in contracting, 

 may raise the hyoideal apparatus, and in this way supplement the tendon of the digastricua 

 and the inferior ring of the stylo-hyoideus. 



4. Hyoideal Region. 



The two flesliy planes composing the mylo-hyoideus are more distinct in Ruminants than 

 in the Horse. The stylo-hyoideus of these animals commences by a long thin tendon. The 

 muscle has no ring for the passage of the digastricus. 

 a feature observed 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 lerato-hyoideus is remarkable for 

 its relatively considerable volume; the occipito- 

 styloideus and the hyoideus transversus are absent. 



COMPAEISON OF THE MOSCLES OF THE HuMAN HeAD 

 ■WITH THOSE OF THE DOMESTICATED AnIMALS. 



In Man, there are described as muscles of the 

 head, the epicranial muscles, muscles of the face, and 

 those of the lower jaw. The hyoid and digastric 

 muscles are reckoned in the region of the neck. Here 

 tliey will be placed in the region of the head. 



1. Epicranial Muscles. 

 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 circumference 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 occipital 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 (ir the ex- 

 ternal ear, and are designated auricular muscles. 

 These epicranial muscles move the scalp forwards, 

 backwards, and sideways. 



2. 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. 170). 



1. The orbicularis oris, 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 (naso lahialis). 



2. The buccinator, corresponding to the buccinator 

 of animals. Besides its oflSce 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 Up. It resembles the 

 levator labii superioris, descends from the orbital margin of the supermaxilla, 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, the analogue of which is 

 found in the dilator naris lateralis. 



muscles of the human head 

 (superficial layer). 

 , Frontal portion of the occipito-fron- 

 talis ; 2, its occipital portion ; 3, its 

 aponeurosis ; 4, orbicularis palpebra- 

 rum ; 5, pyramidalis nasi ; 6, com- 

 pressor nasi; 7, orbicularis oris; 8, 

 levator labii superioris alasque nasi ; 



9, levator labii superioris proprius ; 



10, zygomaticus minor; 11, zygo- 

 maticus major ; 12, depressor labii 

 inferioris ; 13, depressor anguli oris ; 

 14, levator labii inferioris ; 15, super- 

 ficial portion of masseter ; 16, its deep 

 portion ; 17, attrahens aurem ; 18, 

 buccinator; 19, attollens aurem; 20, 

 temporal fascia covering temporal 

 muscle ; 21, retrahens aurem ; 22, 

 anterior belly of the digastricus, with 

 tendon passing through pulley ; 23, 

 stylo-hyoid muscle ; 24, mylo-hyoi- 

 deus ; 25, upper part of sterno-mas- 

 toid ; 26, upper part of trapezius — 

 the muscle between 25 and 26 is the 

 splenius. 



